AJS 7R Pictures

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Built by Associated Motor Cycles, the AJS 7R was a racing bike built from 1948 to 1963. it proved highly successful for the AMC factory as a racer, and was also used as a privateer racer from 1954 onwards. The AJS 7R was also known as the "Boy Racer".

AJS 7R Specifications

The AJS 7R was designed by Phil Walker. The engine was a single cylinder, with 348cc capacity and had a single overhead cam, which was chain-driven. It was capable of producing 32 bhp at 7,500 rpm. This power output was less than that of the competitors' bikes at the time.

The original AJS 7R had a duplex frame and Teledraulic forks, which were a huge improvement over earlier girder forks. The frame specs remained mostly unchanged during the motorcycle's production run, with changes made to the engine.

The crankshaft was strengthened and the included valve angle was narrowed. The piston stroke was made shorter in 1956, from 74 x 81 mm, to 75.5 x 78 mm. The original Burman gearbox was replaced in 1958 by an AMC unit.

The AJS 7R3

In 1951, Ike Hatch, the development engineer on the AJS models, designed the three valve head version of the original 7R engine. It had the shorter 75.5 x 78 mm piston stroke. The power output increased to 36 bhp.

The improvements were implemented to make the bike more competitive against Italian multi-cylinder racers. The first year of racing produced good results, but in the following year, the relative performance was not as good.

Further improvements were thus made in 1954. The works manager, Jack Williams modified the frame of the bike, lowering it, and changed the tuning of the engine. It then produced 40 bhp at 7,800 rpm. The changes paid off, with the victories at the first two rounds of the World Championship, and first place at the Isle of Man TT.

Racing Performance

The 1961, 62 and 63 Junior Manx TT championships were won by the AJS 7R. The 1957 AJS 7R had a 350cc engine, with an output of 38.5 bhp at 7,800 rpm, and a top speed of 120 mph.

Due to increased competition from European racers, and the death of Ike Hatch, AMC withdrew from racing in 1954. AJS continued producing racing bikes for privateers, in the form of modified
AJS 7R's, with the standard two-valve configuration.

The 500cc version had the Matchless G50 badge, and was also sold to privateers. By 1963, when production ended, the AJS 7R was capable of producing 40 bhp.

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