| Also known as | 90-241 |
| Diagram | Fig. 7 — GEARCHANGE MECHANISM · ref 5 |
| Subsystem | engine bottom |
| Listed in parts books | 1969 |
BSA Ball, oil pressure release valve (5/16" diameter)
A 5/16 inch steel ball for the oil pressure release valve, seating in the crankcase to regulate oil pressure.
This is the ball for the oil pressure release valve, 5/16 inch in diameter. It's a small steel ball that seats in the release valve bore in the crankcase, and it's the part that actually holds back oil pressure until it builds high enough to lift the ball off its seat and bleed pressure back to the sump.
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It shows up in the catalog under crankcase and oil pump listings, and also turns up referenced in the gearchange mechanism figure since a ball-and-spring arrangement of similar type is used there too - so don't assume every listing of this part number is the same application without checking your parts book diagram first.
The catalog record we have ties this to 1969 appearances. It's a simple wear item - if the ball or its seat gets pitted, oil pressure regulation can go sloppy, so it's worth checking if you're chasing pressure gauge readings that don't look right.
We've never carried this one. Tell us what you're after and we'll go looking — you'll get a price and photos before you commit to anything.
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