Numbered 49701 to 52195 (approx). Bolt on seat stays with cam type chainstays for rear wheel adjustment.
WM1x21 (f), WM1x21 with plated rims. Black spokes with NPB nipples. Bolt on rear sprocket.
Plain steel racing type with extra strip steel stay on rear.
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.
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.
Front, 8” assembly from 500cc with steel shoes, and 350cc assembly on the rear with aluminium shoes operated from RHS of machine.
4 speed close ratio gearbox with rocking foot change on LHS of machine. Gearbox gear indicator. Gearbox end cover thicker than standard with no kickstarter. Clutch chainwheel with 40 teeth.
Twin 1 3/8” low level pipes into Rudge ‘can’ type silencers and 5” fishtails.
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.
TT type exhaust pipes. LH brake and RH gearchange.