vr[ - … · installing a new part, clean off any dust or metal filings. (2) Tightening Sequence...

FJ151VFJ180V

(Year 2010 ∼ )

4-Stroke Air-Cooled Gasoline Engine

Service Manual

This quick reference guide will assistyou in locating a desired topic or pro-cedure.•Bend the pages back to match theblack tab of the desired chapter num-ber with the black tab on the edge ateach table of contents page.•Refer to the sectional table of contentsfor the exact pages to locate the spe-cific topic required.

Quick Reference Guide

General Information 1 jPeriodic Maintenance 2 jFuel System 3 jCooling System 4 jEngine Top End 5 jLubrication System 6 jCamshaft/Crankshaft 7 jStarter System 8 jElectrical System 9 jTroubleshooting 10 j

FJ151VFJ180V

(Year 2010 ∼ )

4-Stroke Air-Cooled Gasoline Engine

Service ManualAll rights reserved. No parts of this publication may be reproduced, stored in a retrieval system,

or transmitted in any form or by any means, electronic mechanical photocopying, recording orotherwise, without the prior written permission of Quality Assurance Department/Motorcycle & EngineCompany/Kawasaki Heavy Industries, Ltd., Japan.No liability can be accepted for any inaccuracies or omissions in this publication, although every possible

care has been taken to make it as complete and accurate as possible.The right is reserved to make changes at any time without prior notice and without incurring an obligation

to make such changes to products manufactured previously.All information contained in this publication is based on the latest product information available at the time

of publication. Illustrations and photographs in this publication are intended for reference use only and maynot depict actual model component parts.

© 2010 Kawasaki Heavy Industries, Ltd. First Edition (0) : Aug. 20, 2010

LIST OF ABBREVIATIONSA ampere(s) lb pound(s)ABDC after bottom dead center m meter(s)AC alternating current min minute(s)ATDC after top dead center N newton(s)BBDC before bottom dead center Pa pascal(s)BDC bottom dead center PS horsepowerBTDC before top dead center psi pound(s) per square inch°C degree(s) Celsius r revolutionDC direct current rpm revolution(s) per minuteF farad(s) TDC top dead center°F degree(s) Fahrenheit TIR total indicator readingft foot, feet V volt(s)g gram(s) W watt(s)h hour(s) Ω ohm(s)L liter(s)

EMISSION CONTROL INFORMATION

To protect the environment in which we all live, Kawasaki has incorporated crankcase emission(1) and exhaust emission (2) control systems (EM) in compliance with applicable regulations ofthe United States Environmental Protection Agency and California Air Resources Board.1. Crankcase Emission Control SystemA sealed-type crankcase emission control system is used to eliminate blow-by gases. The blow

-by gases are led to the breather chamber through the crankcase. Then, it is led to the air cleaner.Oil is separated from the gases while passing through the inside of the breather chamber from

the crankcase, and then returned back to the bottom of crankcase.2. Exhaust Emission Control SystemThe exhaust emission control system applied to this engine consists of a carburetor and an ig-

nition system having optimum ignition timing characteristics.The carburetor has been calibrated to provide lean air/fuel mixture characteristics and optimum

fuel economy with a suitable air cleaner and exhaust system.

TAMPERING WITH EMISSION CONTROL SYSTEM PROHIBITED

Federal law and California State law prohibits the following acts or the causing thereof: (1) theremoval or rendering inoperative by any person other than for purposes of maintenance, repair,or replacement, of any device or element of design incorporated into any new engine for thepurpose of emission control prior to its sale or delivery to the ultimate purchaser or while it is inuse, or (2) the use of the engine after such device or element of design has been removed orrendered inoperative by any person.

Among those acts presumed to constitute tampering are the acts listed below:Do not tamper with the original emission related part:

• Carburetor and internal parts• Spark plug•Magneto or electronic ignition system•Fuel filter element• Air cleaner elements•Crankcase•Cylinder head•Breather chamber and internal parts• Inlet pipe and tube

Foreword

This manual is designed primarily for use bytrained mechanics in a properly equipped shop.However, it contains enough detail and basic in-formation to make it useful to the owner who de-sires to perform his own basic maintenance andrepair work. A basic knowledge of mechanics,the proper use of tools, and workshop proce-dures must be understood in order to carry outmaintenance and repair satisfactorily. When-ever the owner has insufficient experience ordoubts as to his ability to do the work, all ad-justments, maintenance, and repair should becarried out only by qualified mechanics.In order to perform the work efficiently and

to avoid costly mistakes, read the text, thor-oughly familiarize yourself with the proceduresbefore starting work, and then do the work care-fully in a clean area. Whenever special tools orequipment are specified, do not use makeshifttools or equipment. Precision measurementscan only be made if the proper instruments areused, and the use of substitute tools may ad-versely affect safe operation.To get the longest life out of your engine:• Follow the Periodic Maintenance Chart in theService Manual.• Be alert for problems and non-scheduledmaintenance.•Use proper tools and genuine Kawasaki en-gine parts. Genuine parts provided as spareparts are listed in the Parts Catalog.• Follow the procedures in this manual care-fully. Don’t take shortcuts.•Remember to keep complete records of main-tenance and repair with dates and any newparts installed.

How to Use This ManualIn this manual, the product is divided into

its major systems and these systems make upthe manual’s chapters. The Quick ReferenceGuide shows you all of the product’s systemand assists in locating their chapters. Eachchapter in turn has its own comprehensive Ta-ble of Contents.For example, if you want ignition coil informa-

tion, use the Quick Reference Guide to locate

the Electrical System chapter. Then, use theTable of Contents on the first page of the chap-ter to find the Ignition coil section.Whenever you see these WARNING and

CAUTION symbols, heed their instructions!Always follow safe operating and maintenancepractices.

WARNINGThis warning symbol identifies specialinstructions or procedures which, if notcorrectly followed, could result in per-sonal injury, or loss of life.

CAUTIONThis caution symbol identifies specialinstructions or procedures which, if notstrictly observed, could result in dam-age to or destruction of equipment.

This manual contains four more symbols (inaddition toWARNING andCAUTION) which willhelp you distinguish different types of informa-tion.

NOTEThis note symbol indicates points of par-ticular interest for more efficient and con-venient operation.

• Indicates a procedural step or work to bedone.Indicates a procedural sub-step or how to dothe work of the procedural step it follows. Italso precedes the text of a WARNING, CAU-TION, or NOTE.Indicates a conditional step or what action totake based on the results of the test or inspec-tion in the procedural step or sub-step it fol-lows.

In most chapters an exploded view illustrationof the system components follows the Table ofContents. In these illustrations you will find theinstructions indicating which parts require spec-ified tightening torque, oil, grease or a lockingagent during assembly.

GENERAL INFORMATION 1-1

1

General InformationTable of Contents

Before Servicing ..................................................................................................................... 1-2Model Identification................................................................................................................. 1-4General Specifications............................................................................................................ 1-5Unit Conversion Table ............................................................................................................ 1-6

1-2 GENERAL INFORMATIONBefore Servicing

Before starting to service the engine, carefully read the applicable section to eliminate unnecessarywork. Photographs, diagrams, notes, cautions, warnings, and detailed descriptions have been in-cluded wherever necessary. Nevertheless, even a detailed account has limitations, a certain amountof basic knowledge is required for successful work.

Especially note the following:(1) Dirt

Before removal and disassembly, clean the engine. Any dirt entering the engine, carburetor, orother parts, will work as an abrasive and shorten the life of engine. For the same reason, beforeinstalling a new part, clean off any dust or metal filings.

(2) Tightening SequenceGenerally, when installing a part with several bolts, nuts, or screws, start them all in their holes

and tighten them to a snug fit. Then tighten them evenly, in a staggered sequence. This is toavoid distortion of the part and/or causing gas or oil leakage. Conversely when loosening thebolts, nuts, or screws, first loosen all of them by about a quarter of a turn and then remove them.Where there is a tightening sequence indication in this Service Manual, the bolts, nuts, or screwsmust be tightened in the order and method indicated.

(3) TorqueWhen torque values are given in this Service Manual, use them. Either too little or too much

torque may lead to serious damage. Use a good quality, reliable torque wrench.(4) Force

Common sense should dictate how much force is necessary in assembly and disassembly. Ifa part seems especially difficult to remove or install, stop and examine what may be causing theproblem. Whenever tapping is necessary, tap lightly using a wooden or plastic-faced mallet. Usean impact driver for screws (particularly for the removal of screws held by a locking agent) in orderto avoid damaging the heads.

(5) EdgesWatch for sharp edges, especially during major engine disassembly and assembly. Protect your

hands with gloves or a piece of thick cloth when lifting the engine or turning it over.(6) High-Flash Point Solvent

A high-flash point solvent is recommended to reduce fire danger. A commercial solvent com-monly available in North America is Standard solvent (generic name). Always follow manufacturerand container directions regarding the use of any solvent.

(7) Gasket, O-ringDo not reuse a gasket or O-ring once it has been in service. The mating surfaces around the

gasket should be free of foreign material and perfectly smooth to avoid oil or compression leaks.(8) Liquid Gasket, Non-Permanent Locking Agent

Follow manufacturer’s directions for cleaning and preparing surfaces where these compoundswill be used. Apply sparingly. Excessive amounts may block engine oil passages and causeserious damage. An example of a non-permanent locking agent commonly available in NorthAmerica is Loctite Lock’n Seal (Blue).

(9) PressA part installed using a press or driver, such as a journal, should first be coated with oil on its

outer or inner circumference so that it will go into place smoothly.(10)Ball Bearing

Do not remove a ball bearing unless it is absolutely necessary. Replace any ball bearings thatwere removed with new ones. Install bearings with the manufacturer and size marks facing out,applying pressure evenly with a suitable driver to the end of the race that contacts the press fitportion, and press it evenly over the base component.

(11)Oil Seal and Grease SealReplace any oil or grease seals that were removed with new ones, as removal generally dam-

ages seals. When pressing in a seal which has manufacturer’s marks, press it in with the marksfacing out. Seals should be pressed into place using a suitable driver, which contacts evenly withthe side of seal, until the face of the seal is even with the end of the hole.

GENERAL INFORMATION 1-3Before Servicing

(12)Seal GuideA seal guide is required for certain oil or grease seals during installation to avoid damage to

the seal lips. Before a shaft passes through a seal, apply a little oil, preferably high-temperaturegrease on the lips to reduce rubber to metal friction.

(13)Circlip and Retaining RingWhen installing circlips and retaining rings, take care to compress or expand them only enough

to install them and no more. Install the circlip with its chamfered side facing load side as well.Replace any circlips and retaining rings that were removed with new ones, as removal weakens

and deforms them. If old ones are reused, they could become detached while running, leading toa problem.

(14)LubricationEngine wear is generally at its maximum while the engine is warming up and before all the

rubbing surfaces have an adequate lubricative film. During assembly, oil or grease (whicheveris more suitable) should be applied to any rubbing surface which has lost its lubricative film. Oldgrease and dirty oil should be cleaned off. Deteriorated grease has lost its lubricative quality andmay contain abrasive foreign particles.Don’t use just any oil or grease. Some oils and greases in particular should be used only in

certain applications and may be harmful if used in an application for which they are not intended.This manual makes reference to molybdenum disulfide grease (MoS2) in the assembly of certainengine parts. Always check manufacturer recommendations before using such special lubricants.

(15)Electrical WiresAll the electrical wires are either single-color or two-color and, with only a few exceptions, must

be connected to wires of the same color. On any of the two-color wires there is a greater amountof one color and a lesser amount of a second color, so a two-color wire is identified by first theprimary color and then the secondary color. For example, a yellow wire with thin red stripes isreferred to as a "yellow/red" wire; it would be a "red/yellow" wire if the colors were reversed tomake red the main color.

(16)Replacement PartsWhen there is a replacement instruction, replace these parts with new ones every time they are

removed. There replacement parts will be damaged or lose their original function once removed.(17)Inspection

When parts have been disassembled, visually inspect these parts for the following conditionsor other damage. If there is any doubt as to the condition of them, replace them with new ones.

Abrasion Crack Hardening WarpBent Dent Scratch WearColor change Deterioration Seizure

(18)Service DataService Data terms are defined as follows:"Standards" show dimensions or performances which brand-new parts or systems have."Service Limits" indicate the usable limits. If the measurement shows excessive wear or dete-

riorated performance, replace the damaged parts.

1-4 GENERAL INFORMATIONModel Identification

FJ180V

FJ180V (KAI Model)

Model ApplicationYear Model Beginning Engine Number

2010 ∼ FJ151V FJ151VJ00001 ∼2010 ∼ FJ180V FJ180VJ00001 ∼

GENERAL INFORMATION 1-5General Specifications

FJ151V, FJ180VItem

Standard Model KAI ModelType Forced air-cooled, vertical shaft, OHV, 4-stroke gasoline engineBore × Stroke 65 mm × 54 mm (2.56 in. × 2.13 in.)Displacement 179 cm³ (10.9 cu in.)Direction of Rotation Counterclockwise facing the PTO shaftCompression Release Automatic compression releaseLow Idle Speed 1 550 rpm (r/min) (Choke Start Model)

Not specified (Priming Start Model)High Idle Speed 3 300 rpm (r/min) (Choke Start Model)

3 200 rpm (r/min) (Priming Start Model)2 950 rpm (r/min) (FJ151V Model)

Ignition System Flywheel magneto with CDIRFI Per Canada and U.S.A. requirementsStarting System Recoil starterSpark Plug NGK BPR5ESCarburetor Float type, fixed main jetAir Cleaner Dual stage element, dry typeGovernor Flyweight all speed governorLubrication System Pressure feed by positive displacement pumpOil Capacity(when engine is completely dry) 0.65 L (0.69 US qt)

Cooling System Forced air cooling by fan

Dimensions (L × W × H ) 393 mm × 317 mm × 286 mm(15.5 in. × 12.5 in. × 11.3 in.)

390 mm × 344 mm × 290 mm(15.4 in. × 13.5 in. × 11.4 in.)

Dry Weight 17.0 kg (37.5 lb) 16.9 kg (37.3 lb)Specifications are subject to change without notice.

1-6 GENERAL INFORMATIONUnit Conversion Table

Prefixes for Units:

Prefix Symbol Powermega M × 1 000 000kilo k × 1 000centi c × 0.01milli m × 0.001micro µ × 0.000001

Units of Mass:kg × 2.205 = lbg × 0.03527 = oz

Units of Volume:L × 0.2642 = gal (US)L × 0.2200 = gal (imp)L × 1.057 = qt (US)L × 0.8799 = qt (imp)L × 2.113 = pint (US)L × 1.816 = pint (imp)mL × 0.03381 = oz (US)mL × 0.02816 = oz (imp)mL × 0.06102 = cu in

Units of Force:N × 0.1020 = kgN × 0.2248 = lbkg × 9.807 = Nkg × 2.205 = lb

Units of Length:km × 0.6214 = milem × 3.281 = ftmm × 0.03937 = in

Units of Torque:N·m × 0.1020 = kgf·mN·m × 0.7376 = ft·lbN·m × 8.851 = in·lbkgf·m × 9.807 = N·mkgf·m × 7.233 = ft·lbkgf·m × 86.80 = in·lb

Units of Pressure:kPa × 0.01020 = kgf/cm²kPa × 0.1450 = psikPa × 0.7501 = cmHgkgf/cm² × 98.07 = kPakgf/cm² × 14.22 = psicmHg × 1.333 = kPa

Units of Speed:km/h × 0.6214 = mph

Units of Power:kW × 1.360 = PSkW × 1.341 = HPPS × 0.7355 = kWPS × 0.9863 = HP

Units of Temperature:

PERIODIC MAINTENANCE 2-1

2

Periodic MaintenanceTable of Contents

Periodic Maintenance Chart ................................................................................................... 2-2Torque and Locking Agent...................................................................................................... 2-3Specifications ......................................................................................................................... 2-5Special Tools .......................................................................................................................... 2-6Periodic Maintenance Procedures.......................................................................................... 2-7Fuel System......................................................................................................................... 2-7Idle Speed Adjustment (Choke Start Model)..................................................................... 2-7Idle Speed Adjustment (Priming Start Model)................................................................... 2-8Fuel System Cleanliness Inspection ................................................................................. 2-8Fuel Filter Inspection......................................................................................................... 2-9Air Cleaner Element Removal........................................................................................... 2-9Air Cleaner Element Installation........................................................................................ 2-10Air Cleaner Element Cleaning and Inspection .................................................................. 2-10Air Cleaner Housing (Case and Body) Inspection ............................................................ 2-11

Engine Top End ................................................................................................................... 2-11Cylinder Head Cleaning and Inspection............................................................................ 2-11Valve Clearance Inspection .............................................................................................. 2-12Valve Clearance Adjustment............................................................................................. 2-13Valve Seat Inspection ....................................................................................................... 2-13Valve Seat Repair ............................................................................................................. 2-14

Lubrication System .............................................................................................................. 2-17Oil Level Inspection........................................................................................................... 2-17Oil Change........................................................................................................................ 2-17Oil Filter Replacement ...................................................................................................... 2-18

Electrical System ................................................................................................................. 2-18Spark Plug Cleaning and Inspection................................................................................. 2-18Spark Plug Gap Inspection ............................................................................................... 2-18

2-2 PERIODIC MAINTENANCEPeriodic Maintenance Chart

To ensure satisfactory operation over an extended period of time, any engine requires normal main-tenance regular intervals. The Periodic Maintenance Chart shows periodic inspection and mainte-nance items and suitable intervals. The bullet mark (•) designates that the corresponding item shouldbe performed at that interval.Some adjustments require the use of special tools or other equipment. An electronic tachometer

will facilitate setting idle and running speeds.INTERVAL

OPERATIONDaily First 8

hr.Every25 hr.

