Cycle News - Archive Issues - 1980's

took p lace a t a su nswept Sn euerton in mid-O ctober , with yours truly a t the helm for m y first tas te of 160 bhp p lus SO Occ mot orcycling. And to cap th e experience, the first tim e I' d sampled the new-gen erat ion ca rbon carbon bra kes th a t becam e a sta nda rd piece of high -tech G P hardware (a t lea st o n th e Suzuki ) during the co u rse of th is season. Suzuki co m p le te ly redesigned thei r SOOcc V4 for 1989. According to Schwa n tz's ch ief mechanic Simon' Tongue, th ere' s scar cely a single part from before that will fit th e new bike. Perha ps because of this, the pr eviously open Suzuki pit became a haven of secrecy this season , as th e factory imposed a security blanket which m ea nt tha t th e new X R75 va r ia n t o f th e twi n- crankshaft , cra nk case reed- valve V4 eng ine was rarely seen or photographed with th e fairi ng off . But litt le by little va rio us de tai ls lea ked o u t, u nt i l it wa s poss ib le to bui ld up a co m p lete p ictu re of th e new bike. Sc h wa ntz 's '88 X R74 h a d two mai n a reas of. needed improvem ent by the end o f last seaso n, and a host of mi nor o nes. Most critica l, though, were the need to slas h weight dr asticall y fro m the p revious 286-po und, half-dry weig h t (a lm ost 10% more tha n th e Yamaha YZRSOO ), a nd to mak e th e b ike more ridea ble wh en fi tted with th e new p ipes a nd cyli nders whi ch appeared mid-season a nd permitted Suzu ki to ca tch up wi th H o nda in terms o f ho rsepo wer a nd spee d - but o n ly a t the expense of a narr ow 2500 rpm powerb and an d very su d de n mid -ran g e d el ivery: 12,500 rpm wa s max , a n d th e step in th e power curve a t 10,000 rpm made the b ike ha rd to liv e with in turns . But Suzu ki 's sma ll, 30-ma n race de pa rtment - a frac tio n of th e size of HRC or even Yamaha 's race shop - kn ew wh at was needed , and spent mu ch of th eir tim e d uring 1988 working o n th e new '89 mod el , even a t th e expe nse o f updating th e X R74 as much as the y m igh t ha ve. T h a t this wa s th e co rrec t po li cy was dr a matica ll y co n firme d wh en Sch wa ntz wo n the first G P o f the seas o n in J a p an o n the a ll- ne w XR 7S, wh ich proved hi gh ly co m pe t. it ive with th e H onda a nd Ya maha op positio n from th e very fir st race. At the o the r end o f th e decade whose sta rt h ad seen th em wi n back-to -bark SOOcc tit les with th e RG SO sq uareO four, Suzuki wa s back in busin ess! The bi ggest cha nge in the XR7S' mot or over its p redecesso r is th e rephasin g o f th e tw in crankshafts, form erl y bo th ro tat ing in th e same fo rwar d direction, but now co ntrarota ti ng like the Yamaha and Cag iva V4s. This h as so many ben efits , one wonders wh y the y di dn't do it before. Among t h ese a re redu cti on s in weight (than ks to el im in ation of th e interm edi a te gear), frict ion , vibration and gyroscopic effect. T ha t's a lo t o f subtraction, bu t in terms o f add ition th ere's more horsepower a t hi gher revs - over 160 bhp at 13,000 rpm . Intensive work on th e sixtransler/three-exhaust port cyl inde rs, n e w pipes a n d a re vi sed el ectronica lly- controll ed variab le e x ha us t volume sy ste m u sing a cylindrica l power va lve ena b les th is figure to be a ttai ned wh il e at th e sa me tim e broadening th e sp rea d of power a nd smooth in g th e m idr ange deliver y. That 's qui te a tri ck , if you ca n manage it , a n d Suzuki 's sma ll team o f enginee rs has achieved just that. The n ew engine is much more com pac t as well as ligh ter th a n its . predecessor, w it h a n in cluded cylinder a ngle o f a bo u t 65 degr ees, but sti ll fea turin g a side-loadi ng extract ab le gea rbox (n o w fitt ed wi th an oi l pum p for the firs t tim e) with a huge choice o f ra tios for eac h gear: six each for th e bottom two speeds, no less than 13 for the middle two , a nd five eac h for fifth and sixth. Equ all y vas t is th e c hoice o f a lte rnat ive c h i ps fo r th e prep rogra m mab le Nippondenso co m p u terized ig ni tio n: literall y dozen s o f m icrochips offering subtl y different curves to choose from , th ough in h oneycomb chassis for th e works . bikes in the mi d -80s. Co u p led wit h the sm a ll er , m ore co mpac t a n d lighter en gin e, th is resu lts in a n impressive weight savi ngs for the new XR75, which sca les 264 pou nd s with o il/wa ter bu t n o fue l - fu lly o n par with H onda and Yamaha. En gine designer Yos hida , chassis designer Manabu Suzu ki, a nd th eir respe cti ve tea ms must have been pl eased with th eir work, even befo re th e first GP a t Honda 's home base of Suzuka p roved just how succes sfu l th eir efforts h ad been. " Yo u loo k a t th e new Suzuki, a n d you ca n see th at everywhere H o nda would ha ve used a seven -m illim eter nut, Suzuki used a six -m illimeter