Frame

Numbered 36443 to 42995 (approx). Bolt on seat stays with drawback type chainstays for rear wheel adjustment.

Wheels

WM2x19 (f), WM2x19 (r). interchangeable with black enamelled rims. Black spokes with NPB nipples. Bolt on rear sprocket.

Mudguards

Inverted 6” U section, unvalanced, front and rear. Rear with detachable tail section.

Tanks

Petrol/oil tank black with gold lined panels. Twin Westwood type fillers with front fitted petrol balance pipe. Single bolt damper arm fixing. Brass lever petrol tap.

Engine

Numbered 1 to 5100 (approx) - 4 valve 499cc with cast iron open valve cylinder head, parallel inlet valves and parallel exhaust. Rockers carried on cast pillars. 18mm side plug. Forward mounted type F 6V ML Maglita or round ML magneto. Round based cylinder barrel and webbed drive side crankcase. Oil feed to rear of cylinder. Timing side crankcase with ‘Rudge Whitworth’ cast in. (note that early crankcases did not have the ‘Rudge Whitworth’ cast in). Cast alloy oblong rocker cover with ‘R-W’ cast in.

Brakes

8” front and rear, coupled with steel shoes.

Electrics (optional)

Miller 7” headlamp with No 74E 6-0-6 'Lighthouse' ammeter  and 34E rear lamp.

Transmission

4 speed gearbox with hand change on RHS of tank. Steel primary chain cover. ‘Rudge Whitworth’ cast into gearbox quadrant cover.

Carburetter

Amal type 6/113 with Amal 2 lever or optional twist grip control. Original settings: main jet 140, slide 6/4, needle jet 106, needle position 2. Chrome plated copper fuel pipe. Note that other sources quote the carb as 6/141 but contemporary pictures (e.g. Newnes) do NOT bear this out. Fitted with flame trap (M2853).

Exhaust system

Twin 1 3/4” low-level downpipes into Rudge ‘can’ type silencers and 6” fishtails.

Standard Fittings

Rear carrier (at no extra charge), 1” handlebars with folded type inverted levers and steering damper. Single toolbox fitted to nearside of machine opposite the battery carrier. Open ended ‘D’ section forks.

Extras

Chromium plated tank with black or maroon panels. Nickel plated tank with black or maroon top and side panels. Maroon panelled tank and mudguards. Bonniksen trip/non trip internal drive speedometer. Time speed meter. WM2x21” or WM3x19” wheels.

©  Colin Chapple