| Also known as | E8124 |
| Diagram | Fig. 2 — CRANKCASE · ref 45 |
| Subsystem | engine bottom |
| Listed in parts books | 1968, 1970–1971 |
SPRING CHECK VALVE B25
Check valve spring, PN 70-8124, listed for the Triumph 250 TR25W (1968–1971) and the BSA B25.
This is a check valve spring, part number 70-8124, listed in the crankcase and gear cluster/timing cover sections of the parts books. Our own Triumph parts books tie this number to the Triumph 250 TR25W, with catalog years running 1968 to 1971, and the catalog description itself calls out the BSA B25 as well, though no BSA years are given in our records. So this one covers both marques rather than just the one the number format might suggest.
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A check valve spring is a small return-oil or non-return type spring working with a ball to control oil flow direction inside the crankcase area — that's the general job of this class of part. Beyond that, our records don't give further detail on placement or spec for this specific piece.
It's also cataloged under 94125K523 and E8124, so if you're working from an older book or a different numbering system, those are the same part. Give the shop a call if you want us to confirm which application you're working from before you order.
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