Cycle News - Archive Issues - 2000's

"Hariey-Davidson ShippinS." To mte and review a treat road, users ned to create a Harley-Davidson user profile at www.harley- davidson.com, and then link to "Great Roads" page under the "Experience" section. 2Fast has announced that it will b€ startint its track day and performance motorcycle- ridin8 school season a little early this yea( commencint its first event on Wednesdax March 22, at Pacific Raceways in Kent, Wash- in8ton. Additional scheduled 2Fast dates are as follows: Ap.il 19 - Wednesdayt May 17 - Wednesday; Juhe 2lst - Wednesday;ruly 29 - Saturday (Seattle 100): Aug'rst | 6th - Wednesday; and Autust 30 - Wednesday. Motorq,,ciists of all ages, ridinS experience, and riding styles are welcome at 2Fast events. Fo. more in{ormation, visit www.2-rast.org on the lnternet, or email Brian Ofton at brian@2-fast.org or Mark Decross at mark@2-fast.org. MotoGP Tech: The New Honda o o o o a 5 (left) Hondo merhqnics work on Todolnrki Okodo's 2006 nc2l IV. (Righr) The rwingorm on the Hondo hd. chongad. one, though you can clearly see the num- ber of changes that have been made to chante the way the airbox vibiates at cer- tain points of the rev band, and where the airbox is working in harmony with the motor, there is the potential lor as much as lo-percent additional power from gettint this verl, tricky bit oI enSihe tuning ri8ht. ln addition to all the work on the frorf of the chasris, it's eag/ to s€e that the swingarm has also been dreInatically modi- fled, and it now looks as if the last l50mm or so have been slimmed down to flex dif- ferently than the original prototype. lt is dif- ficuh to say whether this new design will flex more or leis, as it depends on what Honda has done at the point where the new section of swin8arm has been welded on, Dependin8 on the aonstruation tech- niques used, it would be possible to make the swingarm stifler the flrst half of its length and weaker at the very back. lt s€ems the science of buildin8 flex in the chassis for Eood grip when the bike is at a hith lean angle is getting quite complicated. It's not iust whether a swingarm flexes enough when the bike is leaned over to rnaintain trip, but precisely how it flexes that mafters. Again, by adopting a longer, slimmer swintarm, Honda is mimicking Yamehts M I larest desitn. Honda isn't sayinS what the horsepow- er levels of the new motor are, but they are cleady extremely serious about win- ning th6 championship in its linal year. Not only is this the linal year of 990cc l,lotocP competition, but both Yamaha and Honda have two riders championships +iece, so lheae is the prize of being rhe most suc- cessful 990cc MotoGP factory to fitht oyer. Clea.ly, Honda is hot lettint anything stand in its way. N.i, Spdrd,rg the chassis and siwintarm to tet it work- ing better, The main chaasis has been revised, with the "Bmo bike" already u.ing a dif- ,erent chassis compared to the ones used since the RC2llV was first launched. lt had geometry and wheelbase changes from the original, but the overall look remained very similar to the first one, This one, however, is clearly difrerent, as the.e's been a m4or change in the rout- ing of the air-inlet tubes. The hole in the side of the twin-spar chassis that wa5 previously filled with an air duct exiting from a ram tube (6king its air from the ouBide and undeEide of the fairing) ha5 be€n partially filled in. A new hole has be€n cut in the chassis closer to the rlder's hands, with tle air now being taken in throuSh a new front fairin8 that Llonda rolled out the final prototype of I lits 2005 bike at the final Sepang test in l'4alaysia last week. With Kyoichi Yoshii, the RC2llV design chief, watching and Tady Okada back in the testint se6t after nearly two years of helping run the HRC Britiih Superbike team, the bike went out for test- in8 on the first day of the three-day test. After that, t was handed over to Nicky Hayden, who went about th€ business of comparinS it to the 2005 model he's been using to this point in the off season. The new RC2l lV is clearly a modified version of the bike lirst s€en back in Autust 2005 at Bmo in the Czech Republi. - now with a powerplafit that has been fufther revised. For the fi.sttime since the debut of the RC2llV engine five years ago, there are mdor - and obvious - chanSes on lhe outside of the engine. Honda clearly undeE(ood lasr year tha(, compared to the Yamaha, its bike was not stable under braking or on the entry into comers. To try to improve is bike, Honda produced the "Bmo test bike" that both Sete GibernaLi and l4ar Biaggi used fo. i'.rst a few laps in the days after the Czech Grand Prix last year. The new blke and its engine and gearbox assembly weae about 8mm shoner, with the clutch lowered a few millimeteB to allow the rearmost shaft in the gearbox to be moved forward slight- ly- We now have photos of the latest ver- sion of the motor that has clearly taken the science of MotoGP racint up another level - but also back neally 30 years. The new engine is resplendent widl a newly finned deep sump, and we haven't seen this much finning on a motorrycle engine oil sump since the last of the l4V i\gusta 500cc four-strokes was retire{ some 30 years ago. The fins are in place to increase the surface area of the sump, and therefore it! cooling abilit, - and this Sives a clear impression that this year's engine is substantially more powerful than last year's version, As you increase an enSine's power output, typically you also increase the ertine's heat output. But that's not all dtat's new, as the engine appars to also have a new clutch. Honda has used the $rne basic design of diaphr-a8m spring slipper clutch since rhe bike was intro- duced, the onry chanSe coming in year tvvo, when a "urrbine" cover was added to th€ pressure phte to diaS in more cooling air The clutch on this prototype, which you ca, see iLrsr in fronc of the rider's leg, appears to have flve coil springs replacinS the diaphragm spring oI the original. lf these are indeed coil springs, then Honda will be mimicking Yamaha's clutch design, which has used the coil-spriht version of slipper-clutch design since the M I's inception. lf they have manaSed to improve the clutch, that will certainly help stabilize the chas.rla, as the throttle is lhut prior to rolling into comers. Honda has also radically modified the swinSarm and chassis fitted to this version. lt will be quite surprising, howev- er, if the final production ver- siom. which we should be see- int in just two weeks' time, look as part-finished as this has its aia-inlet hole right in the center of rhe bike - the point at which the highest air pres- sure pushes. By lnoving its air intake in to the center of the nose of the bike. Honda has ioined the rest of the pit lane in doint so. Thir rerouting not only enhances the ram effect, it also means that the air-intake tobes are slithtly shorter - and the length of the intake tubes is one of the main dimensions that affect th€ way an airbox works. A shorter txbe would typically indicate that the ai.box had been desiSned to harmonize with the motor at a higher rev point. Airboxes can be tuned, because they basically wort iust like a two- stroke expansion-pipe exhaust system. The volume of the airbox, and the size and lenglh of the inlet tubes used, can (Lefi) The new V.five engine. (Below) For

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