Cycle News - Archive Issues - 1990's

retains the radial va lve con fig uratio n borrowe d from Ferrari's F-I car engines (both the older V-12 motor and the new V-I O ra ced by Irvine an d Schumacher this season ha ve suc h a valve layou t), with each of the four valves per cylinder se t a t d ifferent an gles, rather th an in more co nvent io nal p arallel p ai rs, and operate d d irectl y by conical camsha fts specially mad e in Italy. . '; T his is tech no log ica lly no t very eas y," admi ts An drea Goggi. "And we did ha ve some problems earlier m aking it work well, but now i t's okay. Ferr ari na ve p ro ved that the superior cylinder filling and improved 'swi rl you get from radial valves does deliver increased performance, an d this has been confirmed in our dyn o tests. It' s a big plus." r The Cagi va's valves are set at a very flat total included angle to each other of just 20.5 degrees, and are "simi lar in size to a Suzuki or Kawasaki," sa ys Goggi. Figure mayb e 30mm inl et s an d 24m m exh au sts, thou gh the retention of a central camsh aft drive won' t allow su ch a straight hit at the in let po rts as if the cam ch a in were off to one si d e as on the newer-design Kawasaki and Suzuki . To permit such a narrow valve ang le, Cagi va h as b orrow ed one more id ea from Ferrari, w hich is to drive the cam cha in not d irectly off the cran k, but off a half-time p ini on above the cra n kshaft. This b oth n arrow s th e sweep of the cliain ru n and shortens it. . Ho w e ve r, the ob v io us questio n rem ains to be asked : Given that Massimo Bordi' s team in th e Ducat i factory h as been resp onsible for th e va rio us red esigns of the F4 engine over the past five yea rs, and that Ferrari experimented with Ducati-st yle desmodrorn ic va lve gear on their V-12 six years ago (Riccardo' Rosa was again coincident ally one of the developme nt engineers on th is fantastically intricate design, com p lete with n o less th an 96 o peni ng a n d closi ng rockers), d id Ca giva ex periment with p ositive va lve op eratio n on th eir 750? Andrea Goggi shifts in his seat and starts to loo k a little un comfortable, as well as excited at the same time. "No, we never tried a desmo cylinder head on the F4," he says, "but I have to admit that pneumatic valve op eration like Ferrari, Renault, Mercedes and all th e leading F-1 cars use now ad ays is in ou r plans for the future on the Superbike version. We plan to follow Ducati's lead in offering our customers di fferent levels of specification on the production F4, which is relatively easy to do with fuel injection, mainly by altering the EPROM chip . Our philosophy for the production street bike will be different from, say Suzu ki, who made a hard-nosed rac er for th e street tn at is sim I a Su erbike with Ii hts. (Left) Ducati World Superblke rider Pier-Francesco Chill put this F4 tes t mule through its paces at Mugello last year, though neither the twins par frame design nor fairing will be used In production. (Below) Though there Is little Indication as to what the bodywork will look like - excep t good , as It Is being designed by Massimo Tamburinl, the man respons ible for the 916 - the frame s!J~u ld look something like this. f (Below) After trying quite a number of unorthodox engine desig ns, Caglva finally settled on a fairly conventiona l specification for their production in-line four. Cylinder-head deta ils and a radically s hort stroke still set the powerplant apart from anyth ing else you'll find on two wheels. The F4 Strada will be a well-rounded, ridable sports bike peaking at around 13,000 rpm. Massimo Ta m burini co u ldn' t believe it when he tested the prototype on the highway becau se he said he'd never ridden a four-cylinder bike that ha d the same kin d of ridability and torque as a Ducati V-twin. But we will offer an SP version, still for the street but capable of be in g turned into a very co mpeti tive racer, as well as a Corsa Superbike version in both customer an d factory gu ise. And for that, I think we'll end up us ing pneumatic valve op erat ion eve n tua lly, espec ially as our target engine speed for the F4 race engine is 15,500-16,000 rpm, and for an ything ab ove that, yo u need posi tive valve control." , , In any case, bo th th e SP and Corsa versions will have a dry clut ch a n d extractable gear cluster for the six-speed gearbox, p ermittin g internal rati os on the gear cluster. to be swapped GP-style w ithout splitting th e en gin e or e ven removing it from the chassis. The b iggest change s in ce Pi e rFrancesco Ch ili tested the delta-b oxfram ed F4 development ha ck fitted with 500 GP bodywork at Mugello last summer was