Motorcycle Classics

1957 BSA A7 Twin

Reader Contribution by The Motorcycle Classics Staff

1957 BSA A7 Twin

Country: Great Britain
Engine: Air-cooled vertical twin 4-stroke
Ignition: Lucas magneto
Power Rating: 28hp @ 5,800rpm
Bore x Stroke: 66mm x 72.6mm
Displacement: 497cc
Valves: Overhead, pushrod activated
Fuel System: Single Amal Monobloc 15/16” bore carburetor
Transmission: 4-speed
Suspension: Front telescopic forks, rear twin shocks
Brakes: Front and rear drum
Weight: 425lb (dry)
Top Speed: 90mph

While never having the popularity of the Triumph twins, the BSA twins were very well engineered and in many respects, easier to service than the Triumphs. These A7 twins were quite versatile, from winning the Daytona 200 in the early ’50s to competing in the International Six Day Trials. At this point in time, BSA was the largest producer of motorcycles in the world.

  • Published on Apr 23, 2014
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