Every50 hr.

Every100 hr.

Every300 hr.

Check and clean air inlet screen •Check and add engine oil •Check for fuel and oil leakage •Check for loose or lost nuts and screws •Clean air cleaner foam element (1) •Clean air cleaner paper element (1) •Tighten nuts and screws •

(First) •Change engine oil • •Clean and re-gap spark plug •Change air cleaner paper element (1) •Clean dust and dirt from cylinder andcylinder head fins (1) •Check and adjust valve clearance •Clean and lap valve seating surface •Clean combustion chamber •(1): Service more frequently under dusty conditions.: These items must be performed with the proper tools. See your authorized Kawasaki EngineDealer for service, unless you have the proper equipment and mechanical proficiency.

PERIODIC MAINTENANCE 2-3Torque and Locking Agent

The following tables list the tightening torque for the major fasteners, and the parts requiring use ofa non-permanent locking agent or silicone sealant etc.Letters used in the "Remarks" column mean:L : Apply a non-permanent locking agent.O : Apply engine oil.S : Follow the specified tightening sequence.

TorqueFastener

N·m kgf·m ft·lbRemarks

Fuel SystemGovernor Arm Clamp Nut 7.8 0.80 69 in·lbFuel Tank Cover Bolts 6.9 0.70 61 in·lbFuel Tank Bracket Bolt 6.9 0.70 61 in·lbPriming Nut 1.2 0.12 11 in·lbThrottle Valve Screw 0.70 0.07 6 in·lb LMain Jet 1.1 0.11 9.7 in·lbDrain Screw 5.4 0.55 48 in·lbFloat Chamber Mounting Bolt 9.8 1.0 48 in·lbFloat Chamber Mounting Bolt (ChokeStart Model)

9.8 1.0 39 in·lb

Cooling SystemFlywheel Bolt 42 4.3 31Fuel Tank Cover Bolts 6.9 0.70 61 in·lb

Engine Top EndCylinder Head Bolts (7T) 22 2.2 16 SCylinder Head Bolts (7N) 25 2.5 18 SCylinder Head Bolts (9N) 26 2.6 19 SValve Clearance Lock Screws 6.9 0.70 61 in·lbConnecting Rod Big End Cap Bolts 5.9 0.60 52 in·lb ORocker Arm Bolts 28 2.8 20Spark Plug 22 2.2 16Rocker Cover Mounting Bolts 5.9 0.60 52 in·lbMuffler Cover Bolt 6.9 0.70 61 in·lb

Lubrication SystemOil Drain Plug 22 2.2 16Oil Filter Cover Bolt 6.9 0.70 61 in·lb

Camshaft/CrankshaftCrankcase Cover Bolts 8.8 0.90 78 in·lb SCrankcase Cover Bolts (Cylinderside)

5.9 0.60 52 in·lb S

Connecting Rod Big End Cap Bolts 5.9 0.60 52 in·lb OValve Clearance Lock Screws 6.9 0.70 61 in·lbRocker Arm Bolts 28 2.8 20

Starter SystemRecoil Starter Mounting Bolts 6.9 0.70 61 in·lbBrake Arm Mounting Bolt 9.3 0.95 82 in·lbBrake Lever Assembly Mounting Bolt 6.9 0.70 61 in·lb

2-4 PERIODIC MAINTENANCETorque and Locking Agent

TorqueFastener


Electrical SystemFlywheel Bolt 42 4.3 31Spark Plug 22 2.2 16Kill Switch Bolt 1.5 0.15 13 in·lbThe table below, relating tightening torque to thread diameter, lists the basic torque for the bolts and

nuts. Use this table only for the bolts and nuts which do not require a specific torque value. All of thevalues are for use with dry solvent-cleaned threads.

Basic Torque for General FastenersThreads Diameter Torque

(mm) N·m kgf·m ft·lb4 2.0 0.20 17 in·lb5 3.4 0.35 30 in·lb6 5.9 0.60 52 in·lb8 15 1.5 1110 20 2.0 15

PERIODIC MAINTENANCE 2-5Specifications

Item StandardFuel SystemIdle Speed (1) :Low Idle Speed:Choke Start Model 1 550 r/min(rpm)Priming Start Model Not specified

High Idle Speed:Choke Start Model 3 300 r/min (rpm)Priming Start Model 3 200 r/min (rpm)FJ151V Model 2 950 r/min (rpm)

Air Cleaner:Type Dual stage filtration systemCleaner:First Foam elementSecond Paper element

Engine Top EndCylinder Head Warp Service Limit: 0.03 mm (0.001 in.)Valve Clearance:Exhaust 0.10 ∼ 0.15 mm (0.004 ∼ 0.006 in.)Inlet 0.10 ∼ 0.15 mm (0.004 ∼ 0.006 in.)

Valve Seating Surface Angle:Exhaust 45°Inlet 45°

Valve Seating Surface Width:Exhaust 0.6 ∼ 0.9 mm (0.024 ∼ 0.035 in.)Inlet 0.6 ∼ 0.9 mm (0.024 ∼ 0.035 in.)

Lubrication SystemEngine Oil:Type SF, SG, SH or SJ classViscosity SAE30, SAE10W-30Capacity 0.65 L (0.69 US qt)Level Operating range (grid area) on dipstick

Electrical SystemSpark Plug Gap 0.75 mm (0.030 in.)(1) Idle speeds may vary depending on each equipment. Refer to the equipment specification.

2-6 PERIODIC MAINTENANCESpecial Tools

Valve Seat Cutter, 45° - 27.5:57001-1114

Valve Seat Cutter, 32° - 25:57001-1118

Valve Seat Cutter, 32° - 28:57001-1119

Valve Seat Cutter Holder Bar:57001-1128

Oil Filter Wrench:57001-1249

Valve Seat Cutter Holder, 6:57001-1360

PERIODIC MAINTENANCE 2-7Periodic Maintenance Procedures

Fuel SystemIdle Speed Adjustment (Choke Start Model)

CAUTIONDo not adjust idle speed with the air cleaner re-moved.

High Idle Speed Adjustment•Start and warm up the engine without load.• Tighten the control panel mounting bolts [A] temporarily.

•Move the throttle lever [A] at a dash to the high idle po-sition, align bend part of throttle lever with hole of controlpanel [B] and insert the 6 mm (0.24 in.) diameter pin orbolt [C] through hole. When installing, fit the bend part ofthe throttle lever and the 6 mm (0.24 in.) diameter pin orbolt.• Adjust the idle speed for specified rpm by moving controlpanel, and tighten the control panel mounting bolts se-curely.

High Idle Speed3 300 r/min (rpm)2 950 r/min (rpm) (FJ151V Model)

•Remove the 6 mm (0.24 in.) diameter pin or bolt from thecontrol panel.

Low Idle Speed Adjustment•Move the throttle lever at a dash to the low idle position.• Adjust the idle speed set screw [A] on the carburetor toobtain the specified rpm.

Low Idle Speed1 550 r/min (rpm)

•Stop the engine.

2-8 PERIODIC MAINTENANCEPeriodic Maintenance Procedures

Choke Adjustment•Stop the engine.•Move the throttle lever [A] at a dash to the high idle po-sition, align bend part of throttle lever with hole of controlpanel [B] and insert the 6 mm (0.24 in.) diameter pin orbolt [C] through hole. When installing, fit the bend part [D](carburetor side) of the throttle lever and the 6 mm (0.24in.) diameter pin or bolt.• Adjust the clearance (0.5 ∼ 1.5 mm, 0.02 ∼ 0.06 in.)between the bend part (opposite carburetor side) of thethrottle lever and the screw end [E] of the control panelby turning the screw.

•Remove the 6 mm (0.24 in.) diameter pin or bolt from thecontrol panel. After removing, move the choke lever ofthe control panel and make sure that the position of thechoke lever [A] on the carburetor will be the opened orclosed positions.

Idle Speed Adjustment (Priming Start Model)High Idle Speed Adjustment

CAUTIONDo not adjust high idle speed with the air cleanerremoved.

•Start and warm up the engine thoroughly.

WARNINGAlways keep your hands clear of the moving parts.

•Move the throttle lever at a dash to the high idle position.• Loosen the control panel mounting bolts [A] enough tomove the control panel assembly.•Carefully move the control panel assembly right or left toobtain the specified high idle speed.

High Idle Speed3 200 r/min (rpm)

•Tighten the mounting bolts.Fuel System Cleanliness Inspection

WARNINGGasoline is extremely flammable and can be ex-plosive under certain conditions. Turn the engineswitch stop position. Do not smoke. Make sure thearea is well-ventilated and free from any source offlame or sparks, this includes any appliance with apilot light.


Choke Start Model•Place a suitable container [B] under the bolt [A] of thecarburetor.• Loosen the bolt to drain the carburetor and check to seeif water or dirt has accumulated in the carburetor.• Tighten the bolt.Torque - Float Chamber Mounting Bolt: 4.5 N·m (0.45

kgf·m, 39 in·lb)

• If any water or dirt is found, clean the carburetor and thefuel tank (see Carburetor Cleaning, Fuel Tank Cleaningin the Fuel System chapter).

Priming Start Model•Place a suitable container [B] under the drain screw [A] ofthe carburetor.• Loosen the drain screw to drain the carburetor and checkto see if water or dirt has accumulated in the carburetor.• Tighten the drain screw.Torque - Drain Screw: 5.4 N·m (0.55 kgf·m, 48 in·lb)

• Install the primer pipe in the tube (see Priming Pump In-stallation in the Fuel System chapter).• If any water or dirt is found, clean the carburetor and thefuel tank (see Carburetor Cleaning, Fuel Tank Cleaningin the Fuel System chapter).

Fuel Filter Inspection•Visually inspect the fuel filter.If the filter is clear with no signs of dirt or other contami-nation, the replacement of the filter is not necessary.If the filter is dark or looks dirty, replace it with a new one.Also check the rest of the fuel system for contamination.•Check the O-ring at the tank drain for damage. Replacethe O-ring with a new one if it is damaged.

Air Cleaner Element Removal•Remove the nut [A].


•Remove the air cleaner case [A].

• Remove:Paper Element [A]Foam Element [B]

Air Cleaner Element Installation• Install:Foam ElementPaper Element• Install the hollow [A] of the air cleaner case to fit the pro-jection [B] of the air cleaner body.

• Tighten the nut [A].

Air Cleaner Element Cleaning and InspectionNOTE

In dusty areas, clean the elements more frequently thanthe recommended intervals.

WARNINGBecause of the danger of highly flammable liquids,do not use gasoline or a low-flash point solvent toclean the element.


•Remove the paper element and the foam element (seeAir Cleaner Element Removal).• Clean the foam element [A] in a bath of detergent and wa-ter, and let the element air-dry thoroughly before installingit.

• Clean the paper element [A] by tapping it gently on a flatsurface to remove dust. If the element is very dirty, re-place it with a new one.

CAUTIONDo not use compressed air to clean the paper ele-ment. Do not oil the paper or foam element.

Air Cleaner Housing (Case and Body) Inspection•Clean the housing with detergent and water and dry itthoroughly.•Check the housing for deformation or other damage. Sealthe housing well and permit only filtered air to reach thecarburetor.If the housing is damaged, replace the housing with a newone.•Check that no foreign material is obstructing the air pas-sage.

Engine Top EndCylinder Head Cleaning and Inspection•Remove the cylinder head (see Cylinder Head AssemblyRemoval in the Engine Top End chapter).• Scrape the carbon deposits from the cylinder head andthe exhaust port with a suitable tool [A].• To avoid gouging, use scrapers that material will not dam-age the cylinder head and the exhaust port.• Clean the cylinder head in a bath of high-flash point sol-vent and dry it with compressed air.

WARNINGClean the cylinder head in a well ventilated area,and take care that there are no sparks or flame any-where near the working area, this includes any ap-pliance with a pilot light. Do not use gasoline or alow-flash point solvent to clean the cylinder head.A fire or explosion could result.


• Lay a straight edge [A] across the mating surface of thehead at several different points, and measure the warp byinserting a thickness gauge [B] between the straight edgeand the cylinder head.If the warp exceeds the service limit, repair the matingsurface. Replace the cylinder head with a new one if themating surface is badly damaged or warped.

Cylinder Head WarpService Limit: 0.03 mm (0.001 in.)

•Check the cylinder head for cracks or other damage.•Cracks not visible to the eye may be detected by using ametal crack detection system (Visual color check: com-monly found at automotive parts tore).• If a crack is present in the cylinder head, replace it with anew one.• Inspect the mating surface for burrs and nicks.Valve Clearance Inspection

NOTEValve clearance must be checked when the engine iscold (at room temperature).

•Remove the rocker cover (see Cylinder Head AssemblyRemoval in the Engine Top End chapter).• Place the piston at the top dead center (TDC) of the com-pression stroke end by turning the crankshaft counter-clockwise.

•Check the valve clearance.Using a thickness gauge [A], measure the valve clearancebetween the rocker arm [B] and the valve stem end.If the valve clearance is not correct, adjust it.

Valve ClearanceStandard:Exhaust 0.10 ∼ 0.15 mm (0.004 ∼ 0.006 in.)Inlet 0.10 ∼ 0.15 mm (0.004 ∼ 0.006 in.)


Valve Clearance Adjustment•Since valve repairs change the valve clearance, adjustthe valve clearance to the specification.• Assemble the cylinder head and install the cylinder headassembly on the block (see Cylinder Head Assembly In-stallation in the Engine Top End chapter).• Turn the crankshaft to the proper direction until the pistonis at the TDC of the compression stroke end.• Loosen the lock screws [A] and the valve clearance ad-justing nuts [B].• Insert a 0.10 mm (0.004 in.) thickness gauge [C] betweenthe rocker arm and valve stem, and tighten the adjustingnut until the thickness gauge begins to bind between therocker arm and valve stem end. Use a sweeping motionwith the thickness gauge while making this adjustment.

Valve ClearanceStandard:Exhaust 0.10 ∼ 0.15 mm (0.004 ∼ 0.006 in.)Inlet 0.10 ∼ 0.15 mm (0.004 ∼ 0.006 in.)

•Holding the adjusting nut with a wrench, tighten the lockscrew to the specified torque.Torque - Valve Clearance Lock Screws: 6.9 N·m (0.70

kgf·m, 61 in·lb)

•Do not overtighten the valve clearance lock screws.• After adjusting the valve clearance, measure the valveclearance again. Readjust the valve clearance if neces-sary.

