1927 500cc Calthorpe OHC G.1.

1927 OHC G1 

Appearance As picture 



Engine - 4.98 h.p. 4-stroke over head camshaft, 84mm. x 90mm. bore and stroke, having a capacity of 498c.c., camshaft totally enclosed and automatically lubricated throughout on dry sump principle, oil circulated by double plunger pump of large capacity to all parts of the engine.

Lubrication - Sight feed mechanical mechanical pump on engine shaft, the oil being pressure feed direct to big end.

Carburettor - Binks or AMAC T.T Type.

Tank - 2¼ gallons petrol only, fitted with large quick release filler, enamelled lustre black and lined panel gold, separate oil tank on saddle tube, 1 gallon capacity with auxiliary hand pump incorporated.

Ignition - B.T.H Variable Magneto.

Gearbox - Burman 3-speed, 4-plate clutch and kick starter. Heavy roller chain back and front with shock absorbers on engine shaft and gearbox, Gear ratio close or open at option.

Wheels and Tyres - 26 x 3¼in. W.O., with Dunlop Sports Cord Tyres.

Frame - Weldless steel tubing, heavy type spring girder (round tube) forks.

Brakes - 7in. diameter large internal expanding hub front and rear.

Standard Fittings - Terry patent spring seat, strong steel mudguards with stays, welded steel pannier bag, knee gribs fitted to tank, large plated exhust pipe and silencer.



Available with choice of 3 side cars fitted (click links below to view):

Sports Aluminum Side Car, painted or frosted.

Super Sports Frosted Aluminium Octagonal Side Car, fitted with screen, rear locker and apron.

Super Sports Polished Aluminium Side Car, fitted with upholstred bucket seat, windscreen and separate rear locker.


Additional Information  - (Available to members in downloads section)

  • 1927 Sales Brochure.
  • Advertisements as published in 1927.
  • The Motor Cycle, July 21st, 1927 - Road Test of the 500cc OHC G1 Model.


  • 1927 Sales Brochure.