Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/126011
Hgguchi's torguel tiddler Sidestep the 125cc rush and win on a 100cc mono By Charles Morey If you own a 125cc Yamaha Monocross and race it in the super 'c o m p e t i tive 1 2 5cc motocross class, you'll quickly understand Nogu chi Motors' seIling poin t for their new 100cc performance kit. Every Sunday, you line up beside 20-40 other anxious-to-win riders who are rid ing either ex act copies of your b ik e or th e equally potent CR125 Hondas or RM 125 Suzukis. The 125 cc Yamaha being the most popular bike in th at class today, it seems that almost everybody owns at least one of the little yellow zo n ke rs, And unless y ou either are sp o nsored b y a dealer that knows how t o d o a t rick ' port ing j ob, or have th e t ools, know-ho w and money to do it y ourself, yo u 'll ei the r have t o o ut ride o r out-brave everyo ne else on th e line in order to wi n. Now , fro m t he sp ect at ors' poin t of view, t hat 's just fine. Eq ual mach in es mean th a t close racing will take p lac e with (usua lly) th e most t alented rid er taking the wi n. Un fort unately, fr om t he ride rs' po in t of view, t hat's no t how it works. After all, t he shop -sp o nso red riders h ave an adv an t age . Why shouldn' t yo u? If yo u're in the p osition wh ere yo u' ve already co nsidered switching to a less in tensely competitive class, but you're not really ready for the added exp ense of a b igge r bike; c o ns i d e r th is alternative. Sleeve down your present mount and try the 100cc class. That 's the general path of reasoning that Mr. No guch i USA , Dave Townsley, follow ed in pl anning the newest addition t o t h e Noguchi line of performance kits for Yamahas. The task of t aking Townsley 's concept and transforming it in to reality Was assigned to t une r Woody Kyle. While not a fam ili ar n am e o n the motocross d rew t, Woody has built so me outrageously quick Kawasaki flat trackers, the deadly WKRs (Wo o dy Kyle Replicas).•A WKR c arried J ay Ridgew ay , in his 19 73 No vice year , to a second pl ace in th e Eastern Regional Ch ampionship s and helped him earn the title o f Cycle News Rider of th e Ye ar. In 19 74 , Novice Jeff Purvis Broadslid o ne of Woody's b ikes to t he t op of t he Eas te rn Regional Ch ampionships . It w as Kyl e who made the 350cc Kawasak i single co mpetitive th e do-or ·d i e , i n s l a m -b am - t h a nk-va-rna' am wo rld of r oundy round raci ng. The man builds ,a mean mo tor. Townsley 's t arget horsepower figu re for a ful ly developed , flat track tuned mo to r fell in th e 22-2 3 bhp range. In J ust bef ore our photo/r ide session , tuner and 100cc kit d esigner Woody Kyle put the finishing t ouches on th e " mini mo no." Fo r a 100cc machine, it's a jet. Wheelies? You bet ! Ju st grab a b ig handful once th e motor geU on the remarkably wide powe rband, and hang on. one of those rare twists of good lu ck , b ac ked by Kyl e' s know-how , t he firs t prototype reg istered 22.6 bhp at 1 1,000 rpm on Noguchi 's Patraco dyno! Needless t o say , they we re more than just pleasantly surprised. The amazing part of the situation is th at the 100cc kit co m es within t h ree bhp o f their 125cc ki t 's rating with no co o ling problems , an d actually claims a wider power b and than the stock 125cc Yamaha motor. The 100cc kit on the motor fro m a 125cc Monocross puts out wh at Townsley refers to as "rideab le horsepower" st artin g with 12 bhp at 8,000 rpm and go ing up t he 22 1/2 bhp figure at 11,000 rpm. As is the case with all Noguchi kits, t h e c y li n d e r / p ist o n changes . which comprise the entire us...ec~e"'" of putting out the horses, are supplied through new parts rather than rebuilds of your present equipment. The kit for the Monocross, priced at $299.95, includes an alloy cylinder head, head gasket, s t e e l-lin ed cylinder, cylinder gasket, p iston with pin , bearing and clips, pis t on ring, four-pe tal ree d valve , reed valve gasket, carb manifold, connecting rod, big end rod bearing and a ch oice of h igh or low pipe. Kits for th e YZ and MX models in clude a 30mm Mikuni carburetor, a stock item on the Yamaha Monocross. As yo u've no doubt surmised by reading the parts list , t he installation is no small job . It involves putting the new rod and bearing on your crankshaft; a job that would . probably run from $15-25 at a capable machine shop. Noguchi charges $25 to do the work, or if you prefer, they'll do the complete kit installation for $75 . Follow ing a session in the dirt, watching Noguchi rider Dennis Hall give the little 'm o n o a good workout and then taking a tum at the handlebars ourselves , vie couldn't find much to argue.abo'ut concerning Noguchi's claim of strong useable power. It 's the most impressive . 100= MXe r we've ever had the pleasure to ride. _ Here's the trick stuff; All th ose shiney ower-sized ports de liwer th e charge into th e combu stion chamber controlled by the " sli\tltly trimmed" piston. 39