Cycle News - Archive Issues - 1990's

Yet by coupling this with an increase in co mpres sion to 13.5:1 (obtained by skim ming the head and using a thinner head gasket), a ported , flowed and polished cylinder head wit h res haped stock valves an d seats, an Akrapovic exhaust system designed from scratch - including the headers - by the Slovenian pipe wizard, Belgarda's own specia l gearbox with the top four gears altered from stock, and an all-new ignition developed in Italy to allow maximum benefit from engine R&D, Belgarda engine guru Pa o lo Carminati has ext ra ct ed 123 horsep ower at the gearbox at 14,500 rpm from the R6 en gin e at this earl y stage of devel opment. , There's even the option of tailoring (he power delivery to suit a specific cir'cu it, by playin g a ro u nd wit h cam timlng , ign ition curves and the length and ~ h a pe of the bellmo uths for the 37m)11 Keihin semi-flat-s lide carburetors - fitted '\v ith a TPS th rottl e pos it ion sensor which fur ther s harpens engine response. The result is an engi ne that , w hile it ~ea lly likes to rev - the big red shift light on the dash flashes a t 14,000 rpm, with the soft rev-limiter cu tting in at 15,000 rpm to flutt er the en gine - also has a surpri sin g amount of torque, which allows you to s hortshift in places like the last two leftha nd ers leading on to the Misano main straight. Here, you can change up earl y at around 12,000 rpm and grab top gear before cra nking into the tum, allowing you to settle the bike better as you d rive through the fast sweeper hard on the gas, with the revs risin g as you cra nk over onto the shoulder of the tire . i But Carminati's s ki ll has been to deliver an engine that is fast, but forgiving, eager to rev (though the street R6's }5,500 rp m red line is appa rently fictitious; get you r tach dialed in before you believe it ) ye t with strong midrange torque by the standards of the class. "The e ngi ne it se lf is so good as it comes, we onlv have to work on fine tuning it," sa y~ Carm ina ti. "Fill in the bott om of the po wer curve, and buil d on the exce lle nt top end , a nd you have a bike which is both reliable and strong. To uc h w oo d , we n e v er vet lost a n engi ne eit he r on th e dyno 'or a t a rac e track ." 50, the Belga rda R6 pu lls hard from as low as 6000 rp m ou t of the tigh t Misano hairp ins if you really ask it to, driving cleanly to the IS,OOO-rpm rev-lims iter with no ho le in the power delivery. All the while the ratios of the sweetshiftin g ra ce g ea rbox, whose action seems mu ch s moo the r than th e rather harsh s treet R6 transmi ssion, make it easy to keep it revving above the 10,500 rpm power threshold , for ext ra dri ve. Th e l e-va lve engine (still on ly fou r valves per cylinder: Yama ha uses 750cc as their five-va lve thr esh old ) picks up so s tro ng ly in mid range co m pared to a s treet R6, yo u get the impressio n the cra nk has bee n lightened . Of course, this is n ' t th e case s ince Supers port ru les don't allo w that and cou ntless pos t-race tea rdowns hav e confirmed it . Even so, aro und 13,000 rpm, there' s an extra ru sh of rev s. Despite all that, th e engi ne is su r p ris ingly torqu ey a ll through the power curve, while also allow ing you the op tion to sav e a couple of shifts by fluttering the soft rev-lim ite r - like on the ru n between the Quercia right-hander, opposite the Misan o pits, do wn to the first chica ne. It's a magical motor , and the muted howl from the Akra povic pipe makes yo u feel mast er of the Su pe rsport universe - bu t th e potent engine a lso ran very coo l on such a hot day - thanks to the hu ge pair of radiat ors fitted to cool it. Yet all t h is co mes delivered in a good -ha nd ling, sweet-s teering chassis package that a llows th e R6 to cha ng e direction at speed so easily, maki ng it feel mu ch lighter than a Superbike even after being balla sted with some five pou nds of lead to mee t the 367pound class limit. Althou gh th e R6's a rc h it ec tu re is quite different from the YZF600 Thundercat the Belgarda team raced so successfully for so long (including taking Vito Guareschi to the runner -up Wor ld Series s lot in '98), with a 40mm shorter wheelbase yet 60mm longer swingarm, and a much hi gher center of g ra vi ty thanks to the unique triple-stack gea rbox layout, Giu lio Bar d i says they had a pleasan t surprise w h en th ey started work on the new bike. "The stock R6 in street form is very close to the way we finis hed up racing the YZF bv the end of last season," Bardi says. "So ' we haven't changed a lot in se tup th is year, beca u se in terms of chassis geometry, Yamaha have given their street customers a clone of the bike tha t finished second in the Superspor t World Series a yea r ago. We tra nsferr ed our knowledge of the old bi ke to th e new one, and mod ified the bigger 43mm forks wit h the same m ixture of Ohlins and Belgarda parts, the n developed a new Ohlins rear shock to suit the R6' s lo n g er sw i ngarm and differen t rati o. The