WORLD-CHAMP FEATURES WITH AN RTR PRICE

KYOSHOINFERNOMP7.5 SPORTS 4

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KYOSHO HAS BEENproducing 1⁄ 8-scale buggies fora long time, which means theyknow what they’re doing. Theyhave several world titles undertheir belt and have now builtyou an RTR buggy that uses thesame geometry and materialsas used to produce thoseworld-winning rides. They toneddown a few of the componentsin order to lower the overallcost of the buggy and havebuilt it to get you from the boxto the track in no time. They call their RTR buggy the InfernoMP7.5 Sports 4, and it’s thelatest and greatest version ofpast RTR buggies based on thesame platform. Let’s see whatthis new buggy offers.

WORDS KEVIN HETMANSKI ❯❯ kevinh@airage.comPHOTOS HOPE McCALL

TEST DRIVE

Type 1⁄8-scale RTR 4WD buggyPrice $385 (varies with dealer)Wheelbase 12.8 in. (325mm)Width 12.1 in. (307mm)Weight as tested 7 lb. (3,177g)Clutch bell/spur 13/46Final drive ratio 11.7:1Chassis 3mm aluminum plate withradius sidesDifferential(s) Triple-sealed bevel gearSuspension Front lower A-arm/rearlower H-arm with adjustable upper linksShocks Aluminum fluid-filled coil-over

SPECIFICATIONS

■ RTR ■ NITRO ■ OFF-ROAD

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THE ENGINE RUNS VERY WELL, PUTS OUTGOOD POWER AND HAS A SMOOTH FEEL.“ ”

Kyosho Inferno 4/23/09 11:37 AM Page 75

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KYOSHO INFERNOMP7.5 SPORTS 4

CHASSIS. The backbone ofthe Sports 4 is a 3mm blue-anodized aluminum plate andfeatures radiused sides toincrease stiffness. Moldedplastic mud guards areattached to the sides of thechassis to keep debris out. Theleft rear of the chassis hasbeen machined to accept theKyosho GS21’s unique enginemounts as well as standardengine mounts. All screw holeson the bottom of the chassisare chamfered to keep the bot-

tom as smooth as possible,and small divots under the diffsallow them to be mounted aslow as possible. A rear braceincreases the stiffness of thechassis and you can add anoptional front brace if you feelthat the chassis needs morerigidity for your driving condi-tions. The radio tray and boxare bolted together and can beremoved in one piece to makeit easier to clean the chassis.The top plate is made out ofaluminum and it’s supportedby plastic posts. Kyosho even

threw in a transponder mount.

DRIVETRAIN. The engine isconnected to the drivetrain byway of a two-shoe, composite-type clutch. The clutch bellrides on a roller bearingassembly and mates with amolded plastic spur gear. TheSports 4 uses a 3 diff drive-shaft system to get the powerto the tires and all the diffs aresealed, which means that theycan be tuned by changing theviscosity of fluid that you placeinside them. Dogbone-style

center driveshafts connect thecenter diff to the front and reardiffs and you’ll find dogbone-style shafts spinning the reartires while universals are usedup front. Metal-shielded bear-ings support the entire drive-train and ensure wear-freeoperation.

SUSPENSION. Up front you’llfind a lower A-arm with upperlink and in the rear, a lower H-arm with an upper link-typesuspension system. The upperlinks use steel turnbuckles

FEATURES

THE RADIO TRAY AND BOX ARE BOLTED TOGETHER AND CAN BE REMOVED IN ONE PIECE

TO MAKE IT EASIER TO CLEAN THE CHASSIS.

The KyoshoPerfex radiois included

with theSports 4. Thisreliable radio

fits well inyour hand.

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JULY 2009 77

Once again, Kyosho has given usa great backyard basher and abuggy that is perfect for the first-time racer. Its hop-up potential isendless, and you can’t beat thedurability of an 1⁄8-scale buggy.Fewer broken parts frees up cashfor more “go” parts. Out of thebox, the only things I wouldchange are the tires to somethingthat’s a little softer to take advan-tage of the engine’s power. I’dalso tighten up the servo-saver abit to make the Sports 4 moreresponsive in the turns. Overall,it’s a great buggy.