Valve Seat Inspection•Remove the valve (see ValveMechanismRemoval/Instal-lation in the Engine Top End chapter).• Inspect the valve seats for damage.If the seats are warped or distorted beyond recondition-ing, replace the cylinder head with a new one.•Reface pitted or worn valve seats. Lap the valves to theseats after refacing.•Coat the valve seat with machinist’s dye.• Push the valve into the guide.•Rotate the valve against the seat with a lapping tool.• Pull the valve out, and check the seating pattern on thevalve head. It must be the correct width [A] and even allthe way around.


NOTEThe valve stem and guide must be in good condition orthis check will not be valid.

Good [A]Too Wide [B]Too Narrow [C]Uneven [D]If the valve seating pattern is not correct, repair the seat.

Valve Seating Surface WidthStandard:Exhaust 0.6 ∼ 0.9 mm (0.024 ∼ 0.035 in.)Inlet 0.6 ∼ 0.9 mm (0.024 ∼ 0.035 in.)

Valve Seat Repair•Follow the manufacturer’s instructions for use of valveseat cutters.Special Tools - Valve Seat Cutter Holder Bar : 57001-1128

Valve Seat Cutter Holder- 6.0 : 57001-1360Exhaust Valve:Valve Seat Cutter, 45° - 27.5 : 57001-1114Valve Seat Cutter, 32° - 25.0 : 57001-1118Inlet Valve:Valve Seat Cutter, 45° - 27.5 : 57001-1114Valve Seat Cutter, 32° - 28.0 : 57001-1119

If the manufacturer’s instructions are not available, usethe following procedure.

Seat Cutter Operating Cares:1. This valve seat cutter is designed only for valve seat re-pair. Do not use the valve seat cutter for other purposes.

2. Do not drop or hit the valve seat cutter, or the diamondparticles may fall off.

3. Be sure to apply engine oil to the valve seat cutter beforegrinding the seat surface. Also wash off ground particlessticking to the cutter with washing oil.

NOTEDo not use a wire brush to remove the metal particlesfrom the cutter. It will take off the diamond particles.

4. Setting the valve seat cutter holder [A] in position, op-erate the cutter [B] with one hand [C]. Do not apply toomuch force to the diamond portion.

NOTEPrior to grinding, apply oil to the cutter, and during theoperation wash off any ground particles sticking to thecutter with washing oil.

5. After use, wash the cutter with washing oil and apply athin layer of engine oil before storing.


Marks Stamped on the Cutter:The marks stamped on the back of the cutter represent thefollowing.

1 Cutter number, selected from 1 to 1230° Cutter angle [A]37.5 Cutter diameter of cutter [B]KS8B Manufactured lot number

Operating Procedures:•Clean the seat area carefully.• Recondition the valve seats with the valve seat cutters(45°, 32°) and lap the valves.•Check the seats for good contact all the way around withmachinist’s dye.•Measure the seat width [A]. If it is more than the standardwidth, reface the seating surface.• If the valve seating pattern is not correct, repair the seat.

• Coat the seat with machinist’s dye.• Fit a 45° seat cutter [A] to the holder and slide it into thevalve guide.Resurface the valve seat with a 45° cutter, removing onlyenough material to produce a smooth and concentricseat.

CAUTIONDo not grind the seat too much. Overgrinding willreduce valve clearance by sinking the valve into thehead. If the valve sinks too far into the head, it willbe impossible to adjust the clearance, and the cylin-der head must be replaced. Do not turn the cuttercounterclockwise or drop it against the seat, or itwill be dulled.


•Use a 32° seat cutter [A] to narrow the seat width to thestandard width.Turn the seat cutter one turn at a time while pressing downvery lightly. Check the seat width after each turn.

CAUTIONThe 32° cutter removes the material very quickly.Check the seat width frequently to prevent overgrinding.

NOTEKeep the seat width as close as possible to the standardwidth.

•Make a light contact on the valve seat with the 45° cutterto remove any possible burrs at the edge of the seat.• After resurfacing the seat, inspect for even valve seating.Apply a machinist’s dye to the valve face, insert thevalve, and snap it closed against the seat several times.The valve surface should show good contact all the wayaround. Be sure the valve seat is centered on the valveface. The position of the valve in the seat is evident afterlapping the valve.If the seat does not make proper contact, lap the valveinto seat with a lapper.

•Coat the valve face sparingly with a fine lapping com-pound.•Use the lapper [A], to grip the top of the valve [B]. Rotatethe valve in a circular motion to lap the valve to the seat.• Lift the valve slightly from the seat every 8 to 10 strokes,continue lapping operation until a uniform ring appearsaround entire surface of the valve face.

•When lapping is completed, wash all parts in solvent toremove lapping compound. Dry the parts thoroughly.•Note the position of the lapping mark on the valve face.The lapping mark should appear on or near the center ofthe valve face.•When the engine is assembled, be sure to adjust the valveclearances (see Valve Clearance Adjustment).


Lubrication SystemOil Level Inspection•Place the engine on a level surface.•Remove the oil filler cap [A] and wipe its dipstick [B] witha clean cloth.• Insert the dipstick into the gauge hole [C] without screwingit in, then check the oil level.

• The oil level should be the operating range [A] (grid area)on the dipstick.If the oil level is "ADD" range [B], add enough engine oilto bring oil level to the operating range.

CAUTIONDo not add more oil above the operating range. Ex-cess oil will cause a smoking condition.

Use the same type and make of oil that is already in theengine.

NOTEIf the engine oil type and make are unknown, use anybrand of the specified oil to top up the level in preferenceto running the engine with the oil level low. Then at yourearliest convenience, change the oil completely.

If the oil level is "FULL" range [C], drain the excess oil byloosening the drain plug.

Oil Change•Change the oil after first 8 hours of operation. Thereafterchange oil every 50 hours.• Start and warm up the engine to drain the oil easily.• Stop the engine.• Place the engine on a level surface.• Place a suitable container under the engine.•Remove the drain plug [A] and drain the oil.

WARNINGBe careful of hot oil when drained. It may be hotenough to burn you severely.

•Tighten the drain plug.Torque - Oil Drain Plug : 22 N·m (2.2 kgf·m, 16 ft·lb)


•Remove the oil filler cap and pour in the specified typeand amount of oil.

Engine OilType: SF, SG, SH or SJ ClassViscosity: SAE30, SAE10W-30Capacity: 0.65 L (0.69 US qt)

Oil Filter Replacement•Drain the engine oil (see Oil Change).•Using a strap wrench or oil filter wrench, remove the oilfilter [A].Special Tool - Oil Filter Wrench: 57001-1249When unscrewing the oil filter, place a suitable containerbeneath the oil filter to receive oil from the oil filter and oilpassages in the engine. Turn the filter counterclockwiseto remove it.• Replace the oil filter [A] with a new one.• Apply light film of engine oil to the seal [B].• Install a oil filter.Turn the oil filter until the seal contacts mounting surface[C] of the engine. Then turn the oil filter BY HAND(S) 3/4turn more.•Run the engine at slow idle speed 2 minutes. Check forleaks around the engine.• Stop the engine. Check the oil level (see Oil Level Inspec-tion).

Electrical SystemSpark Plug Cleaning and Inspection•Remove the spark plug (see Spark Plug Removal in theElectrical System chapter).If the plug is oily or has carbon build up on it, clean theplug using a high-flash point solvent and a wire brush orother suitable tool.If the spark plug electrodes are corroded or damaged, or ifthe insulator is cracked, replace the plug with a new one.Use the standard spark plug or its equivalent.Insulator [A]Center Electrode [B]Plug Gap [C]Side Electrode [D]

Spark Plug Gap Inspection•Measure the gap with a wire-type thickness gauge.If the gap is not correct, carefully bend the side electrodewith a suitable tool to obtain the correct gap.

Spark Plug GapStandard: 0.75 mm (0.030 in.)

FUEL SYSTEM 3-1

3

Fuel SystemTable of Contents

Exploded View................................... 3-2Specifications .................................... 3-6Governor Link Mechanism (ChokeStart Model) .................................... 3-7Control Panel Assembly Removal 3-7Control Panel AssemblyInstallation ................................. 3-7

Governor Arm Removal ............... 3-7Governor Link Mechanism (PrimingStart Model) .................................... 3-8Control Panel Assembly Removal 3-8Control Panel AssemblyInstallation ................................. 3-8

Governor Arm Removal ............... 3-8Governor Link Mechanism................. 3-9

Governor Arm Installation ............ 3-9Governor Assembly Inspectionand Removal ............................. 3-9

Governor Assembly Installation ... 3-10Governor Shaft Removal ............. 3-10Governor Shaft Installation .......... 3-10

Carburetor ......................................... 3-11Fuel and Air Flow (Choke StartModel) ....................................... 3-11

Fuel and Air Flow (Priming StartModel) ....................................... 3-12

Idle Speed Adjustment................. 3-12High Altitude Operation................ 3-13Main Jet Replacement ................. 3-13Fuel System CleanlinessInspection.................................. 3-14

Carburetor Removal..................... 3-14Carburetor Installation.................. 3-15Carburetor Disassembly/Assem-bly ............................................. 3-16

Carburetor Cleaning..................... 3-18Carburetor Inspection .................. 3-19

Priming Pump ................................... 3-21Priming Pump Removal ............... 3-21Priming Pump Installation ............ 3-21

Inlet Manifold (Choke Start Model) .... 3-22Inlet Manifold Removal ................ 3-22Inlet Manifold Installation ............. 3-22

Inlet Manifold (Priming Start Model) .. 3-23Inlet Manifold Removal ................ 3-23Inlet Manifold Installation ............. 3-23

Inlet Manifold ..................................... 3-24Inlet Manifold Inspection .............. 3-24

Fuel Tank........................................... 3-25Fuel Tank Removal ...................... 3-25Fuel Tank Installation ................... 3-25Fuel Tank Cleaning ...................... 3-25

Fuel Filter........................................... 3-26Fuel Filter Inspection.................... 3-26

Air Cleaner......................................... 3-27Air Cleaner Element Removal ..... 3-27Air Cleaner Element Installation... 3-27Air Cleaner Element Cleaning andInspection.................................. 3-27

Air Cleaner Body Removal(Priming Model)......................... 3-27

Air Cleaner Body Installation........ 3-27Air Cleaner Body Removal(Choke Model)........................... 3-27

Air Cleaner Body Installation........ 3-28Air Cleaner Housing (Case andBody) Inspection ....................... 3-28

3-2 FUEL SYSTEMExploded View

FUEL SYSTEM 3-3Exploded View

TorqueNo. Fastener


1 Governor Arm Clamp Nut 7.8 0.80 69 in·lb2 Fuel Tank Bracket Bolt 6.9 0.70 61 in·lb3. Choke Start ModelR: Replacement Parts

3-4 FUEL SYSTEMExploded View

FUEL SYSTEM 3-5Exploded View

TorqueNo. Fastener


1 Throttle Valve Screw 0.70 0.07 6 in·lb L2 Main Jet 1.1 0.11 9.7 in·lb3 Float Chamber Mounting Bolt 9.8 1.0 87 in·lb

4 Float Chamber Mounting Bolt(Choke Start Model) 9.8 1.0 87 in·lb

5. Choke Start ModelL: Apply a non-permanent locking agent.R: Replacement Parts

3-6 FUEL SYSTEMSpecifications

StandardItem

FJ151V, FJ180VCarburetorMake/Type NIKKI 6C1020-671 (Choke Model)

NIKKI 6C1020-681 (Priming Model)Throttle Bore Diameter 20 mm (0.79 in.)Venturi Diameter 14 mm (0.55 in.)Main Jet (MJ) #81Pilot Jet (PJ) #40Pilot Air Screw Turns Out (PS) 2 3/4(Idle mixture screw turns out)

Float Level Float parallel to carburetor bodyIdle Speed (1):Low 1 550 r/min (rpm) (Choke Start Model)

Not specified (Priming Start Model)High 3 300 r/min (rpm) (Choke Start Model)

3 200 r/min (rpm) (Priming Start Model)Air CleanerType Dual stage filtration systemPre-cleaner Foam elementSecond-stage Cleaner Paper element

FuelFuel Requirement Unleaded regular grade gasoline

GovernorType Flyweight all speed governor

(1) Idle speeds may vary depending on each mounting equipment. Refer to the mounting equipmentspecification.

FUEL SYSTEM 3-7Governor Link Mechanism (Choke Start Model)

Control Panel Assembly Removal•Remove:Air Cleaner Elements (see Air Cleaner Element Re-moval)Recoil Starter (see Recoil Starter Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal)Control Panel Mounting Bolts [A]

•Remove the control panel [B] unhooking the governorspring [A] end loop at the panel bracket.

Control Panel Assembly InstallationIf any part is worn or damaged, replace the control panelwith a new one.• Install the control panel.• Tighten the control panel mounting bolts.• Hook the governor spring end loop [A] at the panel bracket[B].• After installation, adjust the idle speed to the specifica-tions (see Idle Speed Adjustment in the Periodic Mainte-nance chapter).

Governor Arm Removal•Remove:Control Panel Assembly• Loosen the clamp nut [A] and take off the governor arm[B].• Unhook the throttle link rod spring [C] end loop and clearthe throttle link rod lower end [D].

3-8 FUEL SYSTEMGovernor Link Mechanism (Priming Start Model)

Control Panel Assembly Removal•Remove:Air Cleaner Elements (see Air Cleaner Element Re-moval)Recoil Starter (see Recoil Starter Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal)Control Panel Mounting Bolts [A]

•Remove the control panel [B] unhooking the governorspring [A] end loop at the panel bracket.

Control Panel Assembly InstallationIf any part is worn or damaged, replace the control panelwith a new one.• Install the control panel.• Tighten the control panel mounting bolts.• Hook the governor spring end loop [A] at the panel bracket[B].• After installation, adjust the idle speed to the specifica-tions (see Idle Speed Adjustment in the Periodic Mainte-nance chapter).

Governor Arm Removal•Remove:Control Panel Assembly• Loosen the clamp nut [A] and take off the governor arm[B].• Unhook the throttle link rod spring [C] end loop and clearthe throttle link rod lower end [D].

FUEL SYSTEM 3-9Governor Link Mechanism

Governor Arm Installation• Install the governor arm [A] onto the governor shaft [B]temporarily.• Be sure the link spring [C] around the throttle link rod [D] isin place and that it pulls the governor arm and the throttlelever [E] toward each other.• Loosen the clamp nut [F] on the governor arm enough tomove the governor shaft.Choke Start Model [H]; install the governor link and springinto the same link hole of the governor arm.Priming Start Model [I]; install the governor link and springinto the each link hole of the governor arm.• Turn the top end of the governor arm counterclockwise[G] to fully open the carburetor throttle valve and hold itthere.• Turn the governor shaft counterclockwise, fully turn theshaft to end of its travel.There should be no gap between the governor arm andthe snap pin on the governor shaft.• Tighten the clamp nut.Torque - Governor Arm Clamp Nut: 7.8 N·m (0.80 kgf·m, 69

in·lb)

• Install the control panel assembly, and connect the gov-ernor arm with the governor spring.

Governor Assembly Inspection and Removal•Remove the crankcase cover (see Crankcase Cover Re-moval in the Camshaft/Crankshaft chapter).• Visually check the governor assembly as built in thecrankcase cover for damage or wear.

CAUTIONDo not remove the governor assembly unless theparts are to be replaced. Do not reuse the partsonce they are removed.

•When removing the governor gear assembly [A] for re-placing, use two screw drivers [B] of an appropriate size.

CAUTIONProtect the gasket-mount surface of the crankcasecover when removing the governor assembly withthe screw drivers.

3-10 FUEL SYSTEMGovernor Link Mechanism

Governor Assembly Installation• Instal the sleeve [A] on the governor assembly [B].

CAUTIONFirst install the sleeve. The sleeve cannot be in-stalled after the governor gear assembly has beeninstalled.

•To install, first place the thrust washer [C] on the boss ofthe shaft [D]. Then, install the governor assembly (withthe sleeve attached) on the shaft so that the step [E] isfitted securely in the groove [F].• After installing the assembly, turn the governor by handto make sure that the governor weight [G] and the sleevemove smoothly.

