After legendary Triumph boss Edward Turner retired from his motorcycle factory in 1963, he holed up in a BSA subsidiary, CarBodies Ltd of Coventry, but simply couldn’t keep his hand off his original passion, two wheels. Having entered the hallowed pantheon of Motorcycle Greats with his popular, stylish, and sometimes avant-garde machines from the 1920s onwards, he is best remembered as the man who made a parallel-twin engine look like a twin-exhaust-port single cylinder machine (the 500cc Speed Twin of 1938), which fit snugly into the existing ‘Tiger 90’ single-cylinder chassis. This new combination had magic in name, looks, and performance, and set the tone for the British motorcycle industry for the nearly 50 years.

The chain-driven camshaft drive can be clearly seen on the end of the crankshaft, as well as the shifter gate. [John Woodward]
Turner’s prototype has been restored to running condition by John Woodward, on staff at the National Motorcycle Museum in Birmingham. Many thanks to Mick Duckworth for forwarding these photos and information about the prototype!