AJS 7R/3A motorcycle

FOR THE 1954 JUNIOR TT, race development chief Ike Hatch developed a threevalve version of the 348 cc 7R. As well as changes to the cylinder head and cam box, the bore and stroke dimensions were revised to a near-square 75.5 x 78 mm.

AJS 7R-3A side view
AJS 7R/3A side view

The 7R/3A, or “Triple Knocker,” so called because of its three cam lobes, used the frame and running gear developed for the firm’s Porcupine racers. Hatch went on to develop a shaft and bevel drive for the machine’s triple-camshaft top end, but the project was shelved by the firm’s accountants.

Model:AJS 7R/3A
Capacity:350 cc
Power output:40 bhp (8000 rpm)
Weight:Not known
Top speed:Not known
Country of origin:UK
Specifications AJS 7R/3A


The sparse front view of a racing bike from the early Fifties was not hidden behind a fairing. That was soon to change as aerodynamic “dustbin” fairings covered the front wheel of the bike as well as shielding the rider from the wind.

AJS 7R-3A front view
AJS 7R/3A front view
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