BSA Motorcycle Parts & Spares
Small Heath built in volume and in variety: side-valve M-series workhorses, the B-range pushrod singles, pre-unit A7 and A10 twins, the unit A50 and A65, the C-range lightweights, the Bantam two-stroke and the A75 triple. Parts commonality within a range is good and between ranges is poor.
On this page are the BSA items we list against the marque rather than one model, together with the shared hardware that turns up in almost every rebuild: Amal carburation, Lucas electrics, fasteners and sealing. The engine and gearbox specifics live on the model pages, where the range and the year can be pinned down properly.
Finding your range
The M20 and M21 are side-valve singles with their own gearbox and cycle parts. The B31 and B33 are pushrod singles of 350 and 500, with the M33 using the 500 engine in heavier running gear. The C10, C11, C15 and the later B25 cover the lightweights, and the Bantam stands alone as a two-stroke. The twins divide at 1962, when the pre-unit A7 and A10 gave way to the unit A50 and A65.
Commonly ordered groups
- Engine hardware: gasket sets, seals, pushrod and rocker parts, fasteners
- Clutch and primary: plates, springs, chain and adjusters
- Carburation: Amal bodies, slides and jets
- Electrics: Lucas ignition, charging and lighting parts, switchgear
- Cycle parts: brake components, control cables, fork and suspension items
Not sure which range?
Send the engine number exactly as it is stamped, letters included, and the frame number with it. On BSAs those letters usually settle the model before anything else does, and where they do not, a photograph of the timing cover and the gearbox end will normally finish the job. If the machine has been apart before, say what you suspect has been swapped in: it is a far better starting point than a model name alone.