Frame

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

Wheels

WM1x21 (f), WM2x20 (r). with chrome rims. Black spokes with NPB nipples.

Mudguards

Racing type with detachable rear tail section.

Tanks

Petrol tank, black with gold lining. Twin Coventry movement fillers with front fitted petrol balance pipe. Single bolt damper arm fixing and 8 bolt tank fixing. Twin brass lever petrol taps. Oil tank mounted on rear frame tube with 2 Coventry Movement fillers, one either side of machine.

Engine

4 valve 349cc/499cc with cast iron TT type open valve cylinder head, parallel inlet valves (350cc radial) and radial exhaust. 14mm central plug (both) and oval inlet port (350cc only). BTH racing magneto. Webbed drive side crankcase (8) and a single web under the timing cover. Oil feed to rear of cylinder. Plain alloy rocker cover

Brakes

8” front and rear, coupled with steel shoes. RHS foot operated.

Transmission

4 speed close ratio  TT replica type gearbox with foot change on LHS using rocking pedal.

Carburetter

Amal racing type 10TT32. 1 3/32” (350cc) or 1 5/32” (500cc).

Exhaust system

Twin 1 1/2” low-level downpipes into Rudge ‘can’ type silencers and 6” fishtails.

Standard Fittings

1” TT pattern handlebars with Bowden single cable handlebar controlled damper and folded type clutch and inverted levers. Single high level leather fronted toolbox fitted to offside of machine. Pressed steel central stand. Open ended ‘D’ section forks with rubber buffers to rear of fork bridge.

©  Colin Chapple