Cycle News - Archive Issues - 1990's

made th e established field of tubularfr amed Suz uki and Yam aha twost rok es look very old-fashioned , boasting as it did an adva nce d monocoque cha ssis which was a lm os t a car-style stressed skin affair, sin ce th e fairing flanks were th e frame; a n d p ropheti c " in verte d " front fork s. The engine ma y have been th e mo st radical fo ur-stroke ever built, a n d (u n less you know d ifferent) was th e o n ly reciprocating en gine not to have rou nd p is to n s i n stea d th ey wer e fla t-sided o va ls, des ig ned to mak e room fo r paired row s o f four-val ves in pe nt -ro ofed co mb u stion cham bers, mak ing a n unriva lled eigh t valves per cyli n der. T hese pi sto n s requ ired a pa ir o f co n nec ting ro ds to keep th em level, leadi ng o ne spy who sp otted th e cranksha ft to assume tha t th e engi ne wa s in fact a V-B. Back to th e Fift ies: Duke had kn own Io ra long time th a t th e racing fu tu re la y with multi-cylinder engines . H e joined Giler a , a nd won th ree more 500cc class ch am p io n sh ips on the fas t fours. Before th e ad vent of th e tw o-strokes, a n d the urgent need LO ge t more power , it seems in retro spect th at elabora te four-strok es were built a s much for reasons of co ncep t a nd per sonal en joyrnent - a lt hough doubtless it didn ' t seem th at wa y a t th e time. No manufact urer exp lored th e various possibilities LO the ex ten t of MOLO Guzzi. H aving doubled up th eir suecessfu l 250 single in a wide-angl e (120degree) 500 of ra ce el eg an ce (a n d co n s ide ra b le s u cc ess) , the y soon espoused eng ineeri ng co m p lexity in the quest LO catch up with th e rnultis. T heir four-cyl inder was unique in disposing th e cra n kshaft longitudina lly . T he 1953 ma chine won its first race, but thereafter was di sappo inting - but G uzzi had somethingTar more e x tra va g a n t on th e d rawing boards . . . bike racing's fir st a nd last V-B. The V- B presaged modern twin cra n ksha ft design, an d was th us really a pair of straig h t fours, on a co m mo n cra n kcase and d isposed a t 90 degrees. In its first inca rna tio n , it p roduced 60 bhp a t 12,000 rpm , a lo ng with a so u n d o f m an if old co mp lexi ty , m ixi n g sh rie ks a nd grow ls with in a throbbi ng how l. Its best result ca me in 1957, by when power o u tp u t had clim bed to 80 b hp , when it p laced fourt h in th e Isle o f Man TT, a n d it is certa in tha t th e mach in e ha d no t yet reac hed its fu ll potentia l, for it proved a hand ful to ge t th e awesome but fin icky bea st runn in g rig ht. T he grea test prob lem . by far was in the su p p ly o f fu el - th e Guzz i u sed ei g h t tin y car b u re to rs in terloc ked ina ccessibl y wi th in th e vee, with necessaril y sma ll floa t cha mbers. Along wi th p roblems of vibration, it was d ifficu It even to keep th em topped up for long , a nd the V-8 never we n t ver y fa r wi thou t skipping a bea t. After 1957, the Ita lia n ma nu facturers p u lled o ut of racing, aft er a sq ua bble wi th the FIM co ncerning p la nned techn ica l lim itat io n s. All excep t for MV Agusta , wh o broke th e ge ntlem an s ' agreemen t ·a n d ca rr ie d o n , succeedi ng to a n u nrivalled 17 yea rs o f straight do m in a tion o f the 500cc class. The la c k o f serious opposit ion (Nort on was sti ll p lugg in g away wi th th eir singles) may devalue th is achievement, a n d mean t that MV was ab le LO pursu e a rela tive ly leisurel y develo p ment co u rse wi th th eir twin -earn fours - but th e MV fir e engi nes remai ne d su perb exa m p les o f tech no logy, a nd rem a ined unbea ten whe n no less a foe than Honda eventuall y came a lo n g. They were in every way classic fou rstroke engin es, with tw in ca ms ha fts sp ro u ting p roudl y a top th e cylinde r heads, a nd two va lves pe r cylinder. Ea rly MVs us ed sha ft drive, switch ing to a cha in in 1952 wi th out entirely banishing th e handling p robl em s that were to persist for man y years. T hey wer e always lovel y m achines. . The Ital ians rema ined fa ithful LO a train o f strai gh t-cu t gears running up between th