Open main menu


The BSA B50 MX was a air-cooled, four-stroke, single cylinder, OHV Enduro motorcycle produced by BSA in 1971. Max torque was 28.03 ft/lbs (38.0 Nm) @ 5000 RPM. Claimed horsepower was 34.06 HP (25.4 KW) @ 6200 RPM.

Production 1971
Class Enduro
air-cooled, four-stroke, single cylinder, OHV
Bore / Stroke 83.8mm x 83.8mm
Compression ratio 10.0:1
Horsepower 34.06 HP (25.4 KW) @ 6200RPM
Torque 28.03 ft/lbs (38.0 Nm) @ 5000RPM
Transmission Gear box: 4-speed, manual

Final Drive: chain

Clutch: wet multi-disc, manual
Suspension Front: telescopic fork
Rear: dual shocks
Brakes Front: drum
Rear: drum
Front Tire 3.25 x 18
Rear Tire 3.5 x 18
Wheelbase 54.02 inches (1372 mm)
Length 85.0 inches (2159 mm)
Width 29.02 inches (737 mm)
Seat Height 32.01 inches (813 mm)
Weight 140.0 kg (wet)
Manuals Service Manual



A 83.8mm bore x 83.8mm stroke result in a displacement of just 499.0 cubic centimeters.


The bike has a 4-speed, manual transmission. Power was moderated via the wet multi-disc, manual.


It came with a 3.25 x 18 front tire and a 3.5 x 18 rear tire. Stopping was achieved via drum in the front and a drum in the rear. The front suspension was a telescopic fork while the rear was equipped with a dual shocks. The wheelbase was 54.02 inches (1372 mm) long.

1971 - 1973 BSA B50 MXEdit


The 1971 BSA B50 MX sports an air-cooled, four-stroke, 499cc, single cylinder powerplant mated to a four-speed manual transmission and can produce a claimed 34 horsepower and 38 Nm of torque. This off-road machine was one of the most successful moto-cross machines designed by BSA, and had standard fittings such as a single seat, a small fuel tank, wide handlebars, a telescopic front fork coupled to dual shocks as a rear suspension, laced wheels with knobby tires mounted on them, a black steel frame and drum brakes in the front and in the rear.