only real p rob. lern we had in making it hand le o n th e ra ce tra ck wa s hopping at th e ba ck und er b rak in g , ca used mai nl y by a co m bi na tio n of w e igh t tran sfer a nd e ngi ne ine r tia . Bu t some heavy duty th in kin g, and An ders An dersson's help, overca me the problem via in tern al shock design - so the only factor left to ge t over was tire perfo rmance, and we fixed tha t by switchi ng back to Michelin . (Jami e) Whitham won the first race after w e did so , a n d s inc e th en , we'v e always been contenders." I tried the Yamaha set up to suit both Belgarde riders, but Bontempi uses such a hard rear setup on the Ohlins s hock tha t eve n wit h my extra weight aboa rd, it felt very unstabl e putting the power d own hard ou t of a turn, and ner vou s running over bumps. That's becau se he is used to po wersteering on the th rottl e with the back tire from his days racing Su perbikes on Dunlops. His only co mplaint abo ut the R6's handling is that the bike stops mid -tum. "I ca n' t make it w hip round easily a nd fire it up out of the corner," he say s, "but I know this is upersport and there are limi ts to what you can do on trea ded tires! " To show how st iff he runs the suspension, Bontempi uses 5mm more fork preload than teammate Massimo Meregalli , and 4mm more on the rear shock, whi ch al so uses the ha rdest sprin g Ohlins can supply for a Supersport bike . That's stiff: Try to bounce the seat u p and down b y pressin g your body weight on it at rest, and - nothing happens. 5o lid! It's also worth no ting that b oth Belgarda riders drop the forks through a little, unlike thei r American rivals, for example. "We saw this at Laguna Seca, " says Bardi. "But the Americans use Dunlop tires , which are rounder and turn more easi ly. We drop the forks a little to make the flatte r Michelin profil e tum bett er. " Co mpared to the Bontempi R6, Merega lli's se tu p felt much better .bala nced and m ore neutral in handlin g, even thou gh slightly harder than when I' ve tested his YZF600 in the pas t. In th is form , the R6 gave great traction ou t of the Misa no tu rns - aided by the wi d er 5.50-i nch rear wheel, co mpa red to the old YZF • w ith ju st a qu ick flick of its hea d as the fro n t w heel lift ed und er accelera tion, befor e settling do wn quic kly, a nd resuming normal se rvice, and driving hard ou t of the tum with the tire hook ed up, rathe r than sq ui rmi ng a nd moving around on the gas w hen [ tried to do the same thing in Bonternpi mod e. You'll alwa ys get the bik e moving aroun d a lot on trended tires, however good the y a re, but on the Belgarda R6 it all felt totally contro llable, n~ver threaten ing to get out of hand . The fact that a few (a d m itt e d ly ma jor) suspens ion ad justm ents can so alter the character of a Supersport bike, yet dial it in so well to the tastes of two such contrasting riding styles, speaks volumes for the R6's th oroughbred chassis design, which frankly is worthy of a much mo re costly up-marke t motorcycle. Yamaha sells you a lot of bike for the money wit h the R6. Sus pension is the key to Su pe rsport supremacy, and the conventional 43mm Yama ha fork chosen by the R6's creator, Kunih iko Mi wa , fo r t h e ir re duced uns pr ung w eight com pa red to upsided own ones , delivers load s of fro nt end fe el as m od ifie d b y Be lga rda. It a ll ena bles yo u to carry lots of corner spe ed while safe in the knowledge you can feel wha t the front Michelin tire is doing. It' s a great setup, almost as good as a m uch cos tlier race fork, which didn't cha tter at the fron t even w hen the tire started to wear. And 30 la ps at Misano in this heat without losing grip was a tribute to the Michelin customer tires . Th e Yarnaha-s trademark a rch itecture, with its triple-stack gearbo x layout, sho rt engine and long swi ngarm , gives e xcellent tracti on as w ell as lo ts o f weight on the front w heel (52/48 percent), for extra grip in turns - again helping maintain corn er speed safely. But it isn't unstable under heavy brak ing as its R7 Superbike sis ter was when I rode it at the start of the vear. The 300mm carbon Lorraine d iscS fitted to the Belgarda Yamaha, matched to the stock one-piece Sumito mo ca lipe rs w h ich a re now the ben chmark sto ppers' in the Su persport class, give outstanding br aking - sensitive without bei ng gra bby, with lots of bite, ye t controllable modulation. Th e brakes are d efinitely one of the strong poi nts of an alread y impressive bike. "We' re gonna have to start working on it se riou sly now," jokes Giu lio Bardi. "Bu t, se rio us ly, thi s is a bike that w as born well - as goo d for privateers as for privileged teams like ours, becau se it has a pow er ful ye t reliable motor , and a goo d-hand ling chassis that' s respon sive to se tu p. But we're still only climbing the R6 learni ng curve - it's a good bike a lready, but next season onwa rds , it has the potential to be eve n better." CN 27

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