1923 2 ½ h.p. "Calthorpe Two-Stroke" Two-Speed

1923 2 stroke gearbox

Appearance As picture



Engine - 2 ½ h.p. PECO, 67mm. bore x 69mm. stroke having a capacity of 243c.c. Two stroke of the three port type. Heavy Phosphor Bronze Bearings of large dimensions. Roller bearing to big end of connecting rod.

Carburetter - Mills, single lever.

Ignition - High-tension variable C.A.V Magneto, handle bar control.

Tank - 1 ½ gallons petrol, 1 quart oil.

Lubrication - "Patent and perfect system" (No oil mixed with petrol), through a sight drip feed Lubricator.

Transmission - Burman 2-speed Gearbox, 3-plate Clutch and Kick Starter, mounted on a neat but stong bracket. ¾in. belt from gearbox pulley to rear belt rim.

Frame - Weldless steel tubing, all vital parts reinforced, Patent Girder, spring forks.

Brakes - Foot pedal operated Block on Belt Rim, powerful Bowden front brake.

Wheels - 24in. x 2 ¼ in. Dunlop Beaded Edge Studded tyres, oil retaining dust and weather proof hubs.

Standard Fittings - Patent Spring Pan seat, rear stand, carrier, strong wide mudguards, Pannier Bag with tools.



Available with 3-speed gearbox, rear hub brake, and all chain drive for extra cost.


Additional Information - (Available to members in downloads section)

  • 1923 Sales Brochures. (2-Stroke Lightweights, Blackburne & Lightweight Combination Models)
  • The Motor Cycle, Nov. 30th, 1922 - The Olympia Show Report Artice.
  • The Motor Cycle, Nov. 23rd, 1922 - Mills Carburetter Advertisement.


  • 1923 Sales Brochures.