112 MPH BSA M20
As well as being painstakingly restored by enthusiasts to accurate wartime specification, the M20 has also been developed by specialists for speed trials. A 1938 BSA M20 ridden by Bill Jenkins from Dallas achieved a top speed of 108 mph at Bonneville Salt Flats making it the fastest M20 for this venue in the world. The original side-valve engine was extensively modified and fuelled with nitrous oxide. The intake port fed by the carburetor, originally horizontal, was re-drilled at a steep angle into the cylinder casting so it pointed up at the underside of the intake valve. The motorcycle did however retain the long BSA prop stand that hinged under the seat and clipped to the rear mudguard when not in use — so it looked like a stock M20. In October 1995 an M20 fitted with a BSA Gold Star crankshaft sprocket and running on a 95% methanol / 5% acetone mix ridden by Pat Jeal achieved a terminal speed of 112 mph at the disused airfield of RAF Elvington, Yorkshire.
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