e middle cylin de rs to drive the ca m sha fts, a dd in g an extra rattling sh riek LO th e general a nd mellifluous caco p ho n y. One aspect of th e engines th at rem ains u nique wa s wh at mi ght be ter med th e " Q D " (q u ickly deta chabl e) cra n ksha ft. Ra ther than locating th e ro ller-b earing cra n ks ha fts direct ly within th e ca sin gs, .the MV attached th e cran k webs directly to the cyl inder b lock , wh ich co u ld th en be lo wered into (or lifted o u t o f) th e wet- sump ca s i n gs without disturbin g th e installation. MV wa s eventually for ced to accelerate developm ent in th e mid-60s, when th ey produ ced a .th o ro ug h ly updated three-cylinder screamer which soo n acq u ired fo ur va lves pe r cy linder; a nd for th eir swa n so ng in 1973 a n d 1974 they produced a fin al four: It goes w ithout say ing th at th e p ressure ca me from j a pan, from tw ostro kes a n d from H onda , upon whom it fell LO fight th e last rea rg uard fo urstroke battles. T he j apanese gia nt d id so a t fir st with fa lteri ng steps, with a low- key visit to the Isle o f Ma n TT in 1959; bu t as they gai ned in d ust rial stre ngth they p ro d uce d a n even bo lde r a n d more prolific variety of adve nt uro us (if not a ct ua lly in n ov at i ve ) d esign s th a t reach ed apotheosis with their screamin g 20,000-p lu s rpm five-cyl inder 125 a n d six-cylin der 250 a nd 350, a n d cu lmi na ted in th e N R500 mentioned abo ve. H onda was fighting on tw o fro n ts - agai nst a rising tide o f tw o -strokes in the sma ller classes, a nd agai ns t the esta b lis hed MV fo ur-stro ke do mina nce in th e 500cc class. Th e ba il ie in th e 350, 250, 125 a nd (f ro m 1962 ) th e 50c c cl a sses w a s p ro ba b ly the mo st in teres ti ng a nd ferti le pe rio d tec h ni ca lly th a t we sha ll ever know. Two-strokes were making g rea t s t rides i n d ev e lo pm en t a s designers real ized how to h arness th eir reso na ting frequ en cies to improve power . Simu lta neous ly. MZ's Wa lter Kaa den wa s p erfecting asymm etric ind uc tio n by means o f dis c val ves, a nd t he p re do m inately s i n g le-cy l i n der fo ur-stro kes - MVs, desmodromic (th ree-ca m) Du ca ris, Ma LO G uzzis , FB Mo nd ia ls, MOlO Mo rin is, Ben ell is et a l - were al ready under pressure. T he n Ya maha a p peared o n the scene , a nd Su zuki , who usefu ll y acq u ired MZ's di sc-va lve technol ogy via Ernst Deg ner, who defected fro m Eas t Germa nv in 1961. H ~n d a ' s resp on se carried revs , The four-cylinder 250cc Benelli, cylinder number s and p iston speeds to unprecedented heights, as the everi mp ro vin g tw o- s tro k es ran th e design er s LO th e li mi t, fitted from th e start wit h four va lves per cylin der, th e o n ly o p tio n was to reduce th e size o f th e pi stons, a nd th ei r rate of improvement was powered by ma ssive investments as th ei r ea rl y twins gr ew LO u se fou r , fiv e a nd ulti m atel y six tiny cylinder s. In 1960, th eir sing le cylin de r 50cc racer p roduced 10 horsepo wer at 14,000 rpm: two years lat er th eir l25cG four revved LO 16,000, a n d used a n eigh t-speed gea rbo x; in 1965 the 125, ridden b y Luigi Taveri ,' h ad fiv e cylinders and had bro ach ed th e 20,000 rp m mark. T h e 250 grew from four cy lin ders to six in 1964 (the 350s were en la rged versions o f 297cc), a nd th e clas s saw The 1940 three-cyli nder Moto Guzzi. fierce fig h ti ng w ith Ya maha , whose two -stro kes elided up as twin -cra n k V4s n ot u n lik e thei r mod ern YZR s. In those da ys, whe n H onda entered, they d id n't a lways wi n . T hey had particul a r troub le wi th Suzuki in the 50cc class, with o nly one rider's title; a nd with Yamaha as we ll in th e 125s. Bu t th ey held the wh ip hand over Yamah a in the 250cc class, a nd had a strai g ht run of wins from 1962 to 1967 in th e 350cc class. Honda co u ld be eq ua lly proud o f th eir manufacturers' title record , with a peak in 1965 of victory in a ll five solo classes. But the ulti ma te honor - a n individual rider 's 500cc class Litle - el uded th em . IL took a p hi losophi cal reversa l and a sw itch to two-strokes for H