Governor Shaft Removal•Remove:Air Cleaner Elements (see Air Cleaner Element Re-moval)Recoil Starter (see Recoil Starter Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal)Governor Arm (see Governor Arm Removal)Flywheel (see Flywheel Removal in the Electrical Sys-tem chapter)Crankcase Cover (see Crankcase Cover Removal in theCamshaft/Crankshaft chapter)Crankshaft (see Crankshaft Removal in theCamshaft/Crankshaft chapter)

•Remove:Snap Pin [A]Governor Shaft [B]Washer [C]

Governor Shaft Installation•Apply engine oil to the governor shaft.• Install:Washer [A]Governor Shaft [B]Snap Pin [C]•Check that the governor shaft moves freely in its operatingrange.

FUEL SYSTEM 3-11Carburetor

Fuel and Air Flow (Choke Start Model)The main system of the carburetor consists of the main

jet [A], the main nozzle [B], and the main air passage [C](main air jet [D]). The main system meters fuel to the en-gine during moderate to high load conditions. Fuel flowsthrough the main jet and into the main nozzle, where it isjoined by air from the main air passage (main air jet). Theresulting mixture flows out the end of the main nozzle intothe carburetor bore, where it is atomized by the high speedair flow, and carried into the engine.By closing the choke valve, the engine start system of

the carburetor reduces the inlet air volume, increases thevacuum pressure in the inlet stroke and flows out the fuel ofsuitable quantity from the pilot line and the main line of thecarburetor.

The pilot system includes the pilot jet [E], the pilot screw[F] (idle mixture screw), the pilot air jet [G], the pilot outlet[H], and the bypass holes [I]. The pilot system meters thefuel/air mixture while the engine is idling and running un-der a light load. Under these conditions there is very littleair flow through the carburetor bore, so little that it is notenough to draw fuel through the main system of the car-buretor and atomize it. Instead, the fuel is drawn throughthe pilot system, since the nearly closed throttle valve [J]causes high speed air flow past the pilot outlet and bypassholes (even at low engine speed).Fuel flow in the pilot system is metered by the pilot jet. Air

for better atomization is admitted via the pilot air jet in themouth of the carburetor. The fuel/air mixture passes intothe bore of the carburetor side stream of the throttle valvethrough the bypass holes and pilot outlet. While the throt-tle valve is almost closed, it covers the small bypass holesopening into the bore from the pilot system. As the throttlevalve begins to open, it uncovers the bypass holes, allow-ing more fuel/air mixture to flow. The extra flow is neededbecause the engine starts to run faster as the throttle isopened. The pilot screw controls the amount of fuel/airmixture allowed through the pilot outlet, but does not me-ter the bypass holes. A moderate amount of air comes inaround the throttle valve at idle, so adjusting the pilot screwchanges the fuel/air ratio. Turning the pilot screw (idle mix-ture screw) out (counterclockwise) enriches the mixture;turning it in (clockwise) leans the mixture.Main Fuel Flow →Pilot Fuel Flow ⇒

3-12 FUEL SYSTEMCarburetor

Fuel and Air Flow (Priming Start Model)The main system of the carburetor consists of the main

jet [A], the main nozzle [B], and the main air passage [C](main air jet [D]). The main system meters fuel to the en-gine during moderate to high load conditions. Fuel flowsthrough the main jet and into the main nozzle, where it isjoined by air from the main air passage (main air jet). Theresulting mixture flows out the end of the main nozzle intothe carburetor bore, where it is atomized by the high speedair flow, and carried into the engine.In the engine system of the carburetor, pressurized fuel

flows through the main jet by operating the priming pumpand the fuel of suitable quantity flows out from the mainnozzle.

The pilot system includes the pilot jet [E], the pilot screw[F] (idle mixture screw), the pilot air jet [G], the pilot outlet[H], and the bypass holes [I]. The pilot system meters thefuel/air mixture while the engine is idling and running un-der a light load. Under these conditions there is very littleair flow through the carburetor bore, so little that it is notenough to draw fuel through the main system of the car-buretor and atomize it. Instead, the fuel is drawn throughthe pilot system, since the nearly closed throttle valve [J]causes high speed air flow past the pilot outlet and bypassholes (even at low engine speed).Fuel flow in the pilot system is metered by the pilot jet. Air

for better atomization is admitted via the pilot air jet in themouth of the carburetor. The fuel/air mixture passes intothe bore of the carburetor side stream of the throttle valvethrough the bypass holes and pilot outlet. While the throt-tle valve is almost closed, it covers the small bypass holesopening into the bore from the pilot system. As the throttlevalve begins to open, it uncovers the bypass holes, allow-ing more fuel/air mixture to flow. The extra flow is neededbecause the engine starts to run faster as the throttle isopened. The pilot screw controls the amount of fuel/airmixture allowed through the pilot outlet, but does not me-ter the bypass holes. A moderate amount of air comes inaround the throttle valve at idle, so adjusting the pilot screwchanges the fuel/air ratio. Turning the pilot screw (idle mix-ture screw) out (counterclockwise) enriches the mixture;turning it in (clockwise) leans the mixture.Main Fuel Flow →Pilot Fuel Flow ⇒

Idle Speed Adjustment•Refer to the Idle Speed Adjustment in the Periodic Main-tenance chapter.


High Altitude OperationAt high altitude, the standard carburetor air-fuel mixture

will be excessively rich. Performance will decrease, andfuel consumption will increase. High altitude performancecan be improved by installing a smaller diameter main jet inthe carburetor and correct idle speed.

NOTEThemain jet high altitude kits are available for the equip-ment used in the high altitudes. The main jet numbersare stamped on the ends of the main jets.

High Altitude Main JetAltitude Main Jet No.

0 ∼ 1 000 m (0 ∼ 3 300 ft) #81 (92063-2497)1 000 ∼ 2 000 m (3 300 ∼ 6 600 ft) #79 (92063-2498)2 000 m (6 600 ft) and higher #77 (92063-2499)

Main Jet Replacement•Place the engine on a level surface.•Drain the fuel in the carburetor completely by unscrewingthe float chamber mounting bolt [A] at the bottom of thefloat chamber.•Remove the carburetor (see Carburetor Removal).• Unscrew the float chamber mounting bolt [A] and take offthe float chamber [B] and the gasket.

• Using a properly sized blade screw driver, carefully re-place the main jet [A] with a new one for altitude expected.• Tighten the main jet to the specification (see CarburetorDisassembly/Assembly Notes).• Install the float chamber and the gasket.• Tighten the float chamber mounting bolt and the drainscrew.Torque - Float Chamber Mounting Bolt: 9.8 N·m (1.0 kgf·m,

87 in·lb)Drain Screw: 5.4 N·m (0.55 kgf·m, 48 in·lb)

•For Choke Start model; note the following.• Place the engine on a level surface.•Drain the fuel in the carburetor completely by unscrewingthe float chamber mounting bolt [A] at the bottom of thefloat chamber.•Remove the carburetor (see Carburetor Removal).• Take off the float chamber [B] and the gasket.


•Using a properly sized blade screw driver, carefully re-place the main jet [A] with a new one for expected altitude.• Tighten the main jet to the specification (see CarburetorDisassembly/Assembly Notes).• Install the float chamber and the gasket.• Tighten the float chamber mounting bolt.Torque - Float Chamber Mounting Bolt: 9.8 N·m (1.0 kgf·m,

87 in·lb)

•For Priming Start model; note the following.• Place the engine on a level surface.•Remove the tube from the primer pipe.•Drain the fuel in the carburetor completely by unscrewingthe float chamber mounting bolt [A] at the bottom of thefloat chamber.•Remove the carburetor (see Carburetor Removal).• Take off the float chamber [B] and the gasket.

• Using a properly sized blade screw driver, carefully re-place the main jet [A] with a new one for expected altitude.• Tighten the main jet to the specification (see CarburetorDisassembly/Assembly Notes).• Install the float chamber and the gasket.• Tighten the float chamber mounting bolt.Torque - Float Chamber Mounting Bolt: 9.8 N·m (1.0 kgf·m,

87 in·lb)

Fuel System Cleanliness Inspection•Refer to the Fuel System Cleanliness Inspection in thePeriodic Maintenance chapter.

Carburetor RemovalWARNING

Gasoline is extremely flammable and can be ex-plosive under certain conditions. Turn the engineswitch stop position. Do not smoke. Make sure thearea is well-ventilated and free from any source offlame or sparks, this includes any appliance with apilot light.

•Place a suitable container beneath the fuel hose.•Disconnect the fuel hose from the carburetor.• Drain the fuel in the carburetor completely by unscrewingthe drain screw at the bottom of the float chamber.•Remove the inlet manifold (see Inlet Manifold Removal).• Remove the carburetor.• Unhook the throttle link spring [B] and throttle link rod [C]at the throttle shaft lever [A] top end with a long nosepliers.


Carburetor Installation•Clean the mating surfaces of the carburetor and the inletmanifold, and fit the new gaskets.• Take care not to bend the throttle during installation. Makesure the link spring around the throttle link rod is in placeand that it pulls the governor arm and carburetor throttleshaft lever toward each other.• Adjust:Idle Speed (see Idle Speed Adjustment in the PeriodicMaintenance chapter)


Carburetor Disassembly/Assembly•Refer to the illustration shown for disassembly and as-sembly.• There are several passage plugs (ball plugs) in the car-buretor body. Do not remove them.•Before disassembly, mark the outside of throttle valve forassembling them.•Replace the pilot screwwith a new one in accordance withthe following procedure if necessary.Carefully mark the position of the pilot screw on the carbu-retor body so that it can be installed and set to its originalposition later.Turn the pilot screw clockwise and count the number ofturns until screw is gently seated in the pilot passage.Record the number of turns needed to closed the screw.Turn out the pilot screw to replace it with a new one.Install the new pilot screw until the screw is gentlyseated. Then open the screw the same number of turnsas recorded prior to removal.Align the pilot screw with the mark on the carburetor bodyto install, taking care not to turn the pilot screw.• Install the throttle valve on the shaft as the outside markof them facing out side.•Drive the float pin into the carburetor body from the pilotscrew side.• Assemble carburetor parts with recommended tighteningtorque (see Exploded View).1. Throttle Valve Screw2. Throttle Valve3. Throttle Shaft4. Seal5. Screw6. Spring7. Plug8. Needle Jet9. Hose10. Main Jet11. Float12. Float Valve13. Float Pin14. Gasket15. Gasket16. Float Chamber17. Gasket18. Float Chamber Mounting Bolt19. Priming Pump20. Priming Pump Cover21. Screw


•For Choke Start model1. Throttle Valve Screw2. Throttle Valve3. Throttle Shaft4. Seal5. Screw6. Spring7. Plug8. Needle Jet9. Choke Valve10. Choke Shaft11. Seal12. Main Jet13. Float14. Float Valve15. Float Pin16. Gasket17. Float Chamber18. Gasket19. Float Chamber Mounting Bolt


Carburetor CleaningWARNING

Clean the carburetor in a well ventilated area, andtake care that there is no sparks or flame anywherenear the working area, this includes any appliancewith a pilot light. Because of the danger of highlyflammable liquids, do not use gasoline or low-flashpoint solvents to clean the carburetor.

CAUTIONDo not use compressed air on an assembled carbu-retor, or the float may be crushed by the pressure.Remove asmany rubber or plastic parts as possiblefrom the carburetor before cleaning the carburetorwith a cleaning solution. This will prevent to dam-age or deterioration of the parts.The carburetor body has plastic parts that cannotbe removed. Do not use a strong carburetor clean-ing solution which could attack these parts instead,use a mild high-flash point cleaning solution safefor plastic parts.Do not use wire or any other hard instrument toclean carburetor parts, especially jets, as they maybe damaged.

•Disassemble the carburetor (see Carburetor Disassem-bly/Assembly).• Immerse all the carburetor metal parts in a carburetorcleaning solution and clean them.•Rinse the parts in water and dry them with compressedair.• Do not use rags or paper to dry parts. Lint may plug thehole or passages.• Blow air through the holes and fuel passages with thecompressed air. All holes must be open.• Assemble the carburetor (see Carburetor Disassem-bly/Assembly).


Carburetor InspectionWARNING

Gasoline is extremely flammable and can be explo-sive under certain. Turn the engine switch stopposition. Do not smoke. Make sure the area iswell ventilated and free from any source of flame orsparks this includes any appliance with a pilot light.

• Inspect the carburetor body for damage. Flange sealingsurfaces should be smooth and free of burrs and nicks.Replace the gasket with a new one if necessary.• Turn the throttle shaft to check that the throttle butterflyvalve move smoothly.If the valve do not move smoothly, replace the carburetorbody and/or throttle shaft.• Check the gasket on the carburetor body.If the gasket condition is not good, replace it with a newone.•Check the other parts of the carburetor for wear or dam-age. Replace the part with a new one if necessary.•Clean and check the float level as follows.

CAUTIONDo not push down on the float during float levelchecking.

•With the float [A] assembly installed onto the carburetorbody, hold the carburetor upside down at eye level. Gen-tly support the float with a finger and bring it down slowlyso that the float arm tab [B] touches the float valve [C]. Thefloat lower surface [D] should be parallel with the carbu-retor body mating surfaces.If the float position is not correct, replace the float with anew one.

• For Priming model; the float assembly is as shown in thefigure.


• Inspect the float valve for excessive wear or damage. Thetip should be smooth, without any grooves, scratches, ortears. The rod at the other end of the needle should movesmoothly when pushed in and released.Good [A]Bad [B]If either the needle or the seat is worn or damaged, re-place the float assembly and carburetor body as a set.

FUEL SYSTEM 3-21Priming Pump

Priming Pump Removal•Remove the tube [A] from the priming pump.•Remove the screw [B].• Remove the priming pump from the inlet manifold.• Inspect the priming pump for damages.If the priming pump is damaged, replace it with a new one.

Priming Pump Installation• Install the priming pump in the inlet manifold.• Tighten the screw [A].Torque - Priming Screw: 1.2 N·m (0.12 kgf·m, 11 in·lb)

• Install the tube [B] on the priming pump.

3-22 FUEL SYSTEMInlet Manifold (Choke Start Model)

Inlet Manifold Removal•Unscrew the inlet manifold mounting bolts [A].• Remove the breather pipe [B] from the inlet manifold.

Inlet Manifold Installation•Clean the mating surface of the carburetor and the inletmanifold.• Install the new gasket [A] and the inlet manifold.

• Tighten the inlet manifold mounting nut [A].• There should be no clearance between the inlet manifoldand the fuel tank.

FUEL SYSTEM 3-23Inlet Manifold (Priming Start Model)

Inlet Manifold Removal•Unscrew the inlet manifold mounting bolts [A].• Remove the breather pipe [B] from the inlet manifold.

Inlet Manifold Installation•Replace the O-ring [A] with a new one.•Clean the mating surface of the carburetor and the inletmanifold.

• Install the new gasket [A] and the inlet manifold.

• Tighten the inlet manifold mounting bolts [A].• There should be no clearance between the inlet manifoldand the fuel tank.

3-24 FUEL SYSTEMInlet Manifold

Inlet Manifold Inspection• Inspect the inlet manifold for cracks.•Cracks not visible to the eye may be detected by using ametal crack detection system (Visual color check: com-monly found at automotive parts store).If a crack is present in the inlet manifold, replace it with anew one.• Inspect the gasket surfaces for burrs and nicks.

FUEL SYSTEM 3-25Fuel Tank

Fuel Tank Removal•Place a suitable container beneath the fuel hose.• Loosen the clamp and remove the fuel hose from the car-buretor.• Loosen the clamp and remove the fuel hose [A] from thetank drain.•Remove the fuel tank bracket bolts [B].• Remove the fuel tank [C].

Fuel Tank Installation• Install the fuel tank.•When installing the fuel tank, there should be no clear-ance between the inlet manifold and the fuel tank.

• Install the fuel hose [A] on the fuel tank [B].• Install the fuel hose on the carburetor.• Tighten the fuel tank bracket bolts [C].Torque - Fuel Tank Bracket Bolts: 6.9 N·m (0.70 kgf·m, 61

in·lb)

• Install the removed parts (see appropriate chapters).

Fuel Tank CleaningWARNING

Clean the fuel tank in a well ventilated area, and takecare that there is no sparks or flame anywhere nearthe working area. Because of the danger of highlyflammable liquids, do not use gasoline or low-flashpoint solvent to clean the tank.

