Frame

Numbered 58076 to 61400 (approx). Integral seat stays with cam type chainstays for rear wheel adjustment.

Wheels

WM1x21 (f), WM2x20 (r). Rear, QD with taper roller bearings. Chrome rims. Black spokes with NPB nipples. Rear sprocket integral with brake drum on LHS.

Mudguards

Plain inverted U section, unvalanced. Rear with detachable main section. Front & rear with flared ends.

Tanks

‘Aero’ type petrol tank painted with lined panels with Enots reserve tap. Single central CEE-ESS type filler with rear fitted petrol balance pipe. Two bolt damper arm fixing. . Large cut aways underneath both sides to clear rocker box.

Engine

Numbered U1601 to U2300 (approx) - 4 valve 499cc with aluminium bronze enclosed valve cylinder head (with 7 bolt fixing rocker box), parallel inlet valves and radial exhaust. 14mm central plug. BTH KD1 D4 magneto and DM3G dynamo. No oil feed to rear of cylinder.

Brakes

8” front and 7.5” rear, coupled with aluminium shoes.

Electrics

Miller 8” headlamp with No 832 8-0-8 'Lighthouse' ammeter and 35E rear lamp. HF180 Clearhooter electric horn with Lucas LU76204 horn push. No stop light as standard.

Transmission

4 speed gearbox with foot change on RHS. Aluminium oil bath chaincase with ‘R’ on dome and no separate filler on shock absorber dome.

Carburetter

Amal type 29/146  with Binks twist grip control. Original settings: Main jet 150, slide 29/5, needle jet 109, needle position 3. Smiths Petroflex fuel line.

Exhaust system

Twin 1 3/4” low-level downpipes into barrel silencers and plain tailpipes.

Standard Fittings

120MPH speedometer. Pillion pad. Mechanism shield, battery cover, licence holder, cast central stand with lifting handle. 7/8” handlebars with long front brake lever. Single toolbox fitted to RHS of machine. Steering damper and handwheel operated fork shock absorber. Lycett 6B pillion pad. Round tubed forks. THAPEX tyre inflator. RH chainstay valence. Cover to front engine plates.

Extras

Upswept exhaust pipes.

Maintenance Data

  1. Magneto Advance BTDC - 12-14mm (39 to 42 degrees)
  2. Plug gap 0.012" to 0.015"
  3. Contact breaker gap 0.012"
  4. Tappet clearance (cold) -inlet, NIL, Exhaust 0.004"
  5. Piston ring gap 0.012"
  6. Oil capacity 1/2 gallon

©  Colin Chapple