Frame

Numbered 49601 to 52195 (approx). Bolt on seat stays with cam type chainstays for rear wheel adjustment.

Wheels

WM1x21 (f), WM1x21 with plated rims. Black spokes with NPB nipples. Bolt on rear sprocket.

Mudguards

Plain steel racing type with extra strip steel stay on rear.

Tanks

Petrol tank black with single lined panel and 8 bolt fixing. Twin Coventry Movement quick release fillers with front fitted petrol balance pipe. Single or double breather. Single bolt damper arm fixing. Oval or triangular knee grips. Twin brass lever petrol taps. Oil tank mounted on seat tube with twin Coventry Movement quick release fillers, one either side of machine.

Engine

4 valve 249cc with cast iron open valve TT pattern fully radial cylinder head, bolted to the barrel from below. 14mm central plug with oval inlet port. Rear mounted BTH KC1 D6 racing magneto driven at half engine speed. Oil feed to rear of cylinder and camshaft. Webbed crankcases manufactured in RR50 alloy with cast platform for magneto mounting.

Brakes

Front, 8” assembly from 500cc, and 350cc assembly on the rear operated from RHS of machine.

Electrics

None.

Transmission

4 speed close ratio gearbox with rocking foot change on LHS of machine. Gearbox end cover thicker than standard with no kickstarter. Clutch chainwheel with 40 teeth.

Carburetter

Amal 15TT32.

Exhaust system

Twin 1 3/8” low level pipes into Rudge ‘can’ type silencers and 5” fishtails.

Standard Fittings

1” handlebars, central stand, handlebar controlled steering damper and leather fronted toolbox on nearside of machine. Frame with 1 1/4” front downtube. Open ended ‘D’ section forks (500cc TTR pattern with round bump stops). Pressed steel central stand.

Extras

TT type exhaust pipes. LH brake and RH gearchange.

©  Colin Chapple