Scott motorcycle engine, 1919.
© Science Museum / Science & Society Picture Library
Sectioned. This is a 3.75 hp twin two-stroke motorcycle engine based on the Clerk cycle. It was designed by A A Scott in 1909, and used on the Scott motorcycle. The two cylinders which are side-by-side are water-cooled and their pistons move in opposite directions. At a speed of 27 mph the engine made 1,500 revolutions per minute (rpm), and the petrol consumption was between 60 and 70 miles per gallon. The weight of the engine and the carburettor is 57 pounds. Made by the Scott Motor Cycle Co Ltd.