BSA B40 Parts & Spares
The B40 is the 350cc version of BSA's unit single, and the one that stayed in service longest thanks to the WD machines built for military use. Civilian and military bikes differ in more than paint, and the parts that separate them are usually the ones holding up a rebuild.
Obsolete Bike Parts holds over 40 B40 line items, WD-specific fittings among them.
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€ 196,00 Select options This product has multiple variants. The options may be chosen on the product page
Civilian and WD
The B40 ran from 1960 in Star and SS form, and the WD B40 stayed in military service well into the seventies. Military machines carry their own frame fittings, electrics and ancillaries, and reproduction parts are not always to the correct pattern. Our listings say which they suit, and we can check a frame number for you.
What we stock
- Bottom end: crankshaft assemblies, conrods complete with bushes, crankcase hardware
- Top end: valves and guides, rocker boxes complete, cylinder head gaskets
- Gearbox and clutch: gear clusters, kickstart parts, clutch components
- Chassis: centre stands, swinging-arm spindles, engine protection shields
Shared with the rest of the unit range
Many B40 parts also fit the B44, and some carry across to the smaller C15. Where a component is common to more than one we list it under each; if you cannot find it, ask.







