| Also known as | GAN46 |
| Listed in parts books | Not catalogued by year yet |
PISTON,BSA B44 +.040 GPM
Piston for the BSA B44 single, machined +.040 over standard bore.
This is a piston for the BSA B44 single, machined to +.040 oversize for a rebore. It's listed as a GPM piston, which is a brand designation you'll see stamped or noted on piston boxes from that era of British bike parts supply. The +.040 size means it's meant for a cylinder that's already been bored out that amount over standard, so you'd only order this if your barrel has been machined to match.
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This isn't a Triumph part — the description is plain about it being for the BSA B44, so if you're working on a B44 motor and your bore has been taken out to the +.040 mark, this is the piston that corresponds to that spec. We don't have much more detail in our records beyond the description and the oversize callout.
We also show this part under the number GAN46, so if that's what's printed in your book or on an old invoice, it's the same physical piston. Give us a call if you want to confirm bore spec or ring set compatibility before ordering, since piston fitment is not something you want to guess on.
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