The 1929 REX Dirt-Track racer that was available in both 350cc and 500cc models.
Both models used J.A.P. engines, the 350cc model having a bore of 70x90mm whilst the 500cc engines had a bore of 80x99mm. Both models were also of 4-valve ohc type.
Looking more like the standard type of machine was the 1930 Rex-Acme that came fitted with a Python engine. This machine was ridden with a great deal of success by Squib Burton before becoming available to the public and sold at Pounds80 in Petrol-benzol trim.
NOTE: The "Python" was in fact the name given to a Rudge-Ulster Dirt Track special engine.