•Remove the fuel tank (see Fuel Tank Removal).• Pour the solvent out of the tank.• Pour some high-flash point solvent into the fuel tank andshake the tank to remove dirt and fuel deposits.• Dry the fuel tank with compressed air.• Install the fuel tank (see Fuel Tank Installation).

3-26 FUEL SYSTEMFuel Filter

Fuel Filter Inspection•Refer to the Fuel Filter Inspection in the Peri-odic Maintenance chapter.

FUEL SYSTEM 3-27Air Cleaner

Air Cleaner Element Removal•Refer to the Air Cleaner Element Removal in the PeriodicMaintenance chapter.

Air Cleaner Element Installation•Refer to the Air Cleaner Element Installation in the Peri-odic Maintenance chapter.

Air Cleaner Element Cleaning and Inspection•Refer to the Air Cleaner Element Cleaning and Inspectionin the Periodic Maintenance chapter.

Air Cleaner Body Removal (Priming Model)•Remove the nut [A].•Move the direction of the arrow [C] and remove the aircleaner case [B].• Remove:Paper ElementFoam Element

Air Cleaner Body Installation• Install:Foam ElementPaper Element• Install the projection [B] of the air cleaner case [A] to fitthe hollow [C] of the air cleaner body.

• Tighten the nut [A].

Air Cleaner Body Removal (Choke Model)•Turn the air cleaner case [A] in the direction of the arrow[B] and remove the air cleaner case [A].

3-28 FUEL SYSTEMAir Cleaner

Air Cleaner Body Installation• Install the projection [B] of the air cleaner case [A] to fitthe hollow [C] of the air cleaner body.

• Turn the air cleaner case [A] in the direction of the arrow[B].

Air Cleaner Housing (Case and Body) Inspection•Refer to the Air Cleaner Housing (Case and Body) Inspec-tion in the Periodic Maintenance chapter.

COOLING SYSTEM 4-1

4

Cooling SystemTable of Contents

Exploded View........................................................................................................................ 4-2Cooling Fan ............................................................................................................................ 4-4

Cooling Fan Removal ....................................................................................................... 4-4Cooling Fan Installation .................................................................................................... 4-4Cooling Fan Inspection ..................................................................................................... 4-4

4-2 COOLING SYSTEMExploded View

COOLING SYSTEM 4-3Exploded View

TorqueNo. Fastener


1 Flywheel Bolt 42 4.3 312. KAI Model

4-4 COOLING SYSTEMCooling Fan

Cooling Fan Removal•Refer to the Flywheel Removal in the Electrical Systemchapter.

Cooling Fan Installation•Refer to the Flywheel Installation in the Electrical Systemchapter.

Cooling Fan Inspection•Visually inspect the blades [A] in the cooling fan [B].If they are any cracks, warps or damage, replace the cool-ing fan.If any mud or dust have stuck to the cooling fan, clean it.• Clean the cooling fan by washing in detergent and water.

CAUTIONDo not clean the cooling fan in oil solvent. It maybe damage by oil solvent.

ENGINE TOP END 5-1

5

Engine Top EndTable of Contents

Exploded View........................................................................................................................ 5-2Specifications ......................................................................................................................... 5-4Special Tools .......................................................................................................................... 5-6Cylinder Head......................................................................................................................... 5-7

Compression Measurement.............................................................................................. 5-7Cylinder Head Assembly Removal ................................................................................... 5-8Cylinder Head Assembly Installation ................................................................................ 5-8Push Rod Removal ........................................................................................................... 5-9Push Rod Installation ........................................................................................................ 5-9Push Rod Inspection......................................................................................................... 5-10Valve Mechanism Removal/Installation ............................................................................ 5-10Cleaning and Inspection ................................................................................................... 5-11Rocker Arm Inspection...................................................................................................... 5-11

Valves ..................................................................................................................................... 5-12Valve Clearance Inspection .............................................................................................. 5-12Valve Clearance Adjustment............................................................................................. 5-12Valve Seat Inspection ....................................................................................................... 5-12Valve Seat Repair ............................................................................................................. 5-12Valve Head Thickness ...................................................................................................... 5-12Valve Stem Runout ........................................................................................................... 5-12Valve Stem Diameter ........................................................................................................ 5-12Valve Guide Inside Diameter ............................................................................................ 5-13Valve Spring Inspection .................................................................................................... 5-13Automatic Compression Release (ACR) Device Inspection ............................................. 5-13

Cylinder, Piston....................................................................................................................... 5-14Piston Removal................................................................................................................. 5-14Piston Installation.............................................................................................................. 5-15Piston Cleaning................................................................................................................. 5-17Piston Ring and Ring Groove Wear.................................................................................. 5-17Piston Ring End Gap ........................................................................................................ 5-18Piston Pin, Piston Pin Hole, and Connecting Rod Wear................................................... 5-18Piston Diameter ................................................................................................................ 5-19Cylinder Inside Diameter................................................................................................... 5-19

Muffler .................................................................................................................................... 5-20Muffler Removal................................................................................................................ 5-20Muffler Installation............................................................................................................. 5-20Inspection.......................................................................................................................... 5-20

5-2 ENGINE TOP ENDExploded View

ENGINE TOP END 5-3Exploded View

TorqueNo. Fastener


1 Cylinder Head Bolts (7T) 22 2.2 16 SCylinder Head Bolts (7N) 25 2.5 18 SCylinder Head Bolts (9N) 26 2.6 19 S

2 Valve Clearance Lock Screws 6.9 0.70 61 in·lb3 Connecting Rod Big End Cap Bolts 5.9 0.60 52 in·lb O4 Rocker Arm Bolts 28 2.8 205 Spark Plug 22 2.2 166 Rocker Cover Mounting Bolts 5.9 0.60 52 in·lb7 Muffler Cover Bolt 6.9 0.70 61 in·lb8. KAI ModelO: Apply engine oil.R: Replacement PartsS: Follow the specified tightening sequence.

5-4 ENGINE TOP ENDSpecifications

Item Service LimitCylinder HeadCylinder Compression 196 kPa (2.0 kgf/cm², 28.4 psi) (MIN)Cylinder Head Warp 0.03 mm (0.001 in.)

ValvesValve Head Thickness:Exhaust 0.36 mm (0.014 in.)Inlet 0.35 mm (0.014 in.)

Valve Stem Runout:Exhaust 0.05 mm (0.002 in.)Inlet 0.05 mm (0.002 in.)

Valve Stem Diameter:Exhaust 5.93 mm (0.233 in.)Inlet 5.93 mm (0.233 in.)

Valve Guide Inside Diameter:Exhaust 6.08 mm (0.239 in.)Inlet 6.08 mm (0.239 in.)

Valve Spring Free Length:Exhaust 33.5 mm (1.32 in.)Inlet 33.5 mm (1.32 in.)

Rocker Arm Push Rod Runout:Exhaust 0.5 mm (0.02 in.)Inlet 0.5 mm (0.02 in.)

Cylinder, PistonPiston Diameter 64.79 mm (2.551 in.)Piston Ring/Groove Clearance:Top 0.17 mm (0.007 in.)Second 0.17 mm (0.007 in.)

Piston Ring Thickness:Top 1.40 mm (0.055 in.)Second 1.40 mm (0.055 in.)

Piston Ring End Gap:Top 0.75 mm (0.029 in.)Second 0.75 mm (0.029 in.)Oil 1.05 mm (0.041 in.)

Piston Pin Outside Diameter 15.96 mm (0.628 in.)Piston Pin Hole Inside Diameter 16.08 mm (0.633 in.)Connecting Rod Small End Inside Diameter 16.06 mm (0.632 in.)Cylinder Inside Diameter 65.10 mm (2.563 in.)Cylinder Bore Out Round 0.056 mm (0.0022 in.)

ENGINE TOP END 5-5Specifications

Item StandardValvesValve Clearance:Exhaust 0.10 ∼ 0.15 mm (0.004 ∼ 0.006 in.)Inlet 0.10 ∼ 0.15 mm (0.004 ∼ 0.006 in.)

Valve Seating Surface Angle:Exhaust 45°Inlet 45°

Valve Seating Surface Width:Exhaust 0.6 ∼ 0.9 mm (0.024 ∼ 0.035 in.)Inlet 0.6 ∼ 0.9 mm (0.024 ∼ 0.035 in.)

Valve Guide Inside Diameter:Exhaust 6.00 ∼ 6.012 mm (0.2362 ∼ 0.2367 in.)Inlet 6.00 ∼ 6.012 mm (0.2362 ∼ 0.2367 in.)

Exhaust Valve Lift Height by ACR 0.9 mm (0.04 in.)Cylinder, PistonCylinder Inside Diameter 64.98 ∼ 65.00 mm (2.558 ∼ 2.559 in.)

5-6 ENGINE TOP ENDSpecial Tools

Compression Gauge:57001-221

Piston Ring Compression:57001-1095

Piston Ring Compression Belt, 55 ∼ 67:57001-1096

Compression Gauge Adapter M14 × 1.25:57001-1159

ENGINE TOP END 5-7Cylinder Head

Compression Measurement•Before measuring compression, do the following.Thoroughly warm up the engine so that engine oil be-tween the piston and cylinder wall will help seal compres-sion as it does during normal running.Stop the engine.•Disconnect the spark plug cap and remove the spark plug.• Attach the compression gauge assembly firmly into sparkplug hole.Special Tools - Compression Gauge [A]: 57001-221

Compression Gauge Adapter [B]: 57001-1159

•Ground the spark plug to the engine.WARNING

To avoid fire, do not ground the spark plug in prox-imity to the plug hole. Keep the plug as far away aspossible from the plug hole.

•Opening the throttle fully, run the engine by pulling the re-coil starter grip several times until the compression gaugestops rising. Read the highest compression value.

Cylinder CompressionService Limit: 196 kPa (2.0 kgf/cm², 28.4 psi) (MIN)

If the compression is higher than the specified value, thepiston rings, cylinder and valves are probably in good con-dition.If the compression is too high, check the following.

1. Carbon build-up on the piston crown and cylinder head- clean off any carbon on the piston crown and cylinderhead.

2. Cylinder head gasket - use only the proper gasket. Theuse of a gasket of incorrect thickness will change thecompression.

3. Valve guides and piston rings - rapid carbon accumula-tion in the combustion chamber may be caused by wornvalve guides or worn piston oil ring. This may be indi-cated by white exhaust smoke.

4. Malfunction of ACR (Automatic Compression Release)with the camshaft.If the cylinder compression is lower than the (MIN), checkthe following.

1. Gas leakage around the cylinder head - replace thedamaged gasket with a new one and check and checkthe cylinder head warp.

2. Condition of the valve seating.3. Valve clearance.4. Piston/cylinder wear, piston seizure.5. Piston ring, piston ring groove.

5-8 ENGINE TOP ENDCylinder Head

Cylinder Head Assembly Removal•Remove:Air Cleaner Elements (see Air Cleaner Element in theFuel System chapter)Recoil Starter (see Recoil Starter Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal in the Fuel Systemchapter)Muffler (see Muffler Removal)Fan Housing (see Flywheel Removal in the ElectricalSystem chapter)Inlet Manifold and Carburetor (see Inlet Manifold Re-moval, Carburetor Removal in the Fuel System chapter)Spark Plug (see Spark Plug Removal in the ElectricalSystem chapter)

• Loosen the rocker cover mounting bolts [A] and removethe cover [B] and the gasket.•When removing the cylinder head, set the piston at theTDC of the compression stroke end.

• Loosen the cylinder head bolts 1/4 turn in the sequenceas shown in the figure.

CAUTIONIf the above procedure is not followed, the cylinderhead may be warped during removal.

•Repeat the sequence until all bolts are removed and liftoff the cylinder head assembly.

NOTEMark the push rods so they can be installed in their orig-inal position during assembly.

Cylinder Head Assembly Installation•Clean the mating surfaces of the cylinder head and thecylinder.• Install the push rods in their original positions on the cylin-der (see Push Rod Installation).• Install the dowel pins.• Set the piston at the TDC of the compression stroke end.• Put new gasket and the cylinder head assembly on thecylinder, then align the push rods under the rocker arms.


•Tighten the cylinder head bolts following the tighteningsequence as shown in the figure.Torque - Cylinder Head Bolts:

7T: 22 N·m (2.2 kgf·m, 16 ft·lb)7N: 25 N·m (2.5 kgf·m, 18 ft·lb)9N: 26 N·m (2.6 kgf·m, 19 ft·lb)

CAUTIONA torque wrench must be used to assure propertorque. Improper tightening of the head bolts mayresult in warping of the cylinder head.

•Check and adjust the valve clearance (see Valve Clear-ance Inspection, Valve Clearance Adjustment in the Peri-odic Maintenance chapter).• Install the gasket and the rocker cover.Torque - Rocker Cover Mounting Bolts: 5.9 N·m (0.60

kgf·m, 52 in·lb)

• Install the removed parts (see appropriate chapters).Push Rod Removal•Set the piston at the TDC of the compression stroke end.•Remove the rocker cover (see Cylinder Head AssemblyRemoval).• Loosen the valve clearance adjusting nuts [A].•Move the rocker arms [B] to clear the push rod upperends.• Pull out the push rods.

NOTEMark the push rods so they can be installed in their orig-inal positions during assembly.

Push Rod Installation•Set the piston at the TDC of the compression stroke end.• Install the push rods [A] in their original positions on thecylinder.To install the push rod in the correct position on the tappet[B], insert the push rod, so the end of the push rod issliding down along the inside wall [C] of the crankcaseand position the push rod end onto the tappet.• Check that both inlet and exhaust push rod on cylinderis at lowest position on the cam lobes [D], if not, turn theflywheel clockwise one turn (360°) and reset at the TDCof the compression stroke end.• Be sure to seat the end of the push rods correctly on thetappets.• Tighten the valve clearance adjusting nuts (see ValveClearance Adjustment in the Periodic Maintenance chap-ter).• Check and adjust the valve clearance (see Valve Clear-ance Inspection, Valve Clearance Adjustment in the Peri-odic Maintenance chapter).

5-10 ENGINE TOP ENDCylinder Head

Push Rod Inspection•Place the push rod in V blocks that are as far apart aspossible, and set a dial gauge [A] on the rod at the halfwaypoint between the blocks. Turn the rod to measure therunout. The difference between highest and the lowestdial readings is the amount of runout.If the runout exceeds the service limit, replace the rod witha new one.

Rocker Arm Push Rod RunoutService Limit: 0.5 mm (0.02 in.)

Valve Mechanism Removal/Installation•Remove the cylinder head assembly (see Cylinder HeadAssembly Removal).

NOTEWhen removing the valvemechanism parts, record theirposition so that they may be reinstalled in their originalposition during assembly.

•Remove:Valve Clearance Adjusting Nuts [A]Rocker Arms [B]

• Support the valve head in the combustion chamber witha suitable block.• To remove the collets [B], push down the valve retainer[A] with thumbs and remove the collets.• Remove the spring [C] and valve [D] .

NOTEValve guide [A] is not replaceable, do not remove it.


•Apply engine oil to the valve stem.• Install the valve.•Check to see that the valve moves smoothly up and downin the guide.• Install the spring and the valve retainer.• To install the collets, push down the valve retainer withthumbs and install the collets.Soak the valve clearance adjusting nuts and rocker armsin the engine oil.• Install the rocker arms by the valve clearance adjustingnuts.• Adjust the valve clearance (see Valve Clearance Adjust-ment in the Periodic Maintenance chapter).

Cleaning and Inspection•Refer to the Cylinder Head Cleaning and Inspection in thePeriodic Maintenance chapter.

Rocker Arm Inspection•Clean and inspect the rocker arm where it touches thepush rod and the valve stem.If the contact points [A] are worn or damaged, replace therocker arm with a new one.

5-12 ENGINE TOP ENDValves

Valve Clearance Inspection•Refer to the Valve Clearance Inspection in the PeriodicMaintenance chapter.

Valve Clearance Adjustment•Refer to the Valve Clearance Adjustment in the PeriodicMaintenance chapter.

Valve Seat Inspection•Refer to the Valve Seat Inspection in the Periodic Mainte-nance chapter.

Valve Seat Repair•Refer to the Valve Seat Repair in the Periodic Mainte-nance chapter.

