| Diagram | Fig. 30 — A70 MODEL — Except for the following, all other items are as A65 Lightning · ref 18 |
| Listed in parts books | 1972 |
BSA Piston complete (·040" oversize)
A .040 oversize complete piston for the BSA A70.
This is a complete piston for the BSA A70, sized at .040 inch oversize for a rebore. The catalog entry for 71-2885 sits under the A70 model listing, with a note that the A70 shares most components with the A65 Lightning except for a handful of specific items called out separately - this piston being one of them.
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Being a .040 oversize piston, it's meant for a cylinder that's already been bored out that far to clean up wear or damage, not a standard-bore replacement. "Complete" in the description usually means it comes with rings and pin, but confirm what's actually in the box before you order.
This is a BSA part, not a Triumph part, despite what shop it's sitting on the shelf in. If you're working on an A70, double check your bore size against what's actually in the barrel before ordering - oversize pistons are specific to how much metal has already been removed.
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