The engine is a 84 x 88 based on a 65 degree balance type 50 crank and a B50 84mm piston. The barrel is a 84 mm bore 500T Norton Alfin barrel from Nortons race group back in the 50's The head is an early steel scull cap with a 50mm inlet and 44 mm exhaust with a 34 straight through inlet going to a 34mm Mk2 concentric all gas flowed by SRM. The cam followers, push rods rockers have been lightened. It gave 26 hp at the back wheel going through an AMC gearbox, considering you normally loose a minimum of 6 hp in the gear box, and drive that gives an minimum out put of 32 + hp.

Comprises a 100mm crank with new bigend, balanced at 65% small end to fit the BSA B50 piston, a 84 mm piston and 84 mm ES2 iron barrel that gives 555cc,  Should fit straight into a pre alternator cranks and with a std head.

 with new big end and BSA sized small end

1960's type 50 engine in pieces cleaned and ready for rebuild