Silk Engineering - The Silk 700S

The Silk 700S

The Silk 700S was launched in 1975 and featured the new engine in a specially designed steel tubular frame made by Spondon Engineering of Derbyshire, who also made the forks, yolks, disc/drum brakes and rotors. Priced at £1,355 it was the most expensive production motorcycle of the time. The 700S continued to be developed at the Darley Abbey works in Derbyshire, along with the SPR Production Racing version. Production was slow, with just two motorcycles a week coming off the production line. Customers could select from five colour schemes – British Racing Green, metallic blue or green, black with gold coachlines or plain red. There was also a Scott special edition in purple and cream – and a special scheme similar to Silk Cut cigarettes, which were popular at the time.

The thermo-syphon cooling system boiled water using engine heat, then fed it back from the radiator in a rubber tube to the engine cases, where it boiled again, removing the need for a water pump.

The Silk Engineering company was taken over by the Kendal-based Furmanite International Group in 1976 who continued production of the Silk 700S and in 1977 it was upgraded to the 700S Mk2, which Silk called the Sabre. Improvements from the Mk 1 included finned cylinder barrels, a redesigned seat, instruments and rear light nacelle. Porting and timing revisions plus a higher compression boosted power to a more respectable 48 hp, but the price continued to rise. In 1978 the 100th Silk motorcycle was produced and production continued until December 1979 when Silk realised they were losing £200 with every motorcycle sold.