| Diagram | Fig. 5 — OIL PUMP, GEARBOX SPROCKET · ref 4 |
| Subsystem | gearbox |
| Listed in parts books | 1969–1972 |
GEARBOX SPROCKET 20T BSA A65 - UK
20 tooth gearbox sprocket for BSA A50 and A65 twins, one tooth up from the standard 19T sprocket.
This is a gearbox sprocket for BSA A50 and A65 twins, cut with 20 teeth. It's the part that sits on the end of the gearbox mainshaft and carries the final drive chain back to the rear wheel sprocket. The 20 tooth count is one up from the standard 19 tooth sprocket, which has the effect of raising the gearing slightly for a bit less engine RPM at a given road speed.
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The catalog carries this under PN 68-3073, also listed as SPR-A6520T. It's a BSA part, not a Triumph one, even though it lives in a Triumph-heavy parts numbering system here at the shop.
We don't have much more on file for this one beyond the basic listing, so if you're not sure whether your gearbox and chain setup can take the 20 tooth in place of the stock 19, give us a call and we'll talk through it before you order.
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