Things to check on cylinder bore?

[crofty1984]

Hi all,
My Starfire (250 BSA single) was losing compression and wouldn't run. Oil down the bore improved the compression, pointing to rings. While I've got the head and barrel off, how do I check to make sure the cylinder bore is OK and is there anything else I should consider doing?
The bore feels very smooth to the touch and there's no obvious signs of damage to it or the rings.

[Rubin215]

Take it to an engineer and get it properly measured.
Bores gradually become oval in use due to the thrust of the piston; you can't see this with the eye.

Cheapest is honing the bore and fitting new rings, but you are probably best just getting it bored out a little any fitting a new piston and rings anyway.

[Tango13]

Depending on which bit of Norfolk you are drop me a PM and I can measure the barrel for you, I'm just outside Skeg-vegas.

[srob]

crofty1984 said:

Hi all,
My Starfire (250 BSA single) was losing compression and wouldn't run. Oil down the bore improved the compression, pointing to rings. While I've got the head and barrel off, how do I check to make sure the cylinder bore is OK and is there anything else I should consider doing?
The bore feels very smooth to the touch and there's no obvious signs of damage to it or the rings.

We’ve just found a really good place just outside Diss. The old man’s just had his Velo MSS rebored by them. They measured it and it wasn’t much money at all and they seem to have done a really good job