| Listed in parts books | Not catalogued by year yet |
BSA PISTON B34 8.5:1 +070
A B34 piston, 8.5:1 compression ratio, +070 oversize.
This is a B34 piston listed at 8.5:1 compression, in the +070 oversize. The manufacturer tag on this one reads Amal in our system, but that's almost certainly a mismatch in our records — Amal makes carburetors, not pistons, so take that tag with a grain of salt.
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We don't have much more on file for this part number beyond the basic description. If you're rebuilding a B34 motor and need this bore size and compression ratio, give us a call and we can confirm what we've got and whether it matches what your engine needs.
Oversize pistons like this are typically fitted after a cylinder has been rebored to clean up wear, so if you're ordering a +070 you likely already know your bore has been taken out to that size.
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