With the batteries in place and the engine broken in, I headed to Wolcott Hobbies in Wolcott,CT, for my buggy’s first rundown. I filled the tank with Byron 30 percent nitro, fired the engineand gave it a quick tune. I’m very happy with the location of the low-speed needle and idlescrew. With a little lift of the body, they are very easy to access. I put the buggy on the trackand made some laps and right away, I could see that they were way too stiff for the tracksurface I was running on. I took the Sports 4 up behind the track where the dirt is moresandy and loose and the tires hooked up much better than before. Since I wanted to do mostof my testing on the track, I swapped out the stock tires for a set of AKA Crossbrace tires,and they brought the buggy to life. It’s so much easier to control with softer rubber. Withsome race rubber on, I started making hot laps around the track. The stock steering servodoes pretty well in the turns. It’s a little slower than what I’m used to, but perfectly fine forbombing around and I had no trouble making the turns on the track. I tightened up the servosaver a little and that improved steering response. The engine runs very well, puts out goodpower and has a smooth feel. At first, I did notice a little slip in the clutch, but the feel of itstiffened up as the day went on. Braking on the Sports 4 was smooth and strong. I didincrease rear brake slightly to help the buggy rotate better in the turns. Jumping any 1⁄8-scalebuggy is a pleasure, thanks to the ability to change the angle of it while in the air by tappingthe brake or throttle. The Sports 4 soaked up landings well. I took the buggy back behind thetrack for more of a bashing-type surface to see how it held up to some trashing and I didn’tbreak a single part. This thing can take some hits!

and allow you to change yourcamber settings without hav-ing to remove the upper linksto do so. The shocks are alu-minum-bodied units and useclamp-type ride heightadjuster to keep the springs inplace. The top of the shocksare attached to 3mm-thickblue anodized aluminumshock towers. You have fourmounting positions availableon the front shock tower andsix in the rear shock tower toaid in suspension tuning.

ENGINE & ACCESSORIES.The Sports 4 comes equippedwith Kyosho’s GS21 engine.Some of its features are asmooth slide carb, easy-to-access, low-speed needle andidle screw, lightweight 7-finheat-sink head, bolt-on headerand pull-start. The engine canalso be started with the use ofa starter box. The exhaust exitsthrough a multi-piece, cast-tuned pipe and a rubber cou-pler attaches it to the header. A 125cc fuel tank feeds the fuelto the engine through a small

section of fuel tubing and it hasa small fuel dam molded intothe top to direct any spilled fuelaway from the brakes and outthe bottom of the chassis.Molded dams inside the tankhelp keep fuel towards the fuelfilter/pickup in the rear of thetank. The air filter has plasticcups on each side to keep theair filter cleaner so the enginecan breathe better while bomb-ing through mud and water.

BODY TIRES AND WHEELS.The body comes painted,

trimmed and mounted and hasa cutout in the back by theengine for easy pull-startaccess while the body is inplace. Thanks to the two bodyclips that hold it in place, thewing in the back of the buggyis easy to remove. You canadjust its angle to increase ordecrease rear downforce.Firm, multi-spiked tires areincluded and are supported bystrip-type foam inserts. Theycome glued to attractive multi-spoke wheels that slide onto17mm hexes.

Kyosho gives you a Perfex KT-6 radio tocontrol the Sports 4 buggy. It has featuressuch as dual rate, throttle and steeringtrims, and servo reversing. A bright redLED lights up to let you know that theradio is turned on. A pair of Perfex 102BKservos takes care of the steering, throttleand brake controls. They have plenty oftorque for throttle and brake but might bea little weak for steering. Kyosho providesa 4-cell AA holder to power the servos, butthere’s plenty of room in the radio box for a5-cell rechargeable pack, if you choose toupgrade.

■ 12 DURACELL AA BATTERIES ■ AKA CROSSBRACE TIRES ■ BYRON ORIGINALS 30% NITRO FUEL

SOURCESAKA raceaka.comByron Originals byronfuels.comKyosho kyoshoamerica.com

PERFORMANCE

TESTGEAR

VERDICT

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-

PLUS/MINUS

INCLUDED ELECTRONICS & ACCESSORIES

❯❯ Classic 1⁄8-scale durability

❯❯ Lots of hop up potential❯❯ Minimal effort to go

from box to dirt

❯❯ Weak steering servo❯❯ Hard compound tires

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