BSA A7
“A SPORTS MACHINE in the true tradition… the Star Twin has few equals as a machine for sustained high-speed road work”. So said The Motor Cycle in April 1952, reviewing the latest example of the BSA A7. It is fair to say that The Motor Cycle liked the A7, praising its: “zestful acceleration, excellent road holding, and the ability to devour the miles in unobtrusive fashion”.
That zestful acceleration was provided by a motorcycle with a 92mph top speed and a 16.8 second quarter mile. The glowing 1952 verdict was about the plunger model, a frame design soon destined for the annals of history. Within a few years BSA would drop their rigid and plunger models for a new swingarm equipped frame of a design that would endure for BSA until the end of the 1960s.
The original 495cc twin had an engine originally conceived before the Second World War to take on Triumph’s Speed Twin. This first A7 was a machine in which both Val Page and Edward Turner had some input, though Bert Hopwood was in overall charge of the project. At the end of the war Herbert Perkins and David Munro put the finishing touches to the twin and it was launched to an expectant public in 1946.
The vertical twin had a long-stroke iron head engine. It had a single camshaft at the rear of the block, unlike Triumph’s twin cam arrangement, with the pushrods running in a tunnel at the rear of the two cylinders.
A four-speed one-up appealed for racers to be allowed unadulterated 75-80 octane fuel, as used in aircraft. By comparison modern unleaded is 95 octane.