to con vert the d ry-sump engine fa more conventional wet-sump lubrication. Wh y? "Two reasons," says Goggi. "Spa ce and dynamics. T he F4 engine is very small for a 750cc four, especia lly one with an ultra-sh ort stroke. It mea su res 73.8 x 43.8mm w hereas th e new ZX7R Kawasaki, which is the most over- square of current Japa nese Superbikes, is 73 x 44 .7mm . Our 750 h as th e same stroke as the Kawasaki 600, but has the same wi dth across the crankcases as their 750, and is narrower across th e cylin de r head . This very compact engine design means we can build a sm all bike for its class, which togeth er with th e , steep downdra ft of th e cylinder head , gives problems of packaging . There really isn' t any room for an oil tank, becau se the fuel tank will be taking up the space .reserved for it. Converting the design to wet sump reso lved th is problem. "Th e second reason for the cha nge was tha t we found that if you w ant to make a good dry-sump motor, you must separate the gearbo x and crankshaft oil volumes so that you can push to get a vac u um where yo u reall y need it, like they do in F-1. Obtaining a low air pressure throughout a dry-sump en gine, to reduce pumping horsep ower losses, is very har d, and the figu res delivered in our dyn o tests w ere not so low as to justify sticking with the dry-sump con figuration. 50 we redesign ed it, and now the engine is very close to its p roducti on fo rm, giv ing g oo d h ors ep ower and exceptional rid ability ." Though no confirmed output figures , are avail able, the F4 is understood to be deliv ering ju st ove r 130 bhp in st ree t form with air cleaners, but without prop- . er silencing, running on 11.8:1 compressio n an d unleaded gas. Target for th e race ver sion is 160 bhp "to start with." This high-tech engine is replete with av an t-garde materials and lead ing-edge hardware that is mostly F-1 sourced, like the plug-top coils (each sp arkp lu g cap inco rpo rates the coil for that cylinder), h igh-pres sure fu el pump and semiphased single-pickup EFt with two injectio ns pe r cycle. Thi s engine, however, will not be used in th e twin -spar allo y cha ssis clothed in cast-off 500 GP bod ywork u sed on the Chili test prot ot ype. Goggi says this was only built to allow the team to mo ve on-track de velopment ahead in terms of d ata acqu isition and to fin alize su ch critical factors as radiator size, oil int ercooler and so on , pending arrival of Tamburini's definitive chassis design (with the right kind of head lights, of course!) . Tamburini's design will definitely be a tubular-steel space frame, but using load bearing cas t-aluminum co m ponen ts which w ill creat e a composite chassis in the same way as a Segale design does . But the essential design will be the Cag iva /Ducal'l family's tra de mark iubol are form at, sa ys Clau di o Castig lio ni. "This is an Italian motorcycle, and in the sam e way as the engine design features innovative engineering unlike anything yet made in Japan, so ou r chassis technology mu st be distinct from anyone else's," he declares. "It was difficult to combine a space frame with our four-cylinder engine design, but we did it, and Tamburini the artis t will clothe it in fresh, exciting bod ywork that will befit this most avan t-garde .of four-cylinde r motorcycles." Exp ect th e ch assi s to also feature a cast-magnesium (on the Cors a/SP; aluminum o n th e Str ad a ) si ng le -si ded monobraccia swingarm like on th e 916 Duca ti , e speciall y as Ca gi va h as declared its pl ans to ch ase th e World Endurance title with the new bike. They are particularly interested in victory on th e Jap anes e m anufa cture rs ' home ground in the Suzuka 8-Hour. 50, Cologne in October - a new beginning for Cagiva ? "Yes, for all of us in Cagiva, it will be the start of a new chapter, " sa y s Goggi. "We s to p p e d twostroke GP racing with a heavy heart, but a page was turned, and then we sta rted working 100 percent on the four-stroke, which we realize is so very important for Cagiva's future. People must sto p thinkin g of Cagiva as making only mopeds and 125 roadsters and a few four- stroke singles . They ha ve to start thinking of Cagiva as a big-bike manufacturer, and the wa y to do this is to make something th at wins .respect on the race track as well as in the showroom. That's our goal with the F4, an d none of us who worked 'on m aking our 500 GP bik e capable of winning races against the Japanese factory tea ms will be satisfied until we ha ve achieved th e same thi ng in Superbike racin g. And, some ho w we'll manage to do this. I kn ow we will. " l~ 31

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