Ori­gins of the Honda VFR750F

Classic Motorcycle Mechanics - - MIRA FILES -

So poor was the V4 en­gine’s im­age in the mid-eight­ies that Honda was on the verge of aban­don­ing it. The firm’s rep­u­ta­tion for solid re­li­a­bil­ity was in tat­ters fol­low­ing a bun­gled re­sponse to prob­lems that had emerged with its VF750F sports bike that was part of a com­plete range of so­phis­ti­cated liq­uid-cooled 16-valve V4s. Camshaft bear­ings and lobes had been wear­ing pre­ma­turely but Honda failed to solve quickly what was ba­si­cally a sim­ple pro­duc­tion is­sue. Yet the V4 range of­fered im­pres­sive per­for­mance (at a price) and re­flected Honda’s dom­i­nance in road rac­ing: Joey Dunlop had been the owner of the For­mula 1 ti­tle for three years, but this wasn’t enough to com­pen­sate for the con­tempt that the pub­lic had for the V4 en­gine. The UK and Ger­many were lone voices fight­ing for the V4’s rep­u­ta­tion. Honda UK’S Roger Et­cell was sales man­ager at the time: “In 1985 we had an all-day R&D meet­ing in Ger­many and the V4 de­bate took us late into the night when only my­self for the UK and a col­league from Honda Ger­many wanted the V4 to con­tinue! The R&D peo­ple were ready to give up and fo­cus on a new range of in­line fours: the CBR600 and CBR1000F, while other coun­tries (in­clud­ing North Amer­ica) were happy to see the back of the V4! My point was that the V4 con­cept was right and that R&D knew what was wrong and the best way to re­dress the neg­a­tive PR was to pro­duce some­thing 110% bet­ter. In the end R&D went away to de­sign some­thing spe­cial along­side the new in­line mod­els.” The re­sult was re­vealed at a press con­fer­ence dur­ing the Bol d’or 24-hour race in Septem­ber 1985 when an all-new 750cc V4 was un­veiled, the VFR750F. The bike was com­pletely re­designed in ev­ery way ex­cept for its V4 lay­out. Most ob­vi­ous change was the use of a light al­loy beam frame and a much more com­pact ap­pear­ance. But fir­ing up the en­gine re­vealed more sig­nif­i­cant changes had been made by Honda’s en­gi­neers: it sounded more melodic with a me­chan­i­cal ring to the en­gine. Power was up and weight down. And true to its long-term strat­egy, Honda was of­fer­ing a good all­rounder, a sports bike that re­flected its strengths in en­durance rac­ing. None of the re­li­a­bil­ity prob­lems were of­fi­cially men­tioned at the press launch of the VFR750F at Jerez in south­ern Spain in the fol­low­ing Fe­bru­ary of 1986. But it was an im­por­tant ma­chine for Honda, as ex­plained by Isamu Goto, who was manag­ing di­rec­tor of Honda R&D: “We do not think that the racer replica is the proper ap­proach to the su­per sports mo­tor­cy­cle. The aim is not sim­ply to go as fast as pos­si­ble, as it is with a rac­ing ma­chine; as im­por­tant are el­e­ments such as the com­fort of the rid­ing po­si­tion, ease of use, and the fa­cil­ity with which the rider comes to feel at home.” The most im­por­tant fea­ture of the en­gine’s de­sign was that it used gear-driven camshafts – pro­vid­ing that novel sound – as in­tro­duced on the VF1000R two years ear­lier. Honda claimed that with the use of gears, by us­ing two sets of idlers in

each cylin­der bank tak­ing drive di­rect from the cen­tre of the crankshaft, fric­tion losses were cut by al­most a third. Power was raised to a claimed 104bhp at 10,500rpm (up by around 15bhp) by im­proved ex­haust scav­eng­ing and a less-re­stricted in­take sys­tem. Ex­haust scav­eng­ing, and the en­gine’s sound, was im­proved by chang­ing the crankshaft from 360º to a new lay­out with op­posed crank pins (180º) pro­vid­ing even fir­ing in­ter­vals and smoother ex­haust flow. The VFR750F’S beam-style frame weighed much less than the VF750F’S, yet was 50% stiffer. Dry weight of the ma­chine was 199kg. The orig­i­nal VFR750F was an im­por­tant turn­ing point in Honda’s for­tunes. It was an ac­knowl­edge­ment that even Honda could make mis­takes, and deal with them.

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