Offered from The Forshaw Speedway Collection, c.1979 Rotrax-JAP 4 Valve Speedway Racing Motorcycle

Engine no. 4V 78602

• An extremely rare example of the final evolution of one of the greatest engines in the history of speedway
• Well presented condition

The Tottenham factory of J.A. Prestwich have been known as manufacturers of a multitude of engines including the ubiquitous JAP speedway in 1931. Realising that speedway was a highly specialised sport Prestwich gave the sales concession of the engine to Victor Martin and Company Ltd in 1932. Victor Martin produced complete machines based on both Rudge (Lot 498) and Wallis (Lot 503) designs throughout the 1930s. After the war Victor Martin working with Clem Mitchell from Edinburgh developed a frame to meet the new post war demands. The Martin Mitchell lightweight frame was associated with Jack Young's back to back World Final titles in 1951-2. By this time other manufacturers were moving in - Mike Erskine with the Staride and Rotrax (Lot 520). In 1951 Alec Jackson bought the manufacturing rights to the JAP speedway engine as well as the concession to market Rotrax.

The Mk I Rotrax frame used Reynolds 531 tubing in an all-bronze welded construction that was light and strong but with the desired flexibility. The frames were chrome plated by the neighbouring company, Blakes of Gosport. The Rotrax was another epitome of the 1950s speedway machine. However, with competition from Jawa moving in and pushing frame design, Rotrax followed the lead, producing the Mk II in 1969.

George Greenwood succeeded Alec Jackson in 1967 and in 1979 gave the venerable JAP engine it's final development. With the 4 valve revolution now firmly established first with Weslake and Godden with Jawa eventually succumbing to the inevitable tide, Greenwood produced a 4 valve version of the JAP. The JAP engine had reigned supreme for more than thirty years but was now past its sell by date and this 4 valve development was never likely to be too successful. The attempt to produce a 4 valve JAP was a noble effort but very few engines emerged as it was never a popular choice. Today this intriguing engine is a great rarity.

This Mk II Rotrax JAP is a well presented example of an extremely rare example of the final evolution of one of the greatest engines in the history of speedway. Accompanied with a considerable amount of JAP literature, photographs, parts books and adverts concerning the JAP legacy, the mechanical condition is not known and therefore we recommend re-commissioning and/or restoration to a greater or lesser extent.
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