This 1974 Triumph 500CC dirt-bike just came to us with the challenge of getting it running. Immediately upon visual inspection, John questioned if it perhaps had a BSA motor in it, as he stated that it looked identical to an old BSA motor that he built for racing in his younger years.
Upon further inspection of the frame you can see that it states “MFD-BY B.S.A. ENGINEERING LTD. FOR COMPETITION AND OFF-ROAD USE ONLY.” As John called it, this is a Triumph motorcycle manufactured by BSA.
Back when John was building this same engine for racing, the customer he built it for was at the Daytona Race Track and seemed to be under-performing by a landslide. Curious what was giving his competitors the advantage, the gentleman began inspecting the other bikes there and noticed that everyone had a spacer plate under the cylinder. He inquired why this was being done, and was provided with the explanation that they installed a longer rod- but left the bore and stroke the same. This allowed them to turn more RPM’s due to the angle of the rod. A clever trick, John performed the same modifications to the engine when the customer returned from Daytona and they saw significant the performance gains it had lacked before.
We believe this beauty still has its original factory paint and are impressed with how nicely taken care of the bike is overall.
We can’t wait to get this one on the bench and hear it run!
