Big-Hearted Beezer: BSA/Ariel “Flash Four”

Nestling an Ariel Square Four engine into a BSA A10 Golden Flash frame creates the “Flash Four.”

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by Robert Smith

 1957/1949 BSA/Ariel “Flash Four”

Engine: 997cc OHV air-cooled Square Four MkI, 65mm x 78mm bore and stroke, 6:1 compression ratio, 35hp @ 5,500rpm
Top speed: 90mph
Carburetion: Single Solex 26 AHD
Transmission: Chain primary, BSA multiplate clutch, BSA 4-speed gearbox

  • Updated on Apr 28, 2022
  • Originally Published on Dec 10, 2019
Tagged with: ariel square four, bsa a10, lyle whitter
Motorcycle Classics Magazine
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