AJS Stormer 410cc. Grand Prix. 1971.

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39. AJS Stormer 410cc Grand Prix

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AJS are to produce a batch of 30 hand-built Stormer Grand Prix 410’s, the biggest scrambles two-stroke’s ever marketed by a British manufacturer.

They will also sell 20 hand-built 250’s, named the Championship Replica’s in honour of the success of Malcolm Davis in the 1970 British title series.

The factory has reached a capacity of 410cc on the new Grand Prix by lengthening the stroke of their 370cc engine from 68mm to 74.5mm. The cylinder bore stays at 83mm, so the actual capacity is 406cc, but a one mm oversize piston raises it to 414cc.

Both the 410 Grand Prix and the 250 Championship Replica’s share certain improvements and modifications.

The up-and-over exhaust system of the production machines is replaced by a new unit, which passes beneath the engine.

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AJS Stormer 410cc Grand Prix / Thruxton Comp Shop / 1971

“It means that only one right angle bend is needed in the pipe, and it gives an increase in torque,” said Nor-Vil chief designer Peter Inchley.

Frames will be formed of bronze-welded Reynolds 531 tubing and polished alloy fuel tanks will replace the standard glass fibre component, although the shape is similar.

Other improvements include alloy rims, high tensile handlebars, skimmed hubs, nylon lined control cables, and also the cylinder barrels are painted black.

“These special bikes will be taken from the factory at Wolverhampton to our Norton Villiers Performance Shop, stripped, bored and then rebuilt by the people who build the works scramblers at Andover.”

“Each engine will be put on the test bed and it will not be passed unless it exceeds our minimum power requirement, the 410 should give five bhp more than a 370, with a considerable increase in torque.”

 

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AJS Stormer 410cc Grand Prix Advertising / 1971

The factory hopes that Andy Roberton and Malcolm Davis will race the bike, named the 410 Grand Prix, for the first time at the BBC Grandstand International scramble on February 13th (MCN 6TH January 1971).

Vic Eastwood, one of the most respected names in British moto cross, has joined AJS as a development engineer and works rider.

The surprise move comes only weeks after the departure of Peter Inchley and their British riders, Andy Roberton who has gone to ride for BSA, and Malcolm Davis who has returned to Bultaco (MCN 24TH February 1971).

Eastwood, aged 29, has raced works Husqvarnas for three years. He previously rode for BSA and Matchless.

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 Vic Eastwood AJS Stormer 410cc / Thruxton / 1971

He won admiration for his fight back from a crippling injury in 1968, when he smashed his kneecap, he has been a professional freelance scrambler since he quit his permanent job with the former AMC factory team at Plumstead.

He said, “My job is not necessarily to win races, but to develop the new AJS 410 Grand Prix, through to production.”

Eastwood made his AJS debut in the Belgian International on his Stormer 250 on Sunday, he retired from the first race with engine trouble, but managed to fixed it for the second race were he managed to still come fifth, even after falling off.

He will contest the British Championships, some Continental meetings, and an autumn series in America later this year on the production prototype for the 410cc Stormer.

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AJS Stormer 410cc production version / 1971

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