Classic Motorcycle Mechanics - - CLASSIC EVENT -

ack in 1969 the H1 (aka Mach III) cer­tainly was big news. Not the big­gest news be­cause it ar­rived at just the same time as Honda’s CB750 and with­out a doubt a 750-4 trumped a 500-3, at least in terms of mag­a­zine head­lines. How­ever, there was no deny­ing that a 60hp mo­tor in a 174kg chas­sis was a po­tent brew – of­fer­ing a bet­ter power-to-weight ra­tio than the Honda. In fact it blew the Honda off the road – or at least the drag strip, be­ing good for a sub 13-sec­ond quar­ter mile, bet­ter than the CB750 by around half a sec­ond, while match­ing the top end of around 115-120mph. If you could keep it out of the hedges – not an easy task – it was a gi­ant slayer. Kawasaki – who’d only stepped into mo­tor­cy­cle pro­duc­tion se­ri­ously in 1959 (when they es­tab­lished their works at Akashi, then ac­quired ri­val Me­guro) – came to the H1 via the A1 and A7 (that’s the 250cc Samu­rai and 350cc Avenger) twin-cylin­der road­sters. Th­ese two had sim­i­larly been the prover­bial blue­touch pa­per, but un­like the triple were disc-valve mo­tors – as was be­ing used on Kawasaki’s twin­cylin­der then V4 grand prix 125cc road rac­ers. With all the Ja­panese man­u­fac­tur­ers step­ping up the ca­pac­ity cat­e­gories in the late 1960s, the H1 was ef­fec­tively Kawasaki’s first ‘big bike’, or high per­for­mance big bike at least, the ear­lier W1 650cc twin – based on BSA’S 650cc A7 – be­ing a lit­tle, well, flac­cid. But if the W1 was leisurely, the H1 was sim­ply manic. Kawasaki, like Suzuki, had con­sid­ered up­siz­ing their twins to 500cc – and if that had been the case they would have kept the disc-valve in­duc­tion, but their project en­gi­neer, Yukio Ot­suki, also in­ves­ti­gated the triple op­tion – and liked what he saw. With a 120º crank the triple was bet­ter bal­anced than a twin and with three pis­tons the en­gine was pump­ing less torque through each of the cylin­ders which meant a lighter clutch and trans­mis­sion could be used. Of course the lay­out meant for­go­ing the disc-valve in­duc­tion, but even with

Suzuki may have played it safe with its two-stroke range in the late 1960s. But not Kawasaki, the green team went for broke with a suc­ces­sion of fast and fu­ri­ous stro­kers. Their first triple, the H1, took the bis­cuit though. Prop­erly men­tal, you could say.

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