Cycle News - Archive Issues - 1990's

; TEST Yamaha YZR500 e Wayne Rainey's title-w weapon inning circuit, and finished on the rostrum in every other race - a fine ach ievement reg ardless of th e depleted numbers in the 500cc class last season . Seven GP race victories, five seconds and a pair of thirds gav e Rainey, Yam ah a and Kenny Roberts a welldeserved title. . In a year wh en co nsistency and reliability were the keynotes of championshi p success, it was ap propriate th at Ra in ev's titl e win sho u ld be ach ieved on ' the most depe nda ble and lon g-lived machi ne in the current GP lineup - Yamaha 's YZR500 V4. Since taking the maj or step of converting the twin- crankshaft V4 design , whi ch the .were the first to in trod uce to the mo dern G P arena, from rotary-valve . to reed-val ve ind uction back in I98-t, Yamah a has follo wed a predetermi ned evol utiona ry develo p ment po licy on thei r 500cc bike, ju st like Hon da has don e with their 250cc V-twin . Where Honda, Cagiva an d latt erl y al so Suzuki ha ve go ne in for 500cc redesigns almost on an annual basis, Yam ah a has been co ntent to co nsta nt ly u pdate their basic mach in e, so that Ra iney' s 1990 title-winner is recognizabl y sim ilar If;> Eddie Lawson's 1984 cham pionship mach in e - and not just becaus e of the Marlboro colors! T hat mak es Yamaha' s victory last season a triumph of evolutio n over revolution - rather like Po rsch e' s poli cy with their rea rengined 911 spo rts car, even longerlived but th e subject of co ns tant updating - and mea nt tha t the Team Roberts Marlboro titl e-w inner 1 samp led on an initiall y damp Sneuer- By Alan Cathcart Photos by Phil Masters enny Roberts surely won 't forget 1990- the year it all finally came togetlier for the three-tim e World Champion in his more recent role as GP team manager. After five years of constant striving to win a coveted world titl e as boss of T eam Robert s Yam aha , 1990 sa w King Kenny 's dream realized - not once, but twice. After coming so close in 1989, Wayne Rainey turned in a near -copybook season to win th e 500cc titl e, while KR 's fu tu re investment rid er-wise, J ohn Kocinski, won a thrilling 250cc cha mpionship chase at the last ga sp in Austral ia. The best racer of hi s era had now become th e best team manager with a clean sweep of hi s targeted tit les: Not reall y mu ch more you could as k for, is there? Severa l facto rs combined to mak e .this possible, especia lly in the 500cc class where until this season, there had alwa ys been at least one 'p iece missin g from the jigsaw of factor s combi ni ng to make a T eam Roberts title win feasi b le . Astu te beh ind -the-scen e's man agement ena bled Roberts to brin g it a ll toget her for 1990, with a switch to Marlboro sponsorship p laci ng a much larger budget at h is disposal, whi le an agree ment with Yamaha saw Team Roberts install ed securely as effectively the facto ry wor ks team , with all other Yam ah a users pla yin g second fiddle to the Marl boro-Roberts setup. Hiring rei gnin g World Ch am p ion Eddie La wson a longside his close rival Rainey not on ly beefed up the rider strength to a level never previously attai ned by any team , but a lso seemed likely to spur each rider on to new levels of competitiveness by mountin g them on equal machinery. And finall y, yet in some ways most vitally, T eam Roberts switched to Michelin tires for th e fir st time, aft er four years o n Dunlop rubber, though remark abl y enoug h 1989 titl e runner-up Rainey sta rted th e. 1990 season ha vin g to qualify for the best A-tires in pra ctice K 8 un der Mich elin's cont roversial new system, since each leading team was restricted to just one guaranteed set of the top rubber. All the pieces of the j igsaw were on 'the tabl e: now it . remained to assembl e them toge ther. The man who did tha t was Californian Wayne Rainey, who took the cha mp ionshi p battl e by the scru ff o f its neck in Japan by leading the first race of the season from start to fini sh to impress his mark on the titl e chase. From then on, everyo ne el se was playing ca tch-u p - th at is, when they weren 't crashi ng and injuri ng themselves. With horsepower levels now over 160 bhp, weight of theHonda and Suzuki works bikes at least down to th e 253 lb. class minimum and Michelin tires of the hi gh est level yet seen in G P racing, even the leading handful of the world's top riders found contro lling th eir mega-rocket race bikes a tricky bu sin ess in 1990 - all excep t Wayne Rainey, that is. In a practi call y. faultless seaso n Rainey cras hed just once, in qualifying in Germ an y (fro m whi ch he recovered to fini sh second in the race), likewise DNF ju st once in Hungary when a lat e swi tch from carbon to steel brakes left him with insuffici ent brake fluid in the system to cope with the high level of pad wear on a switchback ton tra ck at the end of th e 1990 season was ' very similar in feel and performan ce to its 1989 pr edecessor - on ly even fa ster! Simi lar, th ough, but not identical: Here's wh y. In updating th eir twin contrarotating crankshaft V4 engine for 1990 in search of more power wi thout sacrificing the usability that has long .been the YZR500 's trad emark, Yamaha widened the angle betwee n the two banks of cylinders to 80 degrees, in order to offer more space for bigger reed-valve boxes and thus better breathing. Slightly larger 35.5mm dualbody Mikuni carb s were fitted (36.5mm for Salzburgring), but unlike on the

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