AJS Stormer: history, specs, pictures

The AJS Stormer Y4250Mk 2 was a single cylinder, two-stroke standard produced by AJS in 1974. Claimed horsepower was 24.41 HP (18.2 KW) @ 7000 RPM.

AJS Stormer
Also called Stormer Y4250Mk 2, Stormer Y4 250 Mk 2
Production 1974
single cylinder, two-stroke
Bore / Stroke 68.0mm x 68.0mm
Horsepower 24.41 HP (18.2 KW) @ 7000RPM
Fuel System carburetor. amal 32mm concentric
Ignition flywheel magneto
Transmission Gear box: 4-speed

Final Drive: chain

Clutch: wet plate diaphram
Suspension Front: telescopic forks
Brakes Front: expanding brake (drum brake)
Rear: expanding brake (drum brake)
Front Tire 2.75-21
Rear Tire 4.00-18
Wheelbase 55.51 inches (1410 mm)
Seat Height 30.0 inches (762 mm)
Weight 229.94 pounds (104.3 Kg) (dry),
Fuel Capacity 2.0 Gallon (7.57 Liters)
Manuals Service Manual


The engine was a air cooled single cylinder, two-stroke. A 68.0mm bore x 68.0mm stroke result in a displacement of just 247.0 cubic centimeters. Fuel was supplied via a port control.


The bike has a 4-speed transmission. Power was moderated via the wet plate diaphram.


It came with a 2.75-21 front tire and a 4.00-18 rear tire. Stopping was achieved via expanding brake (drum brake) in the front and a expanding brake (drum brake) in the rear. The Stormer Y4250Mk 2 was fitted with a 2.0 Gallon (7.57 Liters) fuel tank. The bike weighed just 229.94 pounds (104.3 Kg). The wheelbase was 55.51 inches (1410 mm) long.