c.1949 BSA 350cc B31 Project

Motorcycles Online - The Summer Sale|15 June 2026, 15:09 BST|Online, Milton Keynes

c.1949 BSA 350cc B31 Project

Registration no. not registered
Frame no. ZB31S.220
Engine no. ZB31.26358. (see text)

BSA's rugged, workaday B31 was manufactured from 1945 to the end of 1959, its overhead-valve engine providing the basis for the renowned Gold Star sports roadster. At the time of its introduction, the B31 was BSA's sole all-new model, joining the lightweight 'C' and heavyweight 'M' ranges carried over from pre-war days. Produced initially with rigid frame and telescopic front fork, the B31 gained (optional) plunger rear suspension in 1949 and an all-new swinging-arm frame in '54. A good all-round performer by the standards of its time, the B31 could cruise comfortably all day at 60mph while returning 75-plus miles per gallon, virtues that endeared it to private owners and police forces alike. This much loved and highly successful model was last produced in 1959, its place in the BSA range being taken by the unitary construction B40.

This 'plunger' B31 consists of a 1949 frame and a 1952 engine. There are no documents with this Lot, which is offered for recommissioning/restoration and sold strictly as seen (the engine turns over). No history is known. Key not required.

Footnotes

BUYER'S PREMIUM
The Buyer's Premium for this Lot is 28%+VAT on the first £40k of the Hammer Price, then 27%+VAT up to £800k, then 21%+VAT up to £4.5M and 14.5%+VAT thereafter.

All lots are sold 'as is/where is' and Bidders must satisfy themselves as to the provenance, condition, age, completeness and originality prior to bidding.

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Additional information

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