Cycle News - Archive Issues - 1990's

Last year's bike already showed a big improvement over previous Cagivas, which had a brick wall in the power delivery at 12,400 rpm, with zer o ove rrevcapability , and too many lay ers in the powerband to make the bike as rid eable as it need ed to be on all types of circuits. Lawson's '92 bike had improved top-end potential, was quite responsive lower d own and much mor e tractable in Big Bang mode, but needed more revs a t the top end and, especially, better accelera tion. Riding John Kocinski' s bike sho wed th at the engine development team headed by Andrea Go ggi has deliver ed - a nd how! Thi s isn' t a GP race r - it's a tw o-stroke su pe rbike w ith top-end po wer; the kin d of motorcycle you can ac tua lly imagine riding on the s treet, with traffic lights, traff ic ja ms , 'stop signs 'n all. At the top end, Cagiva hasn't just po ked a chink in that wall in th e power deliver y - they've kicked it down. They've done so not only without sacrificing bottom-end power , th ey've actually increased the engine's flexibility to make it even mor e rideable. How else could a pretend racer like me lap Mug el10 fast en ough on the Cagiva to ha ve qualified for the grid in the 500cc GP held there last July? GP 500cc motorcycles have become so powerful - the Cagiva now delivers just" u nd er 180 hp at the gearbox, at 12,700 rpm, compared to just over 170 hp at 11,900 rpm last season - th at th e trick now is how to put tha t power on the ground, even in the Big Bang era w hich gives you a heads tart via the more userfriend ly pow er d elivery of a closed-up firing order. It seems im p robable th at s uc h a motorcycle w ould be called on to deli v. er power as low d own as 6000 rpm, b ut tha t is indeed the case in places like La gu na Seca's fam ous Corkscrew, or Misano's Mickey-Mou se new "bolt-on" sect ion. An d the Cagiva d oes, inde ed, deliver. Dri ving hard en ou gh out o f Mug ello's chicanes on my second lap to unhook the rear tire a t 7000 r p m reminded me I'd better give it another lap to get the Michelin radials really war m before I go t ambitious with the righ t hand. That do ne, I discovered how the power builds so smoothly on the '93 bike: gone are the layers of power from before, with only a decisive extra push from around 9500 r p m remaining to remind you that the cylindrical powervalve has now rotated open - and you 'd better hold on tigh t as the engine rushes on its way to m eet Signore Ma x Revs . You won' t find him at 12,400 rpm like before, nor even a t 12,700 rpm where the engine now makes its peak power. Instead, he's gone on a walkabout - with a Cagiva 500 that tac hs more than 13 grand! He now can be found at 13,200 rp m on a crisp autumn day at Mugello... "Hi, Max, good to meet you - yo u're a long way from horne." This dramatically improved spread of strong, usable power has been achieved by juggling different combinations of exha ust pipe design, the porting of the seven transfer/three exhaust port cylinders, and adjustment of the electronic p owerje t mechanism on the Cagivamodified Mikuni dual-body carburetors, says the Cagi v a GP team's technical director, Riccardo Rosa. "The development of the sealed , pressurized airbox, which first appeared a.t the Austrian GP, was a ke y factor in developing top-end power by improving the engine's breathing," he says. "Once we learned not to over-p ressurize it, and _discovered the optimum pressure through tests in the Pininfarina wind tunnel, we achieved more revs at the top end, as well as better mid-range and (Above) Arguably the trickest-Iooklng of the current crop of 500cc V·four Grand Prix bikes, the Cagiva . features an abundant use of carbon f iber. (Left ) Author Ala n Cathcart, at speed on t he V593. increased outright po wer. It made a big difference." The carbon fiber dueting beneath the sha rk-nosed bodywork, wi th its distinctive mouth waiting to gob ble up stray p rivateer minnows in its way, is the ou tward result of all this ha rd work - bu t it' s, not the whole st or y. Rosa reveale d that the Cagiva is running substantially bigger carburetors than any of the other 500cc GP teams, eve n Honda: 39m m Mikunis at most circui ts, incl u d ing Mugello where I rod e the bike, and 37mrn at a couple others, for increased response out of tight tu rns . That su rely is a key factor in the bike's sudden leap to the front of th e field , for the abili ty to fit such big carbs without sacrificing botto m-e n d response is a technical juggling act that seems improbable - until you rid e the bike and discover ho w much better it performs at eithe r en d of the rev range than before. Proof of this came in the switchback section of Mu gello between the second and third chicanes, a sec tion of tr ack more than ha lf a mile in length descending into the valley in which the circuit is located, then rising out of it again, with four sweeping turns of varying radius. Because the Cagiva is so flexible a nd rideable, I could get on the power hard out of the ch icane withou t the fron t wheel aviating more than a couple of inches o ff the groun d, secure in the knowledge that even in my inexpert hands, twisting the wrist hard with a Big Bang motor was n't going to spit me over the top, which yo u .ris k having happen with a n old -style, 180-d e g r ee firing order. Sure, you have to be prepared for the back wheel to w alk a little under power (es pecia lly w it h the s ta n d a rd Michelin fitted for my test), in cool cond itions, but it digs in well enough to send you va ulting off toward s the next tum in fast-forward mode. Flat-shift up through the gears with the th rottle wide open and your body gl ue d to th e tank, than ks to the CTS speed shifter, and now you're in fourth gear com ing u p to the next off-camber downhill right-hander. It's a mark of the Cagiva's fan tastic spread of power tha t you can ho ld that gea r all the w ay through the next fou r turns, up to the next chicane, riding the throttle like you would on a road bike, letting the revs run up briefly close to 13,000 w hile holding the same gear, befo re you back off for the next tum. Fantastic! . Also notably improved is the bike's accelerati on compared to last year, even though at 281.6 pounds without the fuel tank (as GP weight limits are no w calculated) it's right on the limit, as was last year's bike. The Cagiva may no t have the explosive acceleration of Cr iville's Honda, that I was riding a co u p le o f weeks before, but it does acceler ate a t least as well and probably better than the factory Yamaha I was testing at the same time. The Italian team has not only enhanced the rideability of th e bik e down low, they've also elim inated their major deficiency compared to the Japan- no way will the Cagiva get left for dead out of turns anymore! A ke y fa cto r in imp roving en gine response has been the team's work on electronics, wh ere they' re definitely on a par with the Japa nese teams. As with thei r rivals' bikes, the Cagiva has variable power curv es available via EPROM chip for th e Kokkusan ig n it ion, bu t though they've experimented with Suzuki-type traction control ("more an antiwheelie control," says Rosa ), they're unsure of it s benefits and haven' t retained it . As before, the operation curve of the power-valve is also variable, and is linked via §ensors to eng ine speed and throttle position, further helping to smooth out and extend the po wer delivery low down. But there's more to come in 1994. Rosa admits tha t Cagiva has already tested their latest, ultra-sophisticared, engine-managem e n t s ys te m which incorp orates electronic fuel injection, an d was developed in conjunction with the TAG-McLaren F1 car racing operation - not just on the dyno, either, but in the bike, and even on the track! " We a r e gettin g ve ry satis fyi ng results from this," he says, "and though I think Yamaha may beat us to joining Honda in using EFI in GP racing next season, we won't be far behind - there is definitely a ma jor performance ad vantage to be gained from fuel injection, and we are well on the way to ge tt ing the ben efits of it." ese works teams e ~ . Cf, 0\ rl -.D N Cro ;::l ~ -.. 21

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