Cycle News - Archive Issues - 1990's

up th e hi ll at Suzuka behind the pits, presented eq ua l difficu lty. " I co u ld see yo u were h a vin g troubl e ge tti ng it to steer properly. up the hill, " said a sympa thetic Mick Doohan during the lunch brea k. " I . follo wed you through th ere and it was do ing th e sa m e as my bi ke did . all la st season - keeps wanting to wash out th e front end ." Too right, mat e - it 's j ust a basi c understeerer, either on o r off the power, whi ch th e locked -o n steering on ly exacerbates, so that you can 't even p ull it back into line physica lly, or by layin g it over a bi t harder, which th e grippy ' A ' Mic h e l i n radials will certainl y let yo u do. There are o n ly two so lu tions to thi s rather serious problem, one of which I'm riot eit her q u a lified or bra ve enough to do, w h ich is to powerslide it ro u n d th e tu rns broadside (for dem o , see '89 Bra zil G P video, M. Doo han dem onst rating). T he o ther way, which al so doesn't p u t suc h a stra in o n yo ur rear tir e, is to do it th e Lawson way: wide, swee p ing (Right) Honda 's World Championship-winning 1989 NSR500 featured a redesigned chassis, but its success revolved around its Vfour engine (below), still of a single-crank design; (below right) Lawson had a cho ice of two exhaust des igns in 1989: not e carbon f iber silencers. a rcs, mainta in ing momentum by drift in g th e back wheel so th a t it steers a touch , but no t n earl y as much as Method One. T h is way , yo u h ave a ch ance o f co u nteri ng th e tig htturn in g , fire-'er -out antics o f Revvin ' Kevin a nd th at remarka ble Su zuki. Th e H ond a 's unrul y be havior stems fro m a series o f com promises, each of which ha ve a kn oc k-o n effect. HRC redesign ed th e chassis for '89 to offer improved stabi lity a nd traction co upled with more p redictable steer in g th a n th e '88 b ik e. T rying to sa tisfy th ese co n trasting an d so metime co n flicting req uiremen ts (co upling fast steeri ng wi th stabili ty on fast co rners for exa m p le) ha s resulted in so me prett y ra dical steering geometry o n th e bike 1 tested representing th e '89 NSR500's fin al sta te of evolution: a 22-degree head a n g le , minim al tr ail o f 83mm , weight distribution of 55/45% static (53.5/ 46.5% with a rider aboard of Eddie's 136 lb. weight) and a wheelba se of l395mm . H RC pla yed around with these figures d u ri ng the season, as well as altering th e ride heigh t, but th a t's what it en ded up as. The smaller 16-inch front whee! combined with the reduced gyrosco pic effect of th e carbo n br ak es while they were used to assist that steep h ead angl e and minimal trail in speedi ng up th e steer ing: even a fter Eddie revert ed to th e steel dis cs, th eir adverse effec t was par tia lly co u n tered by th e use o f so me carbon fiber whee ls HRC dug ou t from th e store whe re th ey'd lain unused since th e Spence r da ys, th ough d ue to the ir as tro nomical cos t th ere were no new ones forthcomin g: even H o nda has budget lim ita tions, though with th e news tha t Marvic will be selling carbon wh eels for the 1990 season, perha ps that problem may be red ressed too! T he resu lt of a ll th is is that th e NSR500 shou ld indeed be a fas t steerer - exce p t th at th ese figures have a lso resu lted in a bike th at lacks stab ili ty in a straigh t lin e, especially whe n it becomes unsettled by a bump - which means yo u have to cran k th e steering damper right up tight! This in turn negates a large part o f wha t yo u just achieved by op tin g for those radi calgeom etr y figures, and makes th e bike a real handful in slow corners as well as contributing to it s reluctance to stay on lin e close-in on medium -speed turns - which is where we came in . Welcome to the domino th eory of motorcycle devel opment - who sa id chassis design was easy?! Honda never m anaged to balance . thi s eq ua tic and for th e penultimate ra ce in Czech o produced a ne w chassis for Wa yne Gardner that for the first time had the engin e in a differe nt p lace, lowerin g the cen ter o f gravi ty in a theoretica l a ttem pt to speed u p th e handl in g . Tsunoda is ca ndid a bo ut th e resu lta n t camel: " It wa s my idea and it d id n 't work: Wa yn e found it . u n ma nageable, cra shed it in qua li. fying and missed th e ra ce!" The fact that the 'stoc k' NS R cha ssis proved adequatel y sta b le ro u n d fa st co rners like th e left hander a t th e end o f th e Suzuka back stra ight doesn't rea lly mak e up for this, because th er e a re a lot more slow tracks a n d slo w corners in the G P ca le nda r th an fa s t ones - a nd a ny way, th ey sti ll better no t be b u m py: eve n w ith th e s teeri ng dam per full -on wh ere Edd ie a lways ra n it, th e Honda still weaved a nd wo bbled p ast th e Suzuka pits eac h la p. No wo nder Mr. La wso n loo ked so drained after eac h race, with th e p hys ica l as well as m ental effort this behavi or exac ted from him this season . A Hero... Oka y, you say - but co me on : th is bike won th e hardest-fo u ght 500cc title chase in recent years, so it ca n' t be th at bad! Well , 1 would o n ly say a fte r riding th e lat est NSR that H onda wo n in sp ite of th e' chassis; th anks to Eddie 's bri llance, a n d because o f th e phen omenal perfor- m ance of th e V4 engine : once aga in, H on da produced th e fas test bik e of its class - bu t th ey did so without ha vin g 10 resort to na rro wing the power- ba nd Cagiva-stv le, For the first time sin ce th e singlecran k V4 wa s introduced in 1984, HRC did not redesign th e motor for th e new season, as evide nce d by the number s NS R500E-8806 born by th e test bikes' engine , as used a t G oi ania. Thus not onl y the ma gn esium cra n kcases but also th e o vera ll design of th e 54x54.5m m cra n kca se reed -valv e eng ine remained un cha nged for '89, though HR C does adm it to trying out a prototype 'Two -Up' motor earlier in th e season with th e cylinders firin g toget her in pai rs, rathe r th an individ ua lly in seq uen ce, as usu al. T h is revised la you t was raced on ly once, by Mi ck Doohan in Spai n , a nd th ough he reported a littl e more torque, it wa s a t th e expe nse o f top en d power - so me th ing H onda had traditionall y pl aced a high prem ium o n! So th ough Lawson tested th e 'Two- Up' again la ter in France, it wasn 't ra ced again a nd according to T sunoda rem ains a proj ect tha t H RC will develop fu rt her to site if it offers a ny real overa ll ben efit. Lik ew ise, he co n firmed to me th e existence of a twin-crank H onda V4: " We prefer to keep a d ifferent engine design from 2

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