Cycle News - Archive Issues - 2000's

a ren't allowed to change the engine stroke in Superbike racing , so have to ho mo logate a bike all over again (complete with IS O-off m inimum run for a compa ny of Ap rilia's size) if you do . It's a n indication of the strength of Ap rilia 's com m itment to the c a use of S upe rbike su c ce s s tha t they d id this . S o wherea s t he s tock 998cc vo lum e -pr oduction e ight-valve RSV IOOO with c hai n -driven DOHC measures 97 x 67.5 mm - its torquey long-stroke a rchitecture, compared to its 98 x 66 mm Ducati/ S uzuki/Honda 90-degree V-twin rivals , ta ilored more towa rds real world road riding - for its raceorientated Mille SP Superbike sister, Aprilia ha s gone to the other extreme an d p rod uced a s hort -stroke 100 x 63.4 mm 9 96cc 'otto valvole' e ngi ne developed in c o nju nc t io n with Cos wo rt h in Br it ai n - with a p o t e nt ia l appetite for revs to deliver the power up h igh that wins Superbike races. Together with th e bigger bor e come s a n in cre as e in valve s ize s , using revised profil e s a nd ca m timing for the chain -driven double o ve rhea d c a m s ha fts per c ylinder - inlets ar e up from 36mm on th e s toc k RSV10 00 to 40 .7mm on th e SP , a n d exhau st s from 32mm to 36.5mm, s et at a flat ter inc lud ed va lv e ang le o f 3 0 deg rees , comp ar ed t o 32 degre e s , and one vers ion of th e fa ctor y ra c e e ng ia lte re d m a s s. Th e lo wer c ra n k driven counte r bal an cer, m e anwhi le , wh ich is fitted to iro n o ut the vibe s of the na rr ow -a ng le V-twin eng ine on the street Mille, is still retained on th e works Superbike , though the road b ike 's seco ndary ba lance shaft m oun ted o n the rea r cyli nder head has been jettisoned , in pursu it of a lit tl e ex t ra p ow er a t th e expe nse of s o me inc re ase d vi b ra tio n . Re vi s e d engine inte rnals are fitted on a n ongoin g b a s is , with Anton ello fi rs t t o employ th em befor e passing th em on to Co rser, thou g h at th is s ta ge th e red a nd matt-b lack Ap rilia is still down on powe r to its m a in rivals , maki ng Corser's feat in turning it into a cons istent race-winne r a ll the more creditable. Wh ile Aprilia cla ims the street SP delivers 14 5 hp at the crank a t 10, 7 00 rp m , a nd God da rd 's p roto ty pe didn 't have a lot m or e tha n th at a t the rear wheel la st season , Co rser's Superb ike no w prod uces a round 165 h p at th e gea rbox , at 11 ,300 rp m over 10 hp less than its Ho n d a o r Ducati V-t win rivals . Aprilia 's exact outpu t varies s lightly from tra ck to track, howe ver, depend ing on the fuel injection ma pping via which the te a m tailors th e pow e r delivery to suit each circuit. But while the bik e struggled to keep up o n faster tracks like Moma a nd Ho ck enh eim , t here 's im p ro ve d m idrang e perfo rm an c e c om p a re d to '99 - Cors er sa ys he ca n d rive o ut of t u rns from 7 - 8000 r p m , a nd th e Aprilia currently runs a 12,000 rpm re v-lim ite r, du e to conc e rns about the extra masses and increased we igh t of (A b ov e) The bike i s trick in every way. The 60-degree V-twin sits in an aluminum twin-spar chassis that i s more adjustable than any other In Wo rld Superbike. (L eft) With T roy Corser at the controls, the Aprilia has w on five races thus f ar In 2000 - more than any other brand. the b igge r p istons on the sh ort -stroke motor compa red for exa m ple to the s maller slug in th e lo nge r -stroke Du c at i eng ine, wh ic h p arad o x ic all y h a s a higher s a fe rev limit - at present. The Mille SP e ngine has sand- c a st a lumi num cra nkc a ses rath er tha n the RSVIO OO ' s di e cast ones, ai med at increasing strength and rig idit y at th e cost of a slig ht hike in we ight, offset by th e m agnes ium side covers - while the cyli nder design is a stiffer closed deck for mat, com pared to the RSV's op en dec k de s ign . Howe ver , the dry s um p e ngi ne 's bottom end de s ign is th e sa me as o n th e stock Mille, with a