o nda fin all y to win the 500cc crown , when Fr eddie Spencer na rr o w ly def eated Ken n y Ro berts in 1983. T he ir fourstroke 500s (th ey may ha ve built ot her engines , bu t they never race d th em ) h ad the horsepower , bu t they seemed constitutionally una b le to cu re their wa ywa rd h a nd lin g , a n d eve n th e legendary Mik e H ai lwood co u ld never su m m o n th e seas o n -lo ng resou rce s required totopple MV Agusta. Then in 1969 th e FIM stepped in aga in , o nce aga in with a set of restrictive legi sla tio n to - ca ll a halt to th e sp ira ll in g techn ical co m plex it y. The new technical ru les mostl y rem ain in force to th is da y - noi se regulations that p u nish ed th e deep- bellowed fourst ro ke h o wl er s: restric tio n s to th e number o f cyli nders (to a maxi m um of fo ur cylinders for the 500cc class, two for the 250/ 350 a nd I25cc); a nd a lim it of six gears, a mong o ther th in gs. T he j a panese factori es wi th drew in p rotest jus t as th e Ita lians had done 13 yea rs ea rlier. T his marked th e dawn o f a new era in the sma lle r classes, in wh ich p riva teers an d European tiddl er ma n u facturers a li ke rejoiced, wi th p rod uc tio n (or sem i-p ro d uc tio n) Yamahas ta ki n g ove r th e 250s, a nd Kriedler a nd Derbi (a mon g o thers ) poki ng their heads u p in 50 and I25cc classes. By then , the bat tle had been won. In terms o f the curre nt legislation, and wi thou t th e help of turboc ha rgi ng or su percha rgi ng, four-strokes co u ld never ma tch two-stro kes for horsepower. Even so, it too k a bit o f time to s in k in . In the larger classes, two-stro ke en gineers were still developing th e technol ogy a nd metallurgy that would a llow th e revs th ey need ed with bigger p istons, a n d MV Agusta rem ained to figh t a rea rguard ac tio n. T he Italians h ung on to co ntro l in th e 350cc class until 1973, a nd -in th e 500cc class for .o n e yea r longer. But it was only a matter of time, as th eir longtime rider Giacomo Agostini knew well, and he swi tched to Ya maha to w in a fi nal 500cc crown in 1975. It wa s the first suc cess for a tw o-stroke in wh at FIM Pr esident j os Vaessen rightly ca ll s " T he Kings' C las s" , a nd th ey have held co ntro l ever sin ce. Mea sured by rider s ' titl es , twostrokes had ta ken co nt ro l o f racin g step by step, starti ng th e do m ino effect in th e 50cc class in 1966, since the n no four-stroke ever wo n it again. T he sa me landmark ca me in 1967 in th e 125cc cla ss, th ree years la ter in th e 250cc cla ss, a nd the no w-defu nct 350cc class in 1974. T he la st bastions - the sideca rs a nd th e 500cc class fell LO the in va ders in 1975. And no th in g co u ld ever bri ng th em back but the mos t .a rtificia l ind uceme nts, or radica l new ru les th a t wou ld cha rge the fun damenta l way o f raci n g engines by cu bic ·cap acity. A tragic p ost-scri p t: the la st fo urstroke to win a 250cc ti tle was Kel Carru thers' Ben elli in 1969. The sa me machi nes wer e still sol dieri ng o n in 1973, a lt hough the task was ba sicall y h op el e ss - d ated two- ca m fou rcy lin der screa mers agains t the everim p ro vin g Yama ha s; a nd a t Mama in th e 250cc G P o ne of them spi lled its guts o ut on the racing line whe n' it b lew up. In the subsequent 350 rac e, th ere was a mass pile- up on the first la p o n o ne o f the circui t's magni ficent (p roch ica ne) fas t bend s. Am o ng a number of serio us injuries, two rid ers were kill ed . . . p opular Itali an R e nz o Pa so lini and rising Fi nnish Ya maha sta r lam a Saarinen. Saa rine n wa s rat ed as a road-racing genius , a tal en tlarge eno ug h to have made history. H e wa s a lready making an impact on th e 50Dec cla ss with th e Yamaha, a nd had hi s caree r not been en ded so prem aturel y, might h ave defea ted the MV Agustas sooner. A trag ic wa ste o f a bri llia nt ride r a nd a doom- laden sto ry that is as fu ll of relevance tod ay as it was then. Four-strokes ma y ha ve been sad ly missed from GP racing, but nobody wa nts to see any more oil-spill crashes. CI 23

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