AJS Stormer 410cc. 1971.


41. AJS Stormer 410cc


Former Grand Prix rider Vic Eastwood, one of the most respected names in British Moto cross has signed on at AJS as permanent works development rider, and in fact is now the only full works rider the company uses in Europe.

Web 212

Freddie Mayes, Malcolm Davis, Andy Roberton, Chris Horsfield, Brian Goss and Dick Clayton have all come and gone, and Vic has been left to develop the new AJS Grand Prix.

Launched this year the production AJS 410 Stormer is the largest two-stroke scrambler the firm has ever produced. The 410’s actual size is 406cc, and the engine is derived from the original double British Championship winning 250cc machine.

The 250 Stormer, which continues in production into 1972, has bore and stroke dimensions of 68mm x 68mm. The 370 Stormer, the first 500cc Class model, obtained its capacity by being bored out to 83mm. Now this bore size has been retained, but the stroke has been lengthened to 74.5mm.

The engine breathes through a 34mm Amal carburetor, compression ratio is 10.75 to 1 and the ignition is by a flywheel magneto. It is entirely to AJS’s credit that they have declined to enter the verbal horsepower race so popular with other manufacturers. If every moto cross bike pushed out as much power as some factories claim, they would be fast enough to take the front line at Daytona. The trend seems to be to wait for your competitors to quote their figures, and then add some.

AJS on the other hand, are quite confident in stating merely, that their Grand Prix 410 develops comfortably “over 35bhp” at between 3,500 and 7,000 rpm, at the rear wheel.

  Web 213

AJS Stormer 410 test day, Barry Sheene, followed by Fluff Brown

A large diameter spine tube forms the backbone to the frame. Oval in section, the tubes diameter varies from 3.5inches at the steering head to 2.25inches at the tail section. Twin hoops sweep under the engine from the steering head.

 Web 214

Vic Eastwood and Andy Roberton / The Battle of Newbury / 1971 

AJS make their own design of lightweight brakes and front forks. Most moto cross bikes use fibreglass side panels to protect the carburetor and airfilter, but AJS opted for a fabric covering. The new alloy rimmed wheels carry Dunlop knobby tyres of the standard moto cross sizes, of 2.75 x 21inches up front and 4.00 x 18inches on the rear.

In Britain the 410 AJS sells for less than the ever-popular 400 Husqvarna. In addition, AJS spares are far cheaper, for example a 410 piston is a third of the price of the Husky equivalent.

So in Britain the AJS has a big price advantage over the top Continental bikes, by the time its shipped to America, this differential nearly disappears and it has to fight on more or less level terms with the big names from the Continent and Japan.

When you ride it, the first impression is that the handling is accurate and the machine is dependable.

 Web 215

Vic Eastwood AJS Stormer 410 / Newbury 1971

The AJS Stormers front forks suck up the bumps perfectly and the bikes sure footedness shows no tendency to want to jump out of the ruts.

The front is on the heavy side, but this is really no bad thing and many riders prefer it, because it ensures the bike makes positive rear wheel landings from any jump.

The bike also encourages you to take handfulls of thottle coming out of turns, you feel confident that the front wheel is not going to rear up and you feel sure in the knowledge that its going in the direction you chose. The springing on the rear end is too hard however and allows the rear wheel to hop under hard braking, so you may want to have softer springs for hard ground racing.

The brakes themselves though are most impressive, powerful enough to cut speed dramatically if you get into trouble on the way into a turn, but they still offer enough feel to prevent you locking the wheels.

Inside the hubs, AJS fit a seal, which is very much like a massive piston ring. It doesn’t stop water getting in, but this is not so important as the brake tends to dry out dampness anyway. But what it does do is keep out muck and dirt, which helps the brakes work more effectively and also lengthens the brake shoes life.

Web 216

Barry Sheene with his Alloy tanked AJS Stormer 410

The engine lacks some of the brute bottom end torque of other two-stroke moto cross bikes but it doesn’t load up in corners, even if its taken down to really low revs, so its down to the riders style. When the revs rise to the middle and upper end of the scale, it finds its zip and the power feeds in easily without any sudden surges to send the rear wheel sideways, this combined with its handling gives you a well balanced, competitive moto cross machine.

Riders of average build will be fine with its seating position and control layout, the gear lever is a bit high but you can adjust the footpegs to your own needs. Gearshifts can be made without the clutch, and the shift action is perfect.

If you miss a change, it will be your own fault, not the machines, you’ll only have yourself to blame. AJS offer two options for the internal gear ratios. The most common is the close ratio box, but it’s worth noting, that the expert, Vic Eastwood, uses the wide ratio option.

The rear brake lever is neatly tucked out of harms way and is easy to apply. The kickstart lever though can dig into your leg, riders call it “Ajay ankle”, but it has now been covered with a rubber sleeve, on all Stormers, it helps a bit.

For the serious moto cross man who’s moving up, to the 500cc class, the Stormer 410 is well worth a closer examination. AJS have gained some good results with their young rider Doug Grant, they have also smashed the endurance record down the Baja Peninsula, and that’s no minor feat. With Vic Eastwood on board, this machine could be developed into something very special.

 Web 217

AJS Stormer Workshop Poster / 1971

Return to Contents.