BSA Twin Parts & Spares
This page gathers the parts that belong to more than one BSA twin. Many components were carried across models for years, so a crankcase, a fork part or a lamp bracket often suits both the 500 and the 650 of the same generation. Listing them here saves you searching every model page separately.
Obsolete Bike Parts keeps shared engine and frame parts for the BSA twins, including complete A50 and A65 crankcases, fork stanchions and damper rods, brake plates and small trim items. Each listing names the models it suits, and parts for a single model stay on that model’s own page.
- € 196,00 Select options This product has multiple variants. The options may be chosen on the product page
Pre-unit or unit construction?
BSA built two families of parallel twin. The pre-unit A7 and A10 carry a separate gearbox behind the engine, and the unit-construction A50 and A65 that replaced them from 1962 share their crankcases with the gearbox. Almost nothing inside the engine crosses between the two families. Within a family the overlap is much larger: the 500 and 650 unit twins share most crankcase, frame and electrical parts, while bore-related parts follow capacity. Your engine prefix tells you which family and size you have. The pre-unit frames also moved from plunger to swinging-arm rear suspension during the A7 and A10 years, which matters for frame and rear-end parts.
Shared BSA twin parts
- Engine: complete A50 and A65 crankcases, covers and engine fittings
- Front end: fork stanchions, damper rods and fork hardware
- Brakes: brake plates, including a pattern shared with the Triumph twins
- Frame and trim: rear lamp supports, styling strips and brackets
Check the model before you order
Where a part covers only certain years, the listing says so. If yours does not match what you see, send us the engine and frame numbers. Where a part has been reproduced to a later pattern, we note that on the listing too.