The 490cc CS1 (Camshaft Senior Model 1) was introduced in 1927 and achieved immediate success at the Manx Senior TT with Alec Bennett taking laurels eight minutes ahead of the next machine. Stanley Woods, on another CS1, set a new lap record at 70.99mph The maximum recorded speed during the IOM Senior TT was 93mph (150kph).

Walter Moore's cammy engine drove through a Sturmey-Archer three-speed gearbox, a saddle tank appeared on the new machines for the first time, and a cradle frame with Webb works achieved superior road-holding. Braking was also enhanced with Royal-Enfield 8" hubs front and rear.

Production machines appeared later that year, and were first marketed in 1928 with a top speed of 85 mph.

Moore was enticed away by NSU and a German version of his OHC engine soon appeared on their machines. The CS1 remained in production until late 1929 when a new version was released.

Courtesy New Zealand Classic Motorcycles

Norton CS1