Despite Kawasaki’s denial that the bike ever existed, this 250cc S1R prototype was constructed in 1972 (together with a 350cc triple).
Correspondence with riders in Japan has revealed that both bikes were tested at Suzuka but proved to be not competitive against the Yamahas of the time. The factory chose to focus on the H2R project and the two smaller triples were shelved.
This bike was then shipped over to Mack Kambayaski in California to see if he could develop it further. It raced once, at Virginia International Raceway, but was not successful.
Although it was only a prototype for testing, Kawasaki invested quite a bit in the engine. The gearbox is a one off six-speed unit, the crank uses the type of orange-ringed non-spin bearings that are found in the 500 & 750 racers. The dry clutch is also a one off unit. A H1RA ignition is used. The chassis is from a A1RA/F5R.
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