How good was this beautiful little racer built by Associated Motor Cycles? Very good indeed: It was in production and winning trophies from 1948 to 1963. Known as the “Boy Racer”, the 7R won three successive Junior Isle of Man TT races, from 1961 to 1963. It was powered (occasionally underpowered, if truth be known) by a 350cc four stroke single, and designed to combat the all-conquering multi-cylinder Italian motorcycles. Which it did, very effectively, in the hands of racers like Ted Havens.
A new design by Phil Walker, the chain-driven overhead camshaft 7R had the history of the pre-war AJS ‘cammy’ singles behind it. Initially, the 7R was not quite as powerful as its competitors, producing 32 bhp (24 kW) at 7500 rpm. The duplex frame and Teledraulic front forks remained relatively unchanged during production, while the engine had a number of changes. The included valve angle was progressively narrowed, and the crankshaft strengthened. In 1956 the engine dimensions changed from the original long-stroke 74 x 81 mm to the ‘squarer’ 75.5 x 78 mm. The AMC gearbox replaced the older Burman unit in 1958.
However, it is wrong to think of the 7R as a copy of the KTT – it is a generation further advanced. The 7R engine castings were fabricated in electron to save weight – and then anodized gold, not for aesthetic reasons but to protect the easily oxidized magnesium alloy from corrosion.
The frame was a modern, all welded, swinging arm design and the powerful brakes were also cast in electron. Overall, the AJS weighed in at a creditable 136kgs (a shade under 300lbs) and, with 30bhp being available at the back wheel, was both competitive and reliable.
The 7R was campaigned by the factory team and in 1950 Les Graham won the Swiss Grand Prix. This was to be an aberrant result since the AJS was always outclassed at the highest level by the factory Moto Guzzis and Nortons. By contrast, the 7R delighted in its sobriquet “The Boys’ Racer”: a bike for the ordinary racer to ride competitively.
The 1957 AJS 7R 350 cc, with 75.5 mm bore and 78 mm stroke, gave 38.5 bhp (28.7 kW) at 7600-7800 rpm, and weighed 285 lb (129 kg). The top speed was 180-190 km/h (115-120 mph). AMC withdrew from the world of works, and one-off, road racing at the end of the 1954, with the death of Ike Hatch, and in the face of fierce competition from the other European bikes.
After this AJS made a production version of the standard two valve AJS 7R, for privateers and a 500 cc version, badged as a Matchless G50 was also sold. By the end of production in 1963 the two valve OHC AJS 7R engine made over 40 bhp (30 kW). Swedish rider Bill Nilsson converted an AJS 7R road racing machine into a motocross bike and rode it to win the inaugural F.I.M. 500cc Motocross World Championship held in 1957. AJS 7Rs won the 1961, 62 and 63 Junior Manx Grand Prix races and came second in 1966.