one," co m me nted Erv Ka nem o to in graphi c appreciation o f the riv a l team's weigh t-saving effort s. Did they go too far, judging by the tri o o f breakdowns suffered la ter in th e season? " T he re migh t be an eleme nt of that ," admits Simon Tongue, " b u t the three breakages were a ll different, and had ne ver bee n experienced befo re either o n the dyn o or in track test ing. I'd say o n ly th e H ockenheirn reti rem ent co u ld ha ve been ca used by going too ligh t on ma teria ls to save weight, a nd then Kevin was way overre vving it , any wa y. T he o the r It p u ll ed fro m so low dow n as I exited th e Sne tte rton p its th a t I bet they felt th e shock waves in Austra lia. T h ere was m oving p ower a t 6000 rpm , usab le p ow er fro m 7500 a nd Rich tersca le m ot ivation fro m a ny w he re above nine grand u p to peak horsepower revs of 13,000 - a n d beyond. Slightly u ndergeared for Sn etterton 's ma in straig h t, I saw the tac home ter needl e reg u larly climb to 13,SO Orpm wi thout more tha n a slight notice ab le . drop in power, a nd on o ne occasio n w hen I got rea lly brave with m y braking at th e end of th e straight, to 13,700. O nl y later did I remember that " Kev th e Rev" lived u p to his name at H oc ken heirn, revving it th is high and end ing up breaki ng a cra n k bearing ... If th e overrev ca pa bility the Suzu ki V4 engin e now possesses is impressive, it pa les beside th e smoothness and progressivity o f that m ega : power o ut p u t, and th e widt h ofthe powerba nd. Su zuki ha sn 't foll o wed Ya m aha 's lead fro m a couple of years ago o f obtai ning H on d a -bea tin g power b y n arro w in g the su perpowerban d (as Su zuki did themselves. last year), no r does th e XR 75 have a Cagiva -like step in th e deliver y whe n th e power valve is full y open. I nstea d , th e h o rse p o wer b uild s strongly but smooth ly fro m arou nd (Right) AP carbon brakes and Kayaba upside-down forks grace tbe Suzuki'll front end. (Below) - The RGVliOO sans bodywork WIUI a 81ght Ilel d o m seen by reporters In 1989. pract ice th e team tends to sti ck with two wer e j ust faulty components, wh ich yo u ca n' t rea lly foresee ." one o f a handful o f suitable ones. There's no faci lity for "cookin g" Wha t I co u ld fo resee as I ho p ped th eir own ch ips (like o n th e Du cati aboard the RG V Su zu ki a t Sne tterto n and Bim ot a Superbi kes ' Marell i/ was a frantic 20 laps, tryin g desperWeber engine ma nagem ent systems ), at ely to hang onto a 160 bhp-plus because th e Suzu ki is still fitted wi th ro c ke ts h ip w it h a fi erce p ow er car b u re to rs , the sa me du a l-b od y d e livery a n d un compromi sin g . handling. 36m m Mikun is th a t th ey, Yamaha a nd Cagiva ha ve used for the p ast Well .. . I ca n 't say it wa s like - ridi ng a ste p -th ru m o ped , exactly , co u p le o f seaso ns. One ge ts th e feel in g Su zu ki has reach ed a prag b ut th e Su zu ki tu rn ed o u t to be m ati c decision that EFI ca n wait now here near. as intimi da ting as I'd u nt il someone else h as made it work antici pa ted. on a two-stroke G P bike. T he main reason fo r thi s is the T he new engine is fitt ed in to a n ex trem e flexibil it y a n d su p re m e eq ua lly new chassis , much m ore co ntrollab ility o f the XR 7S engine's refined in desi gn a nd co ns truction power delivery. If la st year's b ike was tha n Suzu ki's previous efforts si nce hard to ride, thi s o ne must h ave re-start in g .G P chassis co ns truction , seem ed li ke o ne of th e bi g fourth em selves after th e era o f the Hero n strokes Kevin cut his ra ci ng teeth o n. 9000 rp m .u p to th e excesses of o ver revvi ng, m aking it more lik e a hyperquick street bi ke th an a fu ssy, pea ky G P racer. (T oo bad Suzuki got cold feet an d cancelled th eir proposed road-goin g RG V5OO1) At 12,000 rpm , ther e 's already mo re th an ISO bhp on tap, so the ho t tip is to try to keep th e engi n e spi nn ing above th a t ma rk, a tas k m ad e easy by th e set o f rat ios fitted for th e test. Su zuki terms th is th e " 0" gearbox, with the close b ut even lyspaced rat ios ha vin g a n average of 700 rp m bet ween .gears o n th e leftfoo t, o ne- down, stree t b ik e sh ift pattern th at Kevin favo rs. At th e same ti m e, th e engi ne is so torquey a n d flexib le yo u ca n not on ly short sh ift it wh en necessary (like jus t before h itt in g th e bumps as you la y it into th e lo n g rig h t-hander a t Coram, ena bling the ba ck wheel to ride o u t the ro ugh stu ff more co mfo rtabl y in a hi gher fo urt h gear tha n a twitchi er, high-revving th ird ), but a lso use th e low -down pow er to co me o ut o f slo wer tu rn s faster (like a t th e Sne tter to n H a irp in/ Esses). Usi ng bo ttom gea r comi ng o u t o f tigh t tu rns makes th e bac k wh eel spi n a nd

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