AA (M20 & M21) SPECIFICATIONS, PRICE & IMAGES

Bike Features

Make Model:

AA (M20 & M21)
(M21
specifications recorded. Click
here for M20 specifications)

Year:
1937 – 61

Engine:
Four stroke, single cylinder, side valve

Capacity:
591 cc / 36.1 in

Bore x Stroke:

Up to 1938: 85 x 105 mm
After 1938: 
82 x 112 mm

Cooling System:
Air cooled

Compression Ratio:
5.0:1

Oil Capacity:
2.4 L / 5 US pints

Carburetor:
1937-38: Amal 76, 1939-45: Amal 276, 1945 onward: Amal
monobloc

Exhaust:
Single, chrome

Induction:
Aspirated

Ignition :
Magdyno

Battery:
12 V

Starting:
Kick

Max Power:
11 kW / 15 hp @ 4200 rpm

Clutch:
Multi-plate, dry

Transmission  :
4-Speed

Final Drive:
Chain

Frame:
Twin cradle

Front Suspension:

Up to 1947: Girder
After 1947: 
Telefork

Rear Suspension:

Up to 1947: None, spring loaded saddle
After 1947: 
Plunger type

Front Brakes:
Up to 1955: Drum, 7 in

After 1956: 
Drum, 8 in

Rear Brakes:
Drum, 7 in

Wheels:
Steel, laced spokes

Front Tyre:
3.25 x 19 in

Rear Tyre:
3.50 x 19 in

Dimensions:
Length: 
2180 mm / 85.8 m
Width:    
740 mm / 29.1 in

Dry Weight :
167 kg / 369 lbs

Fuel Capacity :
11.4 L / 3 US gal