| Diagram | Fig. 3 — CRANKSHAFT · ref 25 |
| Subsystem | engine bottom |
| Listed in parts books | 1969–1972 |
BSA Shell — connecting rod big-end (·020" undersize)
A .020 inch undersize connecting rod big-end bearing shell for a reground crankshaft journal.
This is a big-end bearing shell for the connecting rod, machined .020 inch undersize to suit a reground crankshaft journal. It sits in the crankcase where the connecting rod meets the crankshaft, part of the assembly that lets the rod rotate around the crank pin without excessive play.
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The catalog places this shell in the crankshaft and piston figures, and it shows up across several years in our records, but the exact model and engine size aren't spelled out beyond that. If your crank has already been reground once, this undersize shell is the one to check against your measured journal diameter before ordering.
Give us a call if you're not sure whether your crankshaft has been reground to this undersize or still on standard — matching the shell to the actual journal size is the part that matters here.
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