lightweight exte rn a l s tai nless s teel oil tank low down a nd just forwa rd of th e e n g ine o n t h e left, b ut a n u p ra.t e d lu b ric a t io n sy s te m wit h a se co nd return pu mp , a nd no provision for a n extracta ble 6 -s pee d gearbox as o n some other Superbikes , for fear of reducin g crankcase rigidity with the vertically -spli t engine - the race team has to open t he engi ne to change them . " I t hink t h e cha nce to c h a n g e interna l gear ra tios like on a GP bike is a n important optio n we must study for the fut ure ," s a ys Bern ic ch ia . "For s u re, b e caus e we ha ve a pro b lem with a cceleration at the m oment , we fee l the abs en c e of th is m or e tha n if we had a ve ry torque y bike - we can't close up th e gea rbox to get m ax imum injectors per c ylinde r - one in a For mula I-type externa l loc atio n directly above the intake trumpet , th e o ther positio ned ju st afte r the throttle but terfly . Ap rilia 's o n ly reservations about ph ot ographing th e Corser bike naked are c e nte re d o n the throttle bodies: Go figure . In respon se to Corser 's biggest cri ticism of the bike when he rode it briefly for th e first time last Novem ber in the Valen c ia ra in, Aprili a com pletely redes igned the transm iss ion to d e liv e r ' t h e s lip p e r cl utch tha t was absent from th e bike all last s e ason when Go d d a rd rod e it. Making its d ebut app earance in February p rese a s o n testing in Austra lia , the dr y s lip per cl utc h now fitted - inc orpora t ing a co nvent io nal rea r-whee l c us hdr ive , and adjustable for th e degree of s lip - is quite diffe re nt fro m Aprilia's pa t e n t e d P PC pneumatic sy s t e m e mploy ed on th e street Mille. And it is now prov en to be re liable , s ays Bern icc hia . "T his is a bso lutely c ompu lsory for a V-twin ," he a dm its , "but tho ug h we had it unde r develo p ment in ' 9 9, it ne eded a lot of work to find the right setu p and to make it relia ble . I th ink T ro y is very happy with it no w - it was the improveme nt h e wa nte d m ost to see on the b ik e when h e sig ne d for us ." Als o n e w for th is s ea s o n is the tw in -p ipe Ak rapovic exhaust s ystem, a m ixtu re of t ita n ium and stain less steel s e ction s fitted with carbon ca ns, with t h e f ront cy li n de r' s e x h a u s t he a der intru ding through th e ce nte r of th e not particu larl y la rge, bu t quite d e ep , radiator - the Aprilia engine mu st be quit e t h erm o dy n a m ic a lly r j v e out of importa nt turns, and th is com promises our top speed , because it ta kes lo nger to get th er e . E ven o n a V-twin , it ' s a b s o lut e ly d e s irabl e t o ha v e t h is op tion , s o a ltho ugh it will re quire the bike to be re -ho mo log ate d , beca use it will en tail a m od ified engine ca s t in g , t his is something we must strong ly co nsider in future ." Duca ti teams ha ve be en saying th e same thing for yea rs . T h e SP Superbi k e ' s Cos wo rt hdeveloped c y linder he ads are quite d iffe re n t fr om th e sto c k RSV 1000 d e s ign , with th e larger va lves nec e s si ta ti ng a s in g le c e n tra l s p a rk p lu g ins tea d of tw o, p lus rev is ed porting a nd a s ma lle r com bust io n c ha m ber, wh ich incorpora te s Cosworth' s tradema rk five -a xis mac hini ng pr ocess to o ptimize tur bule nce and cyli nder filling, aided by inle t po rts which for this pu rpose a re quite straig ht. Howe ve r, there 's a lo ng e r intake le ngth com pared to th e roa d b ik e , a im e d a t improvi ng torq ue on t his shorte rstroke mot or. Compared to the s ingle injector/ 5 1m m throttl e b od ies used on th e RSV10 00 a nd Mille SP st reetbike , the Aprilia Superbike 's Nippond en s o E F I runs a fu ellin g p ackag e h om o log a t ed in accorda nc e w ith World Superbike re gu lat ion s via a 50off custo mer ra c e kit , featuring bigger 60 mm th rottle bod ies now with tw in cue I e n e vv s A UGUST 2 ,2000 23

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