AJS 1949 7R Boy Racer 348cc 1 cyl OHC 3406



AJS 1949 7R “Boy Racer” 348 cc OHC Racing Motorcycle frame # 1376 engine # 49/7R 676
Built from 1948 to 1963, Associated Motor Cycles’ AJS 7R – known as the ‘Boy Racer’ – was one of the most successful over-the-counter racing motorcycles of all time. Almost all of Britain’s road-race stars of the 1950s and 1960s rode a 7R at some stage of their careers and the model remains a major force in classic racing today, being highly sought after by competitors and collectors alike.
The 7R was introduced in February 1948 and was designed by Philip Walker, who had also been responsible for the earlier OHC singles. The 7R shared very little with the earlier OHC models; the new 348 cc engine had 74 x 81 bore x stroke dimensions and wide use was made of magnesium castings to keep weight to an absolute minimum. The castings were finished in a highly distinctive gold coloured corrosion inhibiting paint.
Despite the fact that the 7R was not, initially, as powerful as its main rivals – the Velocette KTT and Junior Manx Norton – its robust and simple construction endeared the model to the privateer responsible for his own maintenance. As an example it was possible to remove the rocker box without first having to take the engine out of the frame. Both oil tank and petrol tank – with a capacity of about 21 litres- were made of aluminium. While the duplex loop frame and Teledraulic front fork remained essentially unchanged throughout production, the engine underwent almost continuous revision. With its max power op 32 bhp the early 7R could reach a top speed of about 160 km/h; later versions had a short stroke engine that had an output of over 40 bhp. An interesting book about the Boy Racer’s history and development is Mick Walker’s “The AJS 7R”, published in 2002.
Our Boy Racer has been restored at some time in the past and comes with Smiths 8000 rpm rev counter and quite impressive megaphone exhaust. Both tyres are Dunlop racing types, front 3 x 21 and rear 3.25 x 20.