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In 1937, Triumph’s Chief Designer and Managing Director, Edward Turner, unveiled the Triumph 500cc Speed Twin motorcycle at the National Motorcycle Show. Its was a revolutionary design that changed the course of motorcycling from that day onwards, and its engine format still forms the basis of motorcycle engineering today.

In 1937 the Speed Twin was very reasonably priced at just £75. Its engine was a beautifully symmetrical design with camshafts fitted on either side of the barrel enabling more air to pass through the cylinders and over the head. It also had centrally-disposed pushrods in plated tubes and an inside flywheel supported mid-way between the crank journals by a stiff web. The valve-gear was totally enclosed and the camshafts were gear-driven, as was the Magdyno. The 63mm bore and 80mm stroke engine produced 28.5bhp at 600rpm.

The Speed Twin was an instant success. Its performance, smoothness, ease of starting and overall handling impressed the buying public greatly. Soon, most other manufacturers followed this design so as not to be left behind, and although modern day motorcycles would no-doubt completely out-perform it, the origins of their engine designs stem from Edward Turner’s Coventry built 1937 Speed Twin.

Category: Product

Institute: Coventry Transport Museum