Especially one that does 108mph. I got these pics from the gadget engineer. I have read that this bike ran on nitrous oxide and was ridden by Bill Jenkins at Bonneville salt flats. Also there is another M20 nocking around that achieved a top speed of 112mph ridden by one Pat Jeal.
1938 BSA M20: With a top speed of over 108 mph recorded at Bonneville this has to be the fastest M20 in the world. If you consider that in stock condition, this bike had a top speed of no more than 55 mph, then this is the equivalent of making an unfaired Triumph 650 top 200 mph. Although the flat head, side-valve engine was extensively modified and enhanced with nitrous oxide this bike still retained both factory kick-stand and a typically-British prop stand that hinged under the seat and clipped to the rear fender stay when not in use. One really trick feature was the revised intake port that was drilled at a steep angle up into the block so that the carburetor bore pointed directly at the underside of the intake valve."