Photo ou archives : F-M. Dumas
350 7R Works Racer -1938
Only two of these splendid machines were built, to allow AJS works riders Bob Foster and George Rowley to race in the 350 class while Matchless (both companies were then part of the Associated Motor Cycles group) competed in the 500cc category with its supercharged water-cooled, four-cylinder machines designed to contend with BMW and Gilera.
7R or Not 7R?
Some motorcycle historians contend that the prewar racing AJS 350s should correctly be called "R7" and that only the post-WWII "Boy Racer" is really the 7R. That's just splitting hairs. The few racing AJS 350s sold to private owners from 1931 on were officially catalogued as the Model 7R. The two works bikes built in 1938 were a logical development of these "straight-from-the-crate" chain-driven ohc singles.
These machines were really very special. They had light-alloy cylinder heads with screwed-in valve seats, aluminum cylinders with iron liners, heavily-ribbed magnesium crankcases and heavily reinforced crankshafts. Their gearboxes were made by Burman to AJS specifications and had magnesium covers. In an attempt to improve roadholding, AJS used - for the first time - a rear suspension with a sturdy triangulated swing arm in combination with plunger dampers fixed to the frame, on similar lines to the 1937 DKW layout. These 7R Works Racers failed to live up to expectations in the Isle of Man but had more success at Brooklands, where speed and good suspension counted for more than roadholding alone.
Engine: 348cc (74x81mm) air-cooled single-cylinder four-stroke
Power Rating: 28 hp @ 6800 rpm
Valves: chain-driven overhead-camshaft
Fuel System: Amal racing carburettor
Transmission: Burman-AJS 4-speed, chain final drive
Suspension: Webb girder forks (front); swing arm with plunger springs (rear)
Brakes: drum (front & rear); magnesium front hub
Wheels: 3.00x21 inch (front); 3.25x20 inch (rear)
Weight: 335 lb
Maximum Speed: 106 mph
The direct ancestor of the immortal post-WWII A]S "Boy Racer" was this very special 350cc 7R Works Racer built in 1938.