1973 BSA B50MX


1973 BSA B50MX

1973 BSA B50MX BACKGROUND
BSA produced one of the world’s most successful 500cc singles in the Gold Star starting in 1938 and running all the way through 1963 when production ended. The entire BSA product line was being converted from non-unit construction to unit-construction and the ancient non-unit Gold Star had to go. It was replaced not by an updated version of itself, but instead by an entirely new bike with unit construction. It took a few years to bring it up to size, because the new unit-construction BSA single started out life as the 250cc C15 Starfire in 1963, then the B44 441cc Victor in 1967. It took until 1971 to punch the big single out to its final displacement of 499cc with the B50 lineup. This included the B50SS (a Street Scrambler), the B50T (Victor Trail), and the B50MX (Moto Cross) pictured here. The BSA B50s were built in 1971 and 1972, but unsold units were retitled and sold as 1973s. BSA built its last motorcycle in 1972.


1973 BSA B50MX Specifications

Engine type
Displacement
Bore & Stroke
Compression ratio
Carburetor
Ignition
Horsepower output
Torque output
Primary drive
Clutch
Gearbox
Final drive
Battery
Frame type
Suspension, front
Suspension, rear
Brake, front
Brake, rear
Tire, front
Tire, rear
Wheelbase
Length
Width
Height
Ground Clearance
Seat Height
Dry Weight
Air-cooled OHV 4-stroke single
499cc / 30.5 ci
84mm X 90mm
10.0:1
Amal 932/28
Lucas RM21 points & coil
34 hp @ 6200 rpm
28 lb/ft @ 5000 rpm
Chain
Multi-plate, wet
4-speed, right-foot shift
Chain
12 volt
Welded steel tubing, oil-in-backbone
Telescopic forks, hydraulic damping
Swing arm w/2 shock coil-over shocks
8-inch TLS drum, conical hub
7-inch SLS drum, conical hub
3.25″ X 18″
3.50″ X 18″
54.0 in / 1372mm
85.0 in / 2159mm
29.0 in / 737mm
43.5 in / 1105mm
7.0 in / 178mm
32.0 in / 813mm
310 lbs / 140.6 kg

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