Valve Head Thickness•Remove the valve (see ValveMechanismRemoval/Instal-lation).•Measure the thickness of the valve head.If the valve head thickness (valve margin) [A] is less thanthe service limit, replace the valve with a new one.

Valve Head ThicknessService Limit:Exhaust 0.36 mm (0.014 in.)Inlet 0.35 mm (0.014 in.)

Valve Stem Runout•Support the valve on V blocks at each end of the stem.•Position a dial gauge perpendicular to the stem.• Turn the valve and read the value variation on the dialgauge.If the stem runout is greater than service limit, replace thevalve with a new one.

Valve Stem RunoutService Limit:Exhaust 0.05 mm (0.002 in.)Inlet 0.05 mm (0.002 in.)

Valve Stem Diameter•Measure the diameter of the valve stem [A] in two di-rections at right angles, at four different positions on thestem.If any single measurement is less than the service limit,replace the valve with a new one.

Valve Stem DiameterService Limit:Exhaust 5.93 mm (0.233 in.)Inlet 5.93 mm (0.233 in.)

ENGINE TOP END 5-13Valves

Valve Guide Inside Diameter•Use a small bore gauge or a micrometer to measure theinside diameter [A] of the valve guides [B] at three posi-tions down the guide length.If the measurement is more than the service limit, replacethe cylinder head with a new one.

Valve Guide Inside DiameterService Limit:Exhaust 6.08 mm (0.239 in.)Inlet 6.08 mm (0.239 in.)

Valve Spring Inspection• Inspect the valve spring for pitting, cracks, rusting, andburns. Replace the spring with a new one if necessary.•Measure the free length [A] of the spring.If the measurement is less than the service limit, replacethe spring with a new one.

Valve Spring Free LengthService Limit:Exhaust 33.5 mm (1.32 in.)Inlet 33.5 mm (1.32 in.)

Automatic Compression Release (ACR) DeviceInspectionThe ACR reduces the compression of the cylinder in or-

der to facilitate the revolution of the crankshaft during theengine starting.•Remove:Rocker Cover (see Cylinder Head Assembly Removal)Spark Plug (see Spark Plug Removal in the ElectricalSystem chapter)•Check if the valves have the specified clearance (seeValve Clearance Inspection in the Periodic Maintenancechapter).• Slowly turn the crankshaft counterclockwise facing thePTO side and observe themovement of the exhaust valve[A] and the rocker arm [B].Immediately after the inlet valve has closed, the rockerarm should push and open the exhaust valve to attaina lift. If the exhaust valve does not lift to the standardheight, the ACR on the camshaft is faulty (see CamshaftInspection in the Camshaft/Crankshaft chapter).

Exhaust Valve Lift Height by ACRStandard: 0.9 mm (0.04 in.)

5-14 ENGINE TOP ENDCylinder, Piston

Piston Removal•Remove:Air Cleaner Elements (see Air Cleaner Element in theFuel System chapter)Recoil Starter (see Recoil Starter Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal in the Fuel Systemchapter)Flywheel (see Flywheel Removal in the Electrical Sys-tem chapter)

•Remove the crankcase cover (see Crankcase Cover Re-moval in the Camshaft/Crankshaft chapter).• Remove the camshaft (see Camshaft Removal in theCamshaft/Crankshaft chapter).• Turn the crankshaft to expose the connecting rod capbolts [A].• Remove the cap bolts and take off the connecting rod cap[B].

NOTERecord the position of the connecting rod cap for rein-stalling the cap.

•Push the connecting rod end into the cylinder, and pull thepiston and the connecting rod out of the cylinder.

• Remove one of the piston pin snap rings [A] with needlenose pliers [B].

• Remove the piston by pushing the piston pin [A].

ENGINE TOP END 5-15Cylinder, Piston

•Carefully spread the ring opening with your thumbs thenpush up to the opposite side of the ring [A] to remove it.• Remove the 3-piece oil ring with your thumbs in the samemanner.

Piston Installation• Install the expander [A] in the piston oil ring groove sothat the expander ends [B] touch together, never overlapthem.• Install the upper and lower steel rails. There is no UP orDown to the rails. They can be installed either way.

•Do not mix up the top and second ring.• Install the second ring so that the flat side comes up.• Install the top ring.• The rings should turn freely in the grooves.Under Cut Style Structure [A]Piston Head [B]Top Ring [C]Second Ring [D]

• Align the piston and rings with the piston ring end gap asshown in the figure.Arrow Match Mark [A]Top Ring End Gap, Upper Steel Rail End Gap [B]45° [C]Second Ring End Gap, Lower Steel Rail End Gap [D]

• Apply engine oil to the piston pin.• Assemble the piston onto the connecting rod as follows:Align the arrow mark [A] on the piston crown as shownin the figure, then insert the piston pin into the piston pinhole.


• Install the snap ring [A] in the piston [B] as shown in thefigure.

CAUTIONDo not reuse the snap rings, as removal weakensand deforms them. They could fall out and scorethe cylinder wall.

•Apply engine oil to the piston skirt and the cylinder bore.Using the piston ring compressor grip [A] and the belt [B],lightly tap the top of the piston with a plastic mallet [C] toinsert the piston and the connecting rod into the cylinder.Special Tools - Piston Ring Compressor Grip: 57001-1095

Piston Ring Compressor Belt: 57001-1096

• Insert the piston and the connecting rod so that the arrowmark [A] on the piston crown faces the flywheel side [B].

CAUTIONThe connecting rod and the connecting rod big endcap are machined at the factory in the assembledstate, so they must be replaced together as a set.

•Apply engine oil to the inner surface [A] of the connectingrod big end [B] and cap [C].• Set the rod and the cap aligning the mark [D] of the rod tothe mark of cap, install the connecting rod big end cap intheir original position on the connecting rod big end.• Apply a small amount of engine oil to the cap bolts [E].• Tighten the cap bolts.Torque - Connecting Rod Big End Cap Bolts: 5.9 N·m (0.60

kgf·m, 52 in·lb)

• Install:Camshaft (see Camshaft Installation in theCamshaft/Crankshaft chapter)Crankcase Cover (see Crankcase Cover Installation inthe Camshaft/Crankshaft chapter)• Install the removed parts (see appropriate chapters).


Piston Cleaning•Remove the piston and piston rings (see Piston Re-moval).

CAUTIONNever clean the piston head assembled. Carbonparticles will fall between the piston and cylinder,and damage the piston and cylinder.

•Scrape the carbon off [A] the piston head.•Use scraping tools carefully. Do not gouge the pistonhead. To avoid gouging, use scrapers that material willnot damage the piston head.•Clean the piston ring grooves [A] with a broken piston ringor other suitable tools.

CAUTIONBe careful not to widen the ring grooves. Damagedring grooves will require piston replacement.

Piston Ring and Ring Groove Wear•Clean the piston (see Piston Cleaning).• Visually inspect the piston rings and ring grooves.If the piston rings are worn unevenly or damaged, replacethem with new ones.If the ring grooves are worn unevenly or damaged, re-place both the piston and piston rings with new ones.•Measure the clearance between the top and the secondrings and their grooves using a thickness gauge [A].If the piston ring/groove clearance is greater than the ser-vice limit, replace the piston with a new one.

Piston Ring/Groove ClearanceService Limit:Top 0.17 mm (0.007 in.)Second 0.17 mm (0.007 in.)

NOTEThe oil ring is a three piece assembled ring. It is difficultto measure the ring groove clearance and thickness.Visually inspect the oil ring, the ring groove clearanceand the thickness.


•Measure the piston ring thickness [A].Use amicrometer tomeasure the ring thickness at severalpoints around the rings.If any of the measurement is less than the service limit,replace the entire set of rings with new ones.

Piston Ring ThicknessService Limit:Top 1.40 mm (0.055 in.)Second 1.40 mm (0.055 in.)

NOTEWhen using new rings in a used piston, check if thegroove wear is even. The rings should fit perfectly par-allel to the groove sides. If not, replace the piston witha new one.

Piston Ring End Gap•Remove the piston rings.• Push each ring (one at a time) in the cylinder bore to apoint close to the bottom of the cylinder bore.Use the piston to push it in to be sure it is square.•Measure the gap [A] between the ends of the ring [B] witha thickness gauge.If the end gap of any ring is greater than the service limit,replace the entire set of rings with new ones.

Piston Ring End GapService Limit:Top 0.75 mm (0.029 in.)Second 0.75 mm (0.029 in.)Oil 1.05 mm (0.041 in.)

Piston Pin, Piston Pin Hole, and Connecting RodWear•Remove the piston pin.•Measure the piston pin diameter with amicrometer at sev-eral points.If the outside diameter is less than service limit, replacethe piston pin with a new one.

Piston Pin Outside DiameterService Limit: 15.96 mm (0.628 in.)

•Measure the inside diameter [A] of the piston pin hole atseveral points on both side. Use a dial bore gauge.If the inside diameter is greater than the service limit, re-place the piston with a new one.

Piston Pin Hole Inside DiameterService Limit: 16.08 mm (0.633 in.)


•Measure the inside diameter [A] of the connecting rodsmall end at several points. Use a dial bore gauge.If the inside diameter is greater than the service limit, re-place the connecting rod with a new one.

Connecting Rod Small End Inside DiameterService Limit: 16.06 mm (0.632 in.)

Piston Diameter•Measure the outside diameter [A] of the piston 12.5 mm(0.9 in.) up [B] from the bottom of the piston at a rightangle to the direction of the piston pin hole.If the measured outside diameter is less than the servicelimit, replace the piston with a new one.

Piston DiameterService Limit: 64.79 mm (2.551 in.)

Cylinder Inside Diameter•Clean and measure the cylinder inside diameter.Use a dial bore gauge to measure front-to-back and side-to-side at the points as shown in the figure.If any of the cylinder bore measurements is greater thanthe service limit, replace the cylinder with a new one.10 mm (0.39 in.) [A]Middle [B]

Cylinder Inside DiameterStandard: 64.98 ∼ 65.00 mm (2.558 ∼ 2.559 in.)Service Limit: 65.10 mm (2.563 in.)

Cylinder Bore Out RoundService Limit: 0.056 mm (0.0022 in.)

5-20 ENGINE TOP ENDMuffler

Muffler Removal•Remove:Muffler Cover Bolt [C]Muffler Cover Nuts [A]Muffler Cover [B]Muffler•Remove the gasket.• Do not use unnecessary force on the muffler when remov-ing the muffler assembly, or they could become damagedor distorted.

Muffler Installation•Clean the gasket surface and install a new gasket eachtime of the muffler installation.• Install the muffler.• Install the muffler cover.• Tighten the muffler cover nuts and bolt.Torque - Muffler Cover Bolt: 6.9 N·m (0.70 kgf·m, 61 in·lb)

•After installation, thoroughly warm up the engine, wait un-til the engine cools down and retighten the nuts and bolt.

Inspection• Inspect the muffler for dents, cracks, rust and holes.If the muffler is damaged, replace the muffler with a newone for best performance and minimum noise.•Check the muffler for distortion or loose internal compo-nents. Loose internal muffler components may result inthe exhaust flow restriction and the engine output de-crease.

LUBRICATION SYSTEM 6-1

6

Lubrication SystemTable of Contents

Exploded View........................................................................................................................ 6-2Engine Oil Flow Chart............................................................................................................. 6-4Specifications ......................................................................................................................... 6-5Engine Oil .............................................................................................................................. 6-6

Oil Level Inspection........................................................................................................... 6-6Oil Change........................................................................................................................ 6-6

Lubrication System................................................................................................................. 6-7Oil Pump................................................................................................................................. 6-8

Oil Pump Removal ............................................................................................................ 6-8Oil Pump Installation ......................................................................................................... 6-8Oil Pump Inspection.......................................................................................................... 6-8

6-2 LUBRICATION SYSTEMExploded View

LUBRICATION SYSTEM 6-3Exploded View

TorqueNo. Fastener


1 Oil Drain Plug 22 2.2 162 Oil Filter Cover Bolt 6.9 0.70 61 in·lb3. Without Oil Filter Model4. With Oil Filter ModelO: Apply engine oil.R: Replacement Parts

6-4 LUBRICATION SYSTEMEngine Oil Flow Chart

LUBRICATION SYSTEM 6-5Specifications

Item StandardEngine OilType SF, SG, SH or SJ classViscosity SAE30, SAE10W-30Capacity 0.65 L (0.69 US qt)Level Operating range (grid area) on dipstick

Item Service LimitOil PumpInner and Outer Rotor Clearance 0.14 mm (0.006 in.)Outer Rotor Outside Diameter 22.940 mm (0.9031 in.)Outer Rotor Thickness 11.960 mm (0.4709 in.)Pump Housing Inside Diameter 23.241 mm (0.915 in.)Pump Housing Depth 12.220 mm (0.4811 in.)

6-6 LUBRICATION SYSTEMEngine Oil

CAUTIONEngine operation with insufficient, deteriorated,or contaminated engine oil will cause acceleratedwear andmay result in engine seizure and accident.Before starting the engine for the first time, add oil:The engine is shipped dry. Preoil the engine to forceall air from the internal oil passages.

•Fill fresh engine oil to the specified level (see Oil Changein the Periodic Maintenance chapter).• Run the engine at slow speed for 2 minutes.• Stop the engine and check the oil level.Oil Level Inspection•Refer to the Oil Level Inspection in the Periodic Mainte-nance chapter.

Oil Change•Refer to the Oil Change in the Periodic Maintenancechapter.

LUBRICATION SYSTEM 6-7Lubrication System

The oil pump on the camshaft top discharges the oil.The oil passes the crankcase oil passage, the discharge

hole on the crankcase flywheel side, and the camshaft gearside edge. Finally, the oil mist lubricates the connecting rodbig end, the small end, the crankshaft and other internalcomponents.

6-8 LUBRICATION SYSTEMOil Pump

Oil Pump Removal•Remove:Air Cleaner Elements (see Air Cleaner Element Removalin the Fuel System chapter)Recoil Starter (see Recoil Stater Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal in the Fuel Systemchapter)Flywheel (see Flywheel Removal in the Electrical Sys-tem chapter)Crankcase Cover (see Crankcase Cover Removal in theCamshaft/Crankshaft chapter)Camshaft (see Camshaft, Tappet Removal in theCamshaft/Crankshaft chapter)Connecting Rod (see Connecting Rod Removal in theCamshaft/Crankshaft chapter)Crankshaft (see Crankshaft Removal in theCamshaft/Crankshaft chapter)

•Remove the oil pump assembly [A].

Oil Pump Installation•Fill the rotor housing with engine oil for initial lubrication.• Install the pump assembly [A] in the crankcase.• Install the removed parts (see appropriate chapters).

Oil Pump Inspection•Remove the oil pump (see Oil Pump Removal).• Visually inspect the outer and inner rotor.If there is any damage or uneven wear, replace them withnew ones.Check the clearance [A] between the inner and outer rotorwith a filler gauge. Measure the clearance between thehighest point of the inner rotor and the highest point of theouter rotor.If the measurement exceed the service limit, replace therotors as a set with new ones.

Inner and Outer Rotor ClearanceService Limit: 0.14 mm (0.006 in.)

LUBRICATION SYSTEM 6-9Oil Pump

•Measure the outside diameter [A] of the outer rotor with amicrometer at several points.If the rotor diameter is less than the service limit, replaceboth the inner and outer rotor with new ones.

Outer Rotor Outside DiameterService Limit: 22.940 mm (0.9031 in.)

•Measure the thickness [B] of the outer rotor with a mi-crometer at several pointsIf the rotor thickness is less than the service limit, replaceboth the inner and outer rotor.

Outer Rotor ThicknessService Limit: 11.960 mm (0.4709 in.)

•Measure the inside diameter [A] of the pump housing withan inside micrometer at several points.If the inside diameter is more than the service limit, re-place the crankcase with a new one.

Pump Housing Inside DiameterService Limit: 23.241 mm (0.915 in.)

•Measure the depth [B] of the pump housing with a depthmicrometer at several points.If any of measurement is more than the service limit, re-place the crankcase.

Pump Housing DepthService Limit: 12.220 mm (0.4811 in.)

