This was a development of the E type motorcycle engine into a stationary power unit. Engine production started in 1926 and continued until December 1938. With a capacity of 169cc and rated at 1.75 hp at 1800rpm, this engine was intended as a replacement for the original D type engine. The engine retained the lever starting mechanism of the D type, and was fitted with a large brass Solex type MV carburettor and a front mounted direct driven BTH type M1 magneto. Cooling air was provided by vanes on the flywheel and directed around the cylinder with a cast aluminium cowling. Around 700 S type engines were made.
