c1950 J.A.P Speedway 500cc Motorcycle

Description

The history of JAP can be traced back to 1895, when J A Prestwich founded his engineering business in London and in the space of a few short years, began turning out lightweight, high quality engines used in everything from aircraft to motorcycles. Equally well known for his cinema projectors, Prestwich also built complete motorcycles for a brief period, his first unveiled at the 1903 Stanley Show, using a BSA frame with sprung forks and an ohv engine mounted vertically. The range evolved to include both 2.5 and 3.5 horsepower models by 1905 and there was also a three-wheeled variant; the following year saw a new 6 horsepower V-twin and even an in-line triple used in a forecar. However JAP gave up manufacturing motorcycles in 1908 in order to concentrate on suppling others, including Brough Superior, Triumph, Zenith and HRD. The range of proprietary engines ultimately produced by the company was extensive, including both side-valve and advanced overhead-valve designs, with capacities varying from 175cc to 1323cc. An ohv V-twin was successfully developed for racing purposes and the company even patented a desmodromic valve design in 1923. JAP engines were popularly used in speedway racing well into the 1960s and also found their way into racing cars, including those developed for the popular Formula 3 category in the immediate post-war period by the likes of John Cooper. Morgan famously used a JAP engine in their three-wheelers and the company later turned its hand to building components, including the cylinder head for the Lotus Cortina.