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MOTORCYCLE DIVISION 4-STROKEBULLETIN GS/GSX/GSX-R NO. 139 RevisedDATE: 3/21/2006

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Parts Information

SUBJECT: GS500F ENGINE KNOCK AT IDLE

AFFECTED UNITS: GS500FK4/K5 - ENGINE NUMBER M504-125865 & EARLIER

REFERENCE: GS500 SERVICE MANUAL (PN 99500-34094-03E)

NOTICE:This bulletin is a revision to the original Service Bulletin GS/GSX/GSX-R NO. 139 dated5/2/2005. Please place a copy of this bulletin with your dealerships Service Bulletin binderand GS500 Service Manual and discard the original bulletins.

Some GS500FK4/K5 motorcycles may exhibit a mild but annoying knocking noise fromthe cylinder head area. This sound will be heard only at idle or just off idle.

SolutionThis knocking noise may be caused by the camshafts walking side to side during operationdue to excessive end play. The walking movement will not cause damage.

Note: Test the source of the noise for camshaft walking by carefully leaning the

motorcycle over to the left (toward the sidestand) while the engine is running and continueto listen for the noise. The noise will quiet if the camshafts are loaded toward the left handside.

Should you receive a complaint of the above described symptoms, follow the procedurein this Service Bulletin.

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AFFECTED DEPARTMENTS:The following departments in your dealership should be notified of this information:

Management Service Warranty Sales Parts AccessoriesAmerican Suzuki Motor CorporationTechnical Service DepartmentMotorcycle / ATV

2.Replace the exhaust tappets using the original adjustment shims.

3.Assemble each new replacement camshaft with one of the original 1.0 mm thickwashers at the left side and the two 0.7 mm thick washers mounted on each side ofthe wave washer on the right side. See Figure 1.

4. Install the cam sprocket with new washers and time the camshafts (refer to ServiceManual, beginning on page 3-56).In the timing position, the exhaust camshaft lobe presses on the #1 cylinder exhaustvalve lifter. In this position, the bearing surface can easily be damaged by the additional

washers if care is not taken when the camshaft journal holders are installed. To preventdamage, rotate the crankshaft 90 in the reverse direction while ensuring that the chaindoes not become detached from the sprockets.

5. Install the camshaft journal holders and tighten the journal holder bolts to the specifiedtorque. Install the cam chain tension adjuster (refer to Service Manual beginning on page3-59), confirm that the cam timing is correct and adjust tappet clearance if required(refer to Service Manual beginning on page 2-5).

Procedure

1. Remove the cylinder head cover, camchain tension adjuster and camshafts(refer to Service Manual beginning onpage 3-10).Remove the sprockets and the 1.0 mmthick thrust washers from the original

camshafts. These parts will be reusedwith the new camshafts.

Left side Right side

Thrust wash-ers

Thrust washer(t=1.0mm)

Wave washer

FIGURE 1