Velocette Motorcycles Dohc Works 1938-1950
Velocette made very few overhead-camshaft 500cc racing singles, the first of which was produced in 1933 with a single-overhead cam with a ‘dog kennel’ cambox, a bronze cylinder head and an iron barrel.
The second ‘dog kennel’ bike had an all alloy engine numbered 5001 and was placed third in the Isle of Man TT before winning the Ulster Grand Prix in 1934. It was then sent to the New Zealand distributor, Bill White, who used it to win the NZ Beach Championship in 1935. It was later raced very successful in NZ by several riders including Len Perry, who rode it to many wins between 1938 and 1950. The third ‘dog kennel’ bike, with engine 5002, was used by Stanley Woods on a successful tour of Australia in 1936. The factory designation for these machines was ‘MT-’ followed by the engine number.
Engines 5003, 5004 and 5005 were manufactured in 1937 and mounted in sprung frames similar to that of the then current Mark 8 KTT production model. They featured large fins on the cylinder head and barrels, and larger crankcase and other castings. They were raced as factory entries during the 1937, 1938 and 1939 seasons with New Zealander, Rod Coleman, as one of the works riders. MT-5003 was well placed in Isle of Man and other races in the late 1930s and was purchased by Rod Coleman in 1949 and used by him in the 1949/50 racing season in New Zealand. Rod later sold it but bought it back ten years later as a burned out wreck. He restored it and it is now in the British Motorcycling Museum in Birmingham.
In 1949, two double-overhead camshaft engines, 5006 and 5007, were produced. Ernie Lyons was placed third and Reggie Armstrong sixth in the Isle of Man TT. The engines had a larger bevel gear housing to accommodate larger bearings and a second oil pump to return oil from the cambox and bevel chamber. Unfortunately, both engines were destroyed in later racing incidents but in 1985 Rod Coleman gained access to all the casting patterns in the UK needed to remanufacture the DOHC engines. An engine was produced complete with correct magnesium castings for the crankcase and all other castings except for the cylinder head and barrel, which were made to factory specifications. With the resulting engine and period gearbox and clutch, a complete replica of one of the 1949 DOHC factory racers was created.