CAMSHAFT/CRANKSHAFT 7-1

7

Camshaft/CrankshaftTable of Contents

Exploded View........................................................................................................................ 7-2Specifications ......................................................................................................................... 7-4Crankcase .............................................................................................................................. 7-5

Crankcase Cover Removal ............................................................................................... 7-5Crankcase Cover Installation ............................................................................................ 7-5Inspection.......................................................................................................................... 7-6Cleaning............................................................................................................................ 7-7

Breather.................................................................................................................................. 7-8Breather Chamber Cover Removal .................................................................................. 7-9Breather Chamber Cover Installation ............................................................................... 7-9Breather Valve Inspection ................................................................................................. 7-9

Camshaft, Tappet ................................................................................................................... 7-10Camshaft, Tappet Removal............................................................................................... 7-10Camshaft, Tappet Installation............................................................................................ 7-11Camshaft Disassembly ..................................................................................................... 7-11Camshaft Assembly .......................................................................................................... 7-11Camshaft Inspection ......................................................................................................... 7-11Camshaft Bearing/Journal Wear....................................................................................... 7-12

Crankshaft, Connecting Rod .................................................................................................. 7-13Connecting Rod Removal ................................................................................................. 7-13Connecting Rod Installation .............................................................................................. 7-13Crankshaft Removal ......................................................................................................... 7-13Crankshaft Installation ...................................................................................................... 7-13Cleaning/Inspection ......................................................................................................... 7-13Connecting Rod Bend/Twist.............................................................................................. 7-14Connecting Rod Big End/Crankpin Width Wear ............................................................... 7-14Connecting Rod Big End Bearing/Crankpin Wear ............................................................ 7-15Crankshaft Runout ............................................................................................................ 7-15Crankshaft Main Journal/Wear ......................................................................................... 7-16

7-2 CAMSHAFT/CRANKSHAFTExploded View

CAMSHAFT/CRANKSHAFT 7-3Exploded View

TorqueNo. Fastener


1 Crankcase Cover Bolts 8.8 0.90 78 in·lb S2 Crankcase Cover Bolt (Cylinder Side) 5.9 0.60 52 in·lb S3 Connecting Rod Big End Cap Bolts 5.9 0.60 52 in·lb O4 Valve Clearance Lock Screws 6.9 0.70 61 in·lb5 Rocker Arm Bolts 28 2.8 20HG: Apply high-temperature grease.O: Apply engine oil.R: Replacement PartsS: Follow the specified tightening sequence.

7-4 CAMSHAFT/CRANKSHAFTSpecifications

Item Service LimitCamshaft, TappetCam Lobe Height:Exhaust 22.060 mm (0.8685 in.)Inlet 22.060 mm (0.8685 in.)

Camshaft Journal Diameter:PTO Side 7.77 mm (0.3059 in.)Flywheel Side 13.927 mm (0.5483 in.)

Camshaft Hole Inside Diameter:Crankcase Cover 11.060 mm (0.4354 in.)

Crankshaft, Connecting RodConnecting Rod Bend TIR 0.2/100 mm (0.008/3.94 in.)Connecting Rod Twist TIR 0.2/100 mm (0.008/3.94 in.)Connecting Rod Big End Width 23.44 mm (0.92 in.)Crankpin Width 24.17 mm (0.95 in.)Connecting Rod Big End Inside Diameter 31.040 mm (1.222 in.)Crankpin Outside Diameter 30.97 mm (1.219 in.)Crankshaft Runout TIR 0.05 mm (0.002 in.)Crankshaft Journal Diameter:PTO Side 27.96 mm (1.101 in.)Flywheel Side 27.98 mm (1.102 in.)

CrankcasePTO Shaft Hole Inside Diameter:Crankcase Cover 27.98 mm (1.102 in.)

Crankshaft Journal Metal Inside Diameter:Crankcase 27.98 mm (1.102 in.)

CAMSHAFT/CRANKSHAFT 7-5Crankcase

Crankcase Cover Removal•Drain the oil (see Oil Change in the Lubrication Systemchapter).• Remove:Air Cleaner Elements (see Air Cleaner Element Removalin the Fuel System chapter)Recoil Starter (see Recoil Starter Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal in the Fuel Systemchapter)Flywheel (see Flywheel Removal in the Electrical Sys-tem chapter)•Unscrew the mounting bolts [A] and remove thecrankcase cover [B] from the crankcase.

• For KAI model; the crankcase cover is as shown in thefigure.

There are two dowel pins on the crankcase mating sur-face. Using a wooden or plastic mallet, gently tap thecrankcase to loosen the crankcase cover.

Crankcase Cover Installation•Remove the old gasket from the mating surfaces of thecrankcase and cover.•Using compressed air, blow out the oil passage in thecrankcase cover.•With a high-flash point solvent, clean off the mating sur-faces of the crankcase and the cover, and wipe them dry.

WARNINGClean the crankcase and cover in a well ventilatedarea, and take care that there are no sparks or flameanywhere near the working area, this includes anyappliance with a pilot light. Do not use gasoline ora low-flash point solvent to clean parts. A fire orexplosion could result.

7-6 CAMSHAFT/CRANKSHAFTCrankcase

•Be sure to replace any oil seal with a new one.Install the oil seal so that the marks [A] face out.Thoroughly pack high-temperature grease [B] into thespace between the seal lip [C] and the dust lip [D]. Pressin the new oil seal using a press or suitable tools until it isflush with flange surface [E]. Do not damage the seal lips.

•Check to see that the dowel pins [A] are in place on thecrankcase.• Install the gasket on the crankcase.

• Install the crankcase cover and tighten the crankcasecover bolts following the tightening sequence as shownin the figure.Torque - Crankcase Cover Bolts: 8.8 N·m (0.90 kgf·m, 78

in·lb)

Torque - Crankcase Cover Bolt (Cylinder Side): 5.9 N·m(0.60 kgf·m, 52 in·lb)

Do not turn one bolt down completely before the others,as it may cause the crankcase cover to warp.

• For KAI model; the tightening sequence is as shown inthe figure.

Inspection•Measure the inside diameter [A] of the PTO shaft holeon the crankcase cover at several points. Replace thecrankcase cover with a new one if the inside diameter ismore than the service limit.

PTO Shaft Hole Inside DiameterService Limit: 27.98 mm (1.102 in.)

CAMSHAFT/CRANKSHAFT 7-7Crankcase

•Measure the inside diameter [A] of the crankshaft journalmetal on the crankcase at several points. Replace thecrankcase with a new one if the inside diameter is greaterthan the service limit.

Crankshaft Journal Metal Inside DiameterService Limit: 27.98 mm (1.102 in.)

Cleaning•Remove:Camshaft and Tappets (see Camshaft, Tappet Removal)Connecting Rod and Piston (see Piston Removal in theEngine Top End chapter)Crankshaft (see Crankshaft Removal)•Clean up the crankcase and the cover with a high-flashpoint solvent, and blow out any foreign particles that maybe in the pockets inside of the crankcasewith compressedair.

WARNINGClean the crankcase and cover in a well ventilatedarea, and take care that there is no sparks or flameanywhere near the working area. Because of thedanger of highly flammable liquids, do not usegasoline or low-flash point solvents.

7-8 CAMSHAFT/CRANKSHAFTBreather

The function of the breather is to create a negative pressure in the crankcase which prevents oil frombeing forced out of the engine through the piston rings, oil seals or gaskets. Valve controls directionof air flow caused by piston movement so that air flow from inside to outside can pass reed valvebut not from outside to inside. Blow-by gas in crankcase passes through valve and expands in valvechamber. The air passes through expands in breather chamber. Then air passes through maze inbreather chamber and is vented to inlet pipe, through breather pipe.

CAMSHAFT/CRANKSHAFT 7-9Breather

Breather Chamber Cover Removal•Remove the bolts [A] and the breather chamber cover [B].

Breather Chamber Cover Installation• Install a new gasket and the breather chamber cover, andtighten the bolts.

Breather Valve Inspection•Remove the breather valve [A].• Inspect the breather valve for breakage, hair crack or dis-tortion, replace it with a new one if necessary.• Inspect the valve seating surface. The surface should befree of nicks or burrs.• Be sure the drain hole on the breather chamber does notaccumulate with slugs before installing the breather valve.

7-10 CAMSHAFT/CRANKSHAFTCamshaft, Tappet

Camshaft, Tappet Removal•Drain the oil (see Oil Change in the Lubrication Systemchapter).• Remove:Air Cleaner Elements (see Air Cleaner Element Removalin the Fuel System chapter)Recoil Starter (see Recoil Starter Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal in the Fuel Systemchapter)Flywheel (see Flywheel Removal in the Electrical Sys-tem chapter)Crankcase Cover (see Crankcase Cover Removal)Rocker Cover [A]

• Position the piston at the TDC of the compression strokeend.• Push down [A] the spring side of the rocker arm [B] andmove it to clear the push rod [C].• Remove the push rods and mark them so they can beinstalled in their original positions during assembly.

• Place the crankcase with flywheel side toward top side.• Pull the camshaft [A] out of the crankcase.

•Remove the tappets [A] and mark them so they can beinstalled in their original positions during assembly.

CAMSHAFT/CRANKSHAFT 7-11Camshaft, Tappet

Camshaft, Tappet Installation•Apply engine oil to the following.Tappet JournalCamshaft JournalCam Lobe SurfaceCamshaft Gear• Install the tappets in those old positions.• Align the punch marks [A] on the crankshaft gear and onthe camshaft gear.• Install the push rods (see Push Rod Installation in theEngine Top End chapter).• Install the rocker arms on the push rods, and install thevalve clearance adjusting nuts.• Adjust the valve clearance (see Valve Clearance Adjust-ment in the Engine Top End chapter).• Install the gasket and rocker cover.• Install the removed parts (see appropriate chapters).Camshaft Disassembly•Remove the camshaft (see Camshaft, Tappet Removal).• Remove:Spring [A]

Do not remove the ACR (automatic compression release)weight [B].While shaking the camshaft, ACR weight swingssmoothly.

Camshaft Assembly• Install the spring.• Install the camshaft (see Camshaft, Tappet Installation).• After assembling the camshaft, check the following items.Camshaft Inspection•Check the camshaft gear [A] for pitting, fatigue cracks,burrs or an evidence of improper tooth contact.Replace the camshaft with a new one if necessary.•Check the top of the cam lobes [B] for wear, burrs or un-even contact.Replace the camshaft with a new one if necessary.

• Inspect the camshaft tomake sure that its ACR (automaticcompression reduction) function operates smoothly anddoes not have any damage or abnormal wear.If ACR parts are worn, replace the ACR with a new one.When the weight [A] is closed, if the top of the arm [B] islower than the base [C], replace the ACR with a new one.When the weight is pulled entirely outward with your fin-ger, if the top of the arm is higher than the cam base,replace the ACR with a new one.

7-12 CAMSHAFT/CRANKSHAFTCamshaft, Tappet

Camshaft Bearing/Journal Wear•Measure the height [A] of each cam lobe.If the cam height is less than the service limit for eitherlobe, replace the camshaft with a new one.

Cam Lobe HeightService Limit:Exhaust 22.060 mm (0.8685 in.)Inlet 22.060 mm (0.8685 in.)

•Measure both camshaft journals at several points aroundthe journal circumference.If the journal diameter is less than the service limit, re-place the camshaft with a new one.

Camshaft Journal DiameterService Limit:PTO Side 7.77 mm (0.3059 in.)Flywheel Side 13.927 mm (0.5483 in.)

•Measure the inside diameter [A] of the camshaft hole onthe crankcase cover at several points.Replace the crankcase cover with a new one if the insidediameter is more than the service limit.

Camshaft Hole Inside Diameter (Crankcase Cover)Service Limit: 11.060 mm (0.4354 in.)

CAMSHAFT/CRANKSHAFT 7-13Crankshaft, Connecting Rod

Connecting Rod Removal•Remove:Piston (see Piston Removal in the Engine Top End chap-ter)

Connecting Rod Installation• Install:Piston (see Piston Installation in the Engine Top Endchapter)

Crankshaft Removal•Drain the oil (see Oil Change in the Lubrication Systemchapter).• Remove:Air Cleaner Elements (see Air Cleaner Element Removalin the Fuel System chapter)Recoil Starter (see Recoil Starter Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal in the Fuel Systemchapter)Flywheel (see Flywheel Removal in the Electrical Sys-tem chapter)Crankcase Cover (see Crankcase Cover Removal)Camshaft (see Camshaft, Tappet Removal)Connecting Rod (see Connecting Rod Removal)• Pull the crankshaft [A] out of the crankcase. Tap gentlywith a wooden or plastic mallet if necessary to loosen thecrankshaft.

Crankshaft Installation•Clean up the crankshaft and crankcase thoroughly.•Check that the pivot arm for the governor is installed (seeGovernor Shaft Installation in the Fuel System chapter).• Pack some amount of high-temperature grease into theoil seal on the crankcase.• Apply engine oil journal.• Install the crankshaft in the crankcase.Cleaning/Inspection•After removing, clean the connecting rod and crankshaftwith a high-flash point solvent and dry them with com-pressed air.• Inspect the teeth of the crankshaft gear for pitting, fatiguecracks, burrs and evidence of improper tooth contact.Replace the gear with a new one if necessary.• Inspect the crankshaft and connecting rod for wear,scratches, evidence of improper contact or other dam-ages.Replace them with new ones if necessary.

7-14 CAMSHAFT/CRANKSHAFTCrankshaft, Connecting Rod

Connecting Rod Bend/Twist•Measure the connecting rod bend.Select an arbor of the same diameter of the connectingrod big end, and insert the arbor through the connectingrod big end.Select an arbor of the same diameter of the piston pinand at least 100 mm (3.94 in.) long, and insert the arborthrough the connecting rod small end.On a surface plate, set the big end arbor on V blocks [A].With the connecting rod held vertically, use a heightgauge to measure the height difference of the small endarbor above the surface plate. Using a dial gauge [B],measure the height at two different positions and thedistance of the two positions is 100 mm (3.94 in.). Thendetermine the connecting rod bent from the measuredheight differences.If the connecting rod bend exceeds the service limit, re-place the connecting rod with a new one.

Connecting Rod BendService Limit: TIR 0.2/100 mm (0.008/3.94 in.)

•Measure the connecting rod twist.With the big end arbor still on the V blocks [A], hold theconnecting rod horizontally and measure the amount thatthe small end arbor differences. Using a dial gauge [B],measure the height at two different positions and the dis-tance of the two positions is 100 mm (3.94 in.). Thendetermine the connecting rod twist from the measuredheight differences.If connecting rod twist exceeds the service limit, replacethe connecting rod with a new one.

Connecting Rod TwistService Limit: TIR 0.2/100 mm (0.008/3.94 in.)

Connecting Rod Big End/Crankpin Width Wear•Measure the connecting rod big end width [A] with a mi-crometer or dial caliper.If the measurement is less than the service limit, replacethe connecting rod with a new one.

Connecting Rod Big End WidthService Limit: 23.44 mm (0.92 in.)

CAMSHAFT/CRANKSHAFT 7-15Crankshaft, Connecting Rod

•Measure the crankpin width [A] with a dial caliper.If the crankpin width is greater than the service limit, re-place the crankshaft with a new one.

Crankpin WidthService Limit: 24.17 mm (0.95 in.)

Connecting Rod Big End Bearing/Crankpin Wear•Apply a thin layer of oil on the threads of the cap bolts.• Install the cap bolts and tighten the bolts to the speci-fied torque (see Piston Installation in the Engine Top Endchapter).•Measure the big end inside diameter [A] at several pointswith a telescoping gauge or inside micrometer.If the inside diameter is greater than the service limit, re-place the connecting rod with a new one.

Connecting Rod Big End Inside DiameterService Limit: 31.040 mm (1.222 in.)

•Measure the crankpin outside diameter [A].Use a micrometer to measure several points around thecrankpin circumference.If the crankpin diameter is less than the service limit, re-place the crankshaft with a new one.

Crankpin Outside DiameterService Limit: 30.97 mm (1.219 in.)

Crankshaft Runout•Measure the crankshaft runout.Set the crankshaft in a flywheel alignment jig [A] or on Vblocks gauge.Set a dial gauge [B] against both journals.Turn the crankshaft slowly to measure the runout. The dif-ference between the highest and lowest dial gauge read-ings (TIR) is the amount of runout.If the measurement exceeds the service limit, replace thecrankshaft with a new one.

