Cycle News - Archive Issues - 1990's

RACERTEsr Paolo Casali's Belgarda SOA Yamaha YZF750 Superbike increases midran ge engine perform ance . Wait for othe rs to follow su it with a similar syste m , especiall y if p owerbands narro w in th e pursu it of race-winn in g ho rsep ower in the future. But with 120 bhp on tap at the gearbox at just 10,000 rpm, th e Ru sso YZF engi ne in its ' 94 g u is e alread y ha s a wid e s p rea d o f power. It's a good investment for next se as o n, when Yamaha get s s e rio us about winning the World title . And th a t' s definitely goi ng to happen. Lots of people like to .think the 20valve Yamaha motor is past its se ll-by date in World Superbike terms, but after Casoli ' s performance on this bike in 1994 - with relatively little practice h e was right on the pac e from the sta rt - I reckon th ey 'd better r eth ink thi s. In choosing the Belgarde team to run their works effo rt for them, Yamaha have also made a wise decision, for this is a squ ad with a mission , and the rig ht resources at last to achie ve it. If Edwards o r Casoli - or even Nagai, if he can calm d own a little w i tho u t los in g hi s u n d oubt e d speed - aren ' t frequ ent visitors to the ro strum ne xt seaso n, I'll go w ithou t pasta for a week. List en, if yo u knew h o w good th e lasagne was in the ristorante round th e co mer from th e Bel, garda race sho p, you' d kn ow that was a se rio us sacrifice. Bu t I' m no t worried: Yamah a will do it in-'95 - the Ita lia n 1::\ Way. (Above left) Rear suspension features an Ohlins shock and special rising-rate linkage. In search of tract ion, the specially fabricated aluminum swingarm is 30mm shorter than on the streetgoing vers ion of the VZF. Traction is especially good out of slow comers . (Above right) Like the rear suspension, the 46mm inverted forks are made by Ohlins . Offset was redu ce d this year, slowing the steering somewhat but add ing stability and making the bike more friendly on tum -in. (Right) Feeding the highly deve loped 2o-valve powerp lant is a ban k of 39mm Keihin carburetors. At Mugello, they were fitted with variable length inta ke trumpets that s mooth power de livery. Above 10,000 rpm the trumpets contract by 30mm over a 2000 rpm range to help produce the 158 bhp the eng ine Is capable of. A a p its h ard o n in fou rth gear. Th e-fro n t w he el pops in the air, the bars flap in yo u r hands, and yo u will you rself to h old it wid e open whil e tryin g to st raig hten up and fly right. Unlike Russell's Kawas ak i, w hich did the sa me thing at the same pla ce on the track, the Yama ha pulled th e sa m e stunt at o the r points on th e circu it, wh er e the lack of sufficie nt suspens ion respon se due to too s ti ff a sp ring meant the Yamah a liked to wheelie a Jot. I'd like to try it in Lucchia ri mod e with a longer s w inga rm and so fte r rear shock se tt ings - bet it wou ld be quicker, as well as easier to rid e. N o su ch compl aints about the engine: Beppe's baby delivers the goods. Power comes in strongly just under 9000 rpm, and the delivery is much more linea r th an on last ye ar's bike, pr esumabl y thanks to th at hea vier crank and other mod s. This means th at there isn' t a sudden ru sh o f engine a ccel era tion a ny m o re w he n th e tach ne ed le h it s th e 12,000-rpm m ark: Inst ead, th e p ower de livery is s moothed o u t, with w h a t feels like more power ava ilable a ll th e way through the five-figu re ran ge. With the ext ra ridabi lity this gives you, it' s a pity the rear sus pens ion wasn 't se t up for the best, but the Yamaha is still surprising ly handy coming on and off the th rottle, wi th immediate response from the m otor and a well-chosen set of kit gearbox rati os h elp ing to ma ximi z e d rive ou t of turns. A speed -shifte r was fitted to the bike for th e firs t time thi s season, made by Ru sso himself, and after half an hour spent using it, I can onl y sa y he o ug h t e 20 to s ta r t marketin g it for sale - th e change is excellent, very .light and crisp yet preci se and th ere isn 't th e harsh acti on yo u ge t fro m m an y other system s. Nor is it so sensitive tha t yo u end up sh ifti ng o r cu tting out the ig niti o n when yo u didn' t mean to. A veritable bull 's-eye: Maybe Yamaha mig ht like to bu y th e syste m fro m him and fit it to their street YZF. Anoth er piece of Russo trickery was mi ssing fro m the bike I rode, because th e team is still ex perimenting with it after using it for jus t one race at Mugel10. They d id hav e it fitted to, the spare bike at Phillip Island, thou gh , and that's Beppe's own system of vari able length carb tru mpets, similar to the sys tem Ferrari has been using in F-1 for the pa st sea son and wh ich Du cati experimen ted with last ye ar - before se tti ng it aside until th ey can redesign it. Th e rea son this happened is that the Ducati sys tem was a mechanical one, whe reas the Belga rda Yamaha ve rsio n is electronic, con- . trolled by the ignition and th us capable of bein g reprogrammed to ope ra te over any rpm ran ge yo u wish. Th e ad vantage of course is that you can op timize carburetion, with th e trumpets at maxim um length up to 10,000 rp m, then contract. ing by 30mm ove r a 2000 rpm ran ge up to 12,000 rpm, powered by an electric motor m ounted above th.e gea rbox. From there to th e 14,200 rp m rev -limiter, th ey stay sho rt, before extend ing themsel ves ag ai n wh en th e revs drop for a slow tum. The result is defini tely advantageous, says Beppe, because it smooths out the power delivery even fu rther, and also , . , . SDA ,1IIIIIIa.,IPl50 Sttpet6IIce ~ Engine Dimensions C8paehy Output Compression ratio Carburetlon Ignition Gearbox Clutch Wa ter-cooled dohc four-eylinder transveIse in-linefour -stroke with five valves percylinder and central chain camshaft drive 72 x 46mm 749cc 158bhp at 13,800 rpm (at gearboX) 13 .2:1 4 x 39mm Keihin flat-slide Digital electronic COl (non-programmable) 6-speed Muttiplate dry(8 metaV9 friction) Chassis Aluminum twin-spar Deltabox Suspension Front 46mm Ohlinsinverted telescopic for1ls Rear .... . . . . •. ... . . . Fabricated aluminum swingann with rising-rate linkage and single 0hIins shock Head angle 24 degrees Trail 98mm Wheelbase .: 1410mm Weight 352 pounds with wa ter/oil. no fuel Weight distribution fir . . 53/47% Brakes Front 2 x 292mni Brembo carbon discs w~h four-pistonBrembo calipers Rear 192mm Yamaha steel disc with two-piston Yamaha caliper Wheelsllires 12/60-17 Michelin radial on3.50-ln. Marchesini wheel Front Rear 18167-17 Michelin radial on 6.00-in. Marchesini wheel Top speed 181 mph (Hockenheim) • Year of manufac:tla'e . . 1993 Owner Tearn Belgarda SDA Yarnaha. Lemo, I1aIy

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