Cycle News - Archive Issues - 1990's

TECHNICAL World Championship Superbike Series YAMAHA: Still Good Enough! a mah a had a n enco uragin g start to Y th e season at Donington, with Terry R ymer 's ove ra ll win o n h ome ground , a nd a close second to Pol en in the first leg ma tched by Fab riz io P i r o va n os ro str um pl a ce in th e second . T hese two are th e only factorybacked Yamaha riders in World Superbike th is seaso n , th o ugh so far tha t does n 't a ppear to have a mounted to a great dea l in th e way of spe cia l factor y parts, p erha ps develo p ed from th e Su zu ka 8-Hou rs-w inning YZF750R . Ins tead, whe n the Bri tish and Ita lia n tea ms received thei r tr ick parts o n ly a week befor e the Doni ngto n round , th ese turned ou t to cons ist o f a facto ry cyli nd er h ead with the sa me ca ms hafts and co m b ustion cham ber as the ki t engine everyo ne else on a Yamaha uses, but with th e va lves a nd seat s in a different ma terial, for lon ger life. Val ve sizes are unch anged , but th e head has been ported and £lowed . A pa ir of titan ium exha us ts wer e a lso supplied - a ra th er wasteful use o f budget , con side rin g th a t bot h teams have to ba llast the i r bi ke s wit h n on fu nctioning a lterna tors to bea t the weigh t lim it (on e of Rym er 's b ikes was sent to scru tin eer ing a t Do n ington withou t this vit a l com p onent, and was pro m p tly turn ed down a s un d erweigh t!). O ne o f these h as the EXUP fitt ed . th e o ther no t, but on ly R ym er tri ed th e non -EXU P p ipe, wh ich ga ve a smoother deli very low down a t th e expen se of top en d power. P irovano 's tun er Beppe Ru sso , who do es a lot of h is ow n developmen t o n h is ow n dy no in Monza , a n d who may be cred ited with th e exceptional perfor mance of th e little Italian 's bike at th e en d of last season, al ways uses th e EXU P system because he finds it gives bett er accele ratio n a n d midrange perfo rman ce. Pi rovano 's 1991 b ik e delivers 141 bhp a t the gea rbox , at 13,500 rpm, bu t an interesting th ing is th at both reams h ave been recommended by th e Yamaha facto ry to ru n a rel a tively low co mpress io n th is year, a nd the kit pisto ns th ey've been su p p lied wi th now give 'o n ly' abo u t 12.5:I co m p ression . O therw ise, th e engi nes are little cha nged from las t year, a nd the sa me appli es to th e chassis, bo th u sin g Oh l ins suspensio n as you wo u ld exp ect seeing as how Ya maha ow n a m aj o rit y sh are in t he S wed is h co mpan y! T he on ly new fac tory chassis p art for this year is a large, n icel y-m ad e radi a tor, which Ru sso decli ned to bo th er fitt ing on the groun ds th at th e old one was go od eno ugh for a spring day a t j arama ! Loctit e's Ad rian Gorst di d fit th e n ew rad to R ymer 's bikes, t ho ugh, and rep orted j u st 65- 70° wi tho ut u sing th e su p p lem entary , sma lle r radia to r for the ch in o f th e fa irin g wh ich ca n be employe d la ter in th e year as the wea th er hea ts u p. The O h lins rear has a new lin kage offeri ng a different curv e which nei th er team h ad so rt ed o u t pe rfectly yet, tho ugh P irova no's bi ke on Mich eli n s look ed to be han dling be tter th an T erry's on Dunl op s in Spa in - or ma ybe it was just th e way th e tall Bri t rides 'em ! You co u ld hardl y find two more d isp arat e rid er s in terms of sta ture or personal it y on th e same bik e, one a cheerfu l, lan ky gu y who n ever Fred Merkel's Honda RC30 has yet to finish a rac e in 1991. The bike features few changes a shorter swingarm and Showa upside down forks give the bike a I5mm longer wheelbase. Merkel's Honda uses Brembo iron brakes, but may be fiued wi th carbons soon. looks as big on the bi ke as he do es o ff it, th e o ther a sma ll , in tens e pocket rock et whose sea t pad wei gh s an unbelievabl e 5.5 lb. just to p ro p him in p lace - that shows how much weig h t the Yama ha has to spare, if noth ing else: in a free formul a , th e a WOl co u ld eas ily hit th e 34 1 lb . ma rk Dress properly for your ride with a helmet. eye protec tion . long -sleeved shirt. long trousers. gloves and boots. Yamaha and the Motorcycle Safety Founda tion encourage you to ride safely and respe c

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