Norton 1933 633 cc sv single (82×120) “ Big Four” frame 56658 engine 56801
The model name “Big Four” was used from 1907 till 1954, when production of all side valve Nortons stopped.
The model was mainly designed as a strong and reliable sidecar machine: in world war one many were supplied to the Russian army, and in world war II the further developed Big Four did excellent service in the British army.
Reliability and fuel economy were keywords for this Norton.
It had the biggest capacity and the lowest compression ratio in the 1933 range( 1:4.5) Gearbox is Norton’s own four speed.