BSA Stroker

BSA A65 stroker crankshafts can be made in two ways; by modifying an A10 crankshaft (84mm stroke) or by modifying a Norton crankshaft (89mm). The timing side journal can be ground to 1.500” stock size or ground for a roller bearing with an oil feed quill The crankshaft diameter, with counterweights, is about 3/8” smaller then a stock crankshaft to clear any high-lift camshafts and reduce the rotational weight of the crankshaft. Our crankshafts are usually 4.5 pounds lighter than a stock crankshaft.

Donor large-journal BSA A10 crankshafts are very hard to find. Modification of the A10 crank width and journal location for an A65 engine means there is no discount for supplying an A10 crankshaft.

An A10 crankshaft modified for an A65 engine crankshaft costs $1400 USD. A Norton crankshaft modified for an A65 or A10 engine crankshaft costs $1500 USD. This crankshaft is supplied with a lightweight flywheel unless the customer specifies that the full-circle version is required as noted under Norton crankshaft links on this site.

Note that drive shaft end of a BSA stroker crank uses a stud, a top-hat nut and an anchor washer to mount the alternator similar to a Triumph crankshaft; these parts are supplied with the stroker crankshaft.

All 76 degree versions of BSA stroker cranks cost $200 USD more than quoted prices shown below except where noted. Contact SRM Classic Bikes for information about the barrels and connecting rods they supply for BSA stroker engines.

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