The Model 9 493cc OHV engine has three ball-race main bearings, a roller big-end bearing, dry-sump lubrication and a primary chain enclosed in a cast alloy case and running through an oil bath.

The three-speed gearbox was available in a variety of ratio options, two of which were intended for sidecar applications.

From 1924 through to 1926 the front downtube of the Model 9 frame forked just below the tank to enable the exhaust header pipe from the central exhaust port to pass between the two frame tubes. From 1927, the exhaust port was angled to the left of a single downtube and a similar Model 90, so named because it could reach 90mph (145kph), was introduced with a twin-port cylinder head and the two exhaust pipes passing either side of the front downtube.

Courtesy Motomania

Sunbeam Model 9 1924-1937