From the estate of the late Jeff Clew
1929 Velocette 415cc Speedway Model Re-creation
Engine no. KDT 149
Among the rarest of all speedway (or dirt track) racing motorcycles is the Velocette KDT, only 21 of which were made by Veloce Ltd in 1929. Developed with the clandestine assistance of Jack Parker, then contracted to BSA, Veloces speedway model handled well but suffered a disadvantage because at 415cc its engine capacity was 85cc less than that of its rivals. (Veloce did not make a 500cc model at that time).
The project to recreate this speedway Velocette began over 40 years ago when Jeff Clew swapped a bundle of magazines for a completely dismantled 415cc KDT engine belonging to former VMCC President, the late Eric Thompson. It had been fitted to a speedway model that left the factory on 29th September 1929 destined for Hubert Bert Clayton of Huddersfield to race at Halifaxs Thrum Hall track.
Bearing the number prefix KDT, the engine is basically an over-bored 348cc KTT unit, the cylinder bore having been opened up to 80mm from its original 74mm. It runs on methanol and has a compression ratio of 10.25:1, and does not need the KTT's cam box oil return pump because speedway races were (and still are) of short duration. The combined petrol/oil tank necessitates long oil lines to the pump in the crankcase as the engine has a dry sump lubrication system. The gearbox is a Velocette three-speed type of the same year, acting as a countershaft to permit the use of a clutch. It has no kick-starter or gear change mechanism. Currently, the box is locked in second gear for demonstrations other than on a track. Changing the gear ratio to suit track sizes and conditions is facilitated by Velocettes trademark outboard final drive sprocket.
Jeff installed the reassembled engine in a 1929 Velocette KSS chassis at first and ran the bike in Vintage sprints before undertaking the re-creation. Finding an original dirt track frame proved impossible so a copy was made by grass track champion, Lew Coffin. Lew modified the frame of a 1927 KSS using a drawing, originally published in the 7th August 1929 edition of Motor Cycling, which was supplied by the late Bob Currie. Note the additional but unusual dog leg lower chain stays and the way in which the saddle tube slants backwards to the rear of the gearbox mount. Additional plates under the gearbox give the rear engine plates greater rigidity.
Owned and built by Jeff Clew, the Velo was last ridden by him with other Vintage speedway bikes to celebrate Exeter Speedways 60th Anniversary in 1989. Fitted temporarily with braked wheels, it was also ridden in a Vintage motorcycle parade at Mallory Park by Jack Parker of Belle Vue Speedway fame, who had assisted Harold Willis, Veloces Development Engineer, with the design of the speedway models cycle parts.
Previously on display at the Haynes International Motor Museum in Sparkford, Somerset, this wonderful re-creation of a rare Velocette competition model is offered with a substantial quantity of correspondence, various period photographs (including some of Bert Clayton on KDT 149), assorted press cuttings, frame geometry drawings and a copy of Jeff Clews own article about the machine published in Off Road Review (issue 92).