Crankshaft RunoutService Limit: TIR 0.05 mm (0.002 in.)

7-16 CAMSHAFT/CRANKSHAFTCrankshaft, Connecting Rod

Crankshaft Main Journal/Wear•Measure both journals at several points around the jour-nal circumference.If the journal diameter is less than the service limit, re-place the crankshaft with a new one.

Crankshaft Journal DiameterService Limit:PTO Side [A] 27.96 mm (1.101 in.)Flywheel Side [B] 27.98 mm (1.102 in.)

STARTER SYSTEM 8-1

8

Starter SystemTable of Contents

Exploded View........................................................................................................................ 8-2Recoil Starter System............................................................................................................. 8-4

Recoil Starter Removal ..................................................................................................... 8-4Recoil Starter Installation .................................................................................................. 8-4Rope Guide Removal........................................................................................................ 8-4Rope Guide Installation..................................................................................................... 8-5

Pad Brake............................................................................................................................... 8-6Pad Brake Assembly Removal ......................................................................................... 8-6Pad Brake Assembly Installation ...................................................................................... 8-6Brake Switch Removal/Installation.................................................................................... 8-7

8-2 STARTER SYSTEMExploded View

STARTER SYSTEM 8-3Exploded View

TorqueNo. Fastener


1 Recoil Starter Mounting Bolts 6.9 0.70 61 in·lb2 Brake Arm Mounting Bolt 9.3 0.95 82 in·lb3 Brake Lever Assembly Mounting Bolt 6.9 0.70 61 in·lb4. KAI Model

8-4 STARTER SYSTEMRecoil Starter System

Recoil Starter Removal•Remove:Recoil Starter Mounting Bolts [A]Recoil Starter [B]

Recoil Starter Installation• Install the recoil starter and tighten the mounting bolts.Torque - Recoil Starter Mounting Bolts: 6.9 N·m (0.70

kgf·m, 61 in·lb)

Rope Guide Removal•Remove the recoil starter (see Recoil Starter Removal).• Draw the rope from the inside [B] of the guide after pullingthe starter grip [A] 30 cm (1 ft).• Clamp the rope with a clip [D] so it can not wind back ontothe reel [C].• Pry the knot [E] out of the starter grip and untie it.• Remove the starter grip from the rope and remove therope from the guide.

•Connect the rope to the case so it can not wind back ontothe reel.

WARNINGWear gloves to avoid injury for the remaining steps.

•Put a suitable rope or band [B] through the guide [A].• Hold the case securely and pull the band with the guide.

STARTER SYSTEM 8-5Recoil Starter System

Rope Guide Installation•Set the guide so that the thick side [A] faces the outside[B], and press it with a suitable tool [C].

• Clamp the rope with the clip [A] so it can not wind back.•Untie the rope from the case and push it through theguide.• Install a starter grip [B] and secure it with a knot [C].• Hold the starter grip, then remove the clip from the ropeand put back the grip to the case slowly.

8-6 STARTER SYSTEMPad Brake

Pad Brake Assembly Removal•Remove:Air Cleaner Elements (see Air Cleaner Element Removalin the Fuel System chapter)Recoil Starter (see Recoil Starter Removal)Fuel Tank (see Fuel Tank Removal in the Fuel Systemchapter)Pulley (see Flywheel Removal in the Electrical Systemchapter)Fan Housing and Fan (see Flywheel Removal in theElectrical System chapter)

•Remove the brake lever assembly mounting bolt [A].• Remove the spring [B] from the lever assembly and re-move the lever assembly [C].• Remove the spring and bolt [D].

• Remove the ground lead from the ignition coil.• Remove the control panel assembly (see Control PanelAssembly Removal in the Fuel System chapter).• Remove the spring [A] from the brake panel assembly.•Remove the spring.•Remove the brake arm mounting bolt [B] and nut [C].• Remove the brake arm and brake panel.

CAUTIONMake sure that pad brake always stop engine within3 secondswhen pad brake is ON. If not, check brakeshoe and/or related parts for wear and damage. Re-place parts if necessary.

Pad Brake Assembly Installation• Install the brake arm [A], brake panel [B] and spring [C]as shown in the figure.• Install the brake arm mounting bolt and nut.Torque - Brake Arm Mounting Bolt: 9.3 N·m (0.95 kgf·m, 82

in·lb)

• Install the brake panel assembly and control panel as-sembly (see Control Panel Assembly Installation in theFuel System chapter).• Install the ground lead in the ignition coil (see Ignition CoilInstallation in the Electrical System chapter).

STARTER SYSTEM 8-7Pad Brake

•Tighten the bolt [A].• Install the lever assembly [B].• Tighten the brake lever assembly mounting bolt [C].Torque - Brake Lever Assembly Mounting Bolt: 6.9 N·m

(0.70 kgf·m, 61 in·lb)Check the lever assembly moves smoothly after installa-tion.• Install the spring [D].• Install the removed parts (see appropriate chapters).• Adjust the idle speed to the specifications (see Idle SpeedAdjustment in the Periodic Maintenance chapter).

Brake Switch Removal/Installation•Refer to the illustration shown for removal and installation.Nut [A]Washer [B]Earth Lead Wire [C]Cover [D]Brake Panel Assembly [E]Insulator [F]Terminal [G]Kill Switch Bolt [H]Torque - Kill Switch Bolt: 1.5 N·m (0.15 kgf·m, 13 in·lb)

• Install the brake switch [A] as shown in the figure.

ELECTRICAL SYSTEM 9-1

9

Electrical SystemTable of Contents

Exploded View........................................................................................................................ 9-2Specifications ......................................................................................................................... 9-4Special Tools .......................................................................................................................... 9-5Wiring Diagram ...................................................................................................................... 9-6Precautions............................................................................................................................. 9-7Charging System.................................................................................................................... 9-8

Flywheel Removal............................................................................................................. 9-8Flywheel Installation.......................................................................................................... 9-9Circuit Composition........................................................................................................... 9-11Action Principle ................................................................................................................. 9-11Cautions of Handling and Maintenance............................................................................ 9-11Charging Coil Inspection................................................................................................... 9-12

Ignition System....................................................................................................................... 9-13Ignition Coil Removal ........................................................................................................ 9-13Ignition Coil Installation ..................................................................................................... 9-13Ignition Coil Inspection...................................................................................................... 9-14Spark Plug Removal ......................................................................................................... 9-14Spark Plug Installation ...................................................................................................... 9-14Spark Plug Cleaning and Inspection................................................................................. 9-14Spark Plug Gap Inspection ............................................................................................... 9-14

9-2 ELECTRICAL SYSTEMExploded View

ELECTRICAL SYSTEM 9-3Exploded View

TorqueNo. Fastener


1 Flywheel Bolt 42 4.3 312 Spark Plug 22 2.2 163 Kill Switch Bolt 1.5 0.15 13 in·lb4. KAI Model

DO: Degrease the taper.

9-4 ELECTRICAL SYSTEMSpecifications

Item Standard Service LimitIgnition SystemIgnition Coil:Primary Winding Resistance in the text – – –Secondary Winding Resistance in the text – – –

Spark Plug:Type NGK BPR5ES – – –Gap 0.75 mm (0.030 in.) – – –

ELECTRICAL SYSTEM 9-5Special Tools

Hand Tester:57001–1394

Bracket Holder:57001–1536

9-6 ELECTRICAL SYSTEMWiring Diagram

ELECTRICAL SYSTEM 9-7Precautions

There are a number of important precautions that youmust follow when servicing electrical systems. Learn andobserve all the rules below.Do not hit the electric parts with a hammer or do not dropthe electric parts. These may result in the electric partsdamage or breakage.Troubles may involve one or all items in some cases.Never replace a defective part without determining whatCAUSED the failure. If the failure was occurred by an-other item or some other items, repair and/or replace theitem(s). Or the failure may happen again.Make sure all connectors in the circuit are clean and tight,and examine leads for signs of burning, fraying, etc. Poorleads and bad connections will affect electrical systemoperation.Measure the coil and winding resistance when the partsare cold (at room temperature).

Connectors are as shown in the figure.Female Connector [A]Male Connector [B]

9-8 ELECTRICAL SYSTEMCharging System

Flywheel Removal•Remove:Air Cleaner Elements (see Air Cleaner Element Removalin the Fuel System chapter)Recoil Starter (see Recoil Starter Removal in the StarterSystem chapter)Fuel Tank (see Fuel Tank Removal in the Fuel Systemchapter)

•Hold the pulley [B] with bracket holder [A], remove theflywheel bolt and washer.Special Tool - Bracket Holder: 57001-1536

•Remove the pulley.

• Loosen the fan housing bolts [A] and remove the fanhousing [B] and screen [C].• Remove the fan.

• For KAI model; the fan housing bolts are as shown in thefigure.

•Note the following.•Remove:Ignition Coil (see Ignition Coil Removal)•Remove the pad brake assembly (see Pad Brake Assem-bly Removal in the Starter System chapter).

ELECTRICAL SYSTEM 9-9Charging System

•Using a suitable flywheel puller [A], remove the flywheel[B].

CAUTIONAlways use flywheel puller.

•Note the following.•Remove:Woodruff Key [A]

Flywheel Installation•Note the following.•Using a cleaning fluid, clean off any oil or dirt on the fol-lowing portions and dry them with a clean cloth.Crankshaft Tapered Portion [A]Flywheel Tapered Portion [B]

Degrees the flywheel taper, crankshaft taper, before as-sembring.• Fit the Woodruff key [C] securely in the slot in the crank-shaft before installing the flywheel.• Install the flywheel onto the crankshaft taper so that thewoodruff key fits in the key way in the hub of the flywheel.

• Note the following.• Install:Ignition Coil (see Ignition Coil Installation)Pad Brake Assembly (see Pad Brake Assembly Instal-lation in the Starter System chapter)• Install the fan [A] so that two positioning bosses [B] fitaround flywheel ignition magnet [C].• Install the fan housing and tighten the fan housing mount-ing screws.• Install the screen to the fan housing.


• Install the pulley [A] so that the projection [B] fit into therecess [C] of the flywheel.

• Install the pulley [A] and washer [B] as shown in the figure.• Tighten the flywheel bolt [C].Torque - Flywheel Bolt: 42 N·m (4.3 kgf·m, 31 ft·lb)


• For Modified model; note the following.• Install the pulley [A].• Tighten the flywheel bolt [B].Torque - Flywheel Bolt: 42 N·m (4.3 kgf·m, 31 ft·lb)


ELECTRICAL SYSTEM 9-11Charging System

Circuit Composition

C: CondenserCo: Ignition Coil CoreD1: DiodeD2: DiodeD3: Diode

E: Exciter CoilL1: Primary CoilL2: Secondary Coil

SCR: ThyristorSP: Spark Plug

Action Principle(1) Fundamental action1. Genarated positive direction voltage by rotor rotated in the exciter coil (E) flows the electrical cur-rent through the diode (D1), and discharged to the condenser (C).

2. Generated opposite direction current flows to the thyristor (SCR) because voltage had generatedin the exciter coil (E) also at the opposite direction.

3. If the voltage of opposite direction reaches to the trigger voltage of the thyristor (SCR), the thyristor(SCR) will be ON state, and voltage is charged by the condenser (C) and discharged rapidly to theprimary coil (L1).

4. The primary voltage of several hundreds volt generate by large electrical current flows rapidly tothe primary coil (L1), the primary voltage are risen by the secondary coil (L2), and turn into thesecondary voltage of several thousands volt, and spark generate to the spark plug (SP) of outputside.

(2) Spark advance characteristic1. If the revolutions number rises, the opposite direction voltage of exciter coil (E) which the triggerposition of the thyristor (SCR) changes and spark advance because of voltage wave form willchange.

2. Spark advance is controlled by spark advance characteristic control circuit in the figure.(3) Spark delay characteristic1. The trigger position of the thyristor (SCR) changes and spark delay by decreasing the voltage waveform applied to the thyristor (SCR) in the revolutions number set up in the spark delay characteristiccontrol circuit in the figure.

2. The start revolutions number of spark delay is controlled by spark delay characteristic control circuitin the figure.

Cautions of Handling and Maintenance


(1) Do not near the magnet by the heat of fire.(2) Ignition timing is not adjustable because it is fixed.(3) When carry out the spark test, pull the recoil starter

knob with strong force. If the flywheel does not turnedmore than the ignition revolutions, spark does not ig-nite.

Charging Coil Inspection•Remove the ignition coil with charging coil (see IgnitionCoil Removal).•Measure the winding resistance as follows:Set the hand tester to the R × 1 Ω range.Special Tool - Hand Tester: 57001-1394Make the measurements as shown in the table.Charging Coil Winding Resistance

+–

A D

A – 30 ∼ 80 ΩD ∞ –

ELECTRICAL SYSTEM 9-13Ignition System

Ignition Coil Removal•Note the following.•Remove:Fan (see Flywheel Removal)Spark Plug CapGround Lead [A]Bolts [B]Ignition Coil [C]

Ignition Coil Installation•Note the following.• Install ignition coil [A] on crankcase and tighten bolt (1)first, then tighten bolt (2). While tightening bolts, adjustthe air gap [B] between the leg of ignition coil and themagnet to the specified gap value as shown.

Ignition Coil Air GapStandard: 0.2 ∼ 0.4 mm (0.008 ∼ 0.016 in.)

NOTEAbove procedure must be used to insure proper coil airgap is not too large.

•Note the following.• Install:Ignition Coil [A]Bolts [B]Ground Lead [C]•When installing the ground lead, put ground lead betweensecond and third fin.

9-14 ELECTRICAL SYSTEMIgnition System

Ignition Coil Inspection•Remove the ignition coil (see Ignition Coil Removal).•Measure the winding resistance as follows.Set the hand tester to the R × 1 Ω range to measure theresistance between the terminals "A" and "B", and to theR × 100 Ω range to measure the other resistance.Special Tool - Hand Tester: 57001-1394Make the measurements as shown in the table.Ignition Coil Winding Resistance

+–

A B C

A – 300 ∼ 400 Ω 4 ∼ 6 kΩB 300 ∼ 450 Ω – 4 ∼ 6 kΩC 4 ∼ 6 kΩ 4 ∼ 6 kΩ –

CAUTIONUse only Tester 57001-1394 with new battery atroom temperature for this test. A tester other thanthe Kawasaki Hand Tester should show differentreadings.If a megger or a meter with a large-capacity batteryis used, the ignition coil will be damaged.

If the tester does not read as specified, replace the coil.

Spark Plug Removal•Carefully pull the plug cap from the spark plug.•Remove the spark plug using a suitable plug wrench.Spark Plug Installation• Insert the spark plug vertically into the plug hole with theplug installed in the plug wrench.• Tighten the plug.Torque - Spark Plug: 22 N·m (2.2 kgf·m, 16 ft·lb)

•Fit the plug cap securely.• Pull up the spark plug cap lightly to make sure to installthe spark plug cap.

Spark Plug Cleaning and Inspection•Refer to the Spark Plug Cleaning and Inspection in thePeriodic Maintenance chapter.

Spark Plug Gap Inspection•Refer to the Spark Plug Gap Inspection in the PeriodicMaintenance chapter.

TROUBLESHOOTING 10-1

10

TroubleshootingTable of Contents

Engine Troubleshooting Guide ............................................................................................... 10-2

10-2 TROUBLESHOOTINGEngine Troubleshooting Guide

If the engine malfunctions, check if the way the engine is used is correct. If engine malfunctionseven if engine is used correctly, systematically carry out troubleshooting starting with simple points.This chart describes typical troubleshooting procedures.Do not unnecessarily disassemble carburetor, magneto or engine unless it has been found to be

the cause of malfunctioning.

TROUBLESHOOTING 10-3Engine Troubleshooting Guide

10-4 TROUBLESHOOTINGEngine Troubleshooting Guide

TROUBLESHOOTING 10-5Engine Troubleshooting Guide

Part No.99924-2099-01 Printed in Japan

vr[ - … · installing a new part, clean off any dust or metal filings. (2) Tightening Sequence...

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