ID Comp ratio please

[limeyrob]

Can someone please confirm the comp ratio on these pistons for me - '59 A10 +60

Thanks

[limeyrob]

OK let me rephrase this:

How confident are you these are 9:1?

I want to get some rings ordered and they are for 9:1 pistons but all the images say "not actual item" which is not very helpful.
Engine is rebuilt (bottom end and head) and running well (but a bit rich) and was blowing a bit of oil out the breathe, Rings came with the bike so are an unknown quantity.
I'll post a new thread about the breathing as there are several questions.

[DAVE BRADY]

Hi Bob,

I think the make of piston is more important than the CR. Do you know what make they are. The chances are that they are usual spec. rings.

Dave.

[JulianS]

They look like 9:1, if they are genuine old English made Hepolites there will be a cast in number on the inside near to the bottom of the skirt, the 9:1 part number is 11412. Genuine BSA made pistons often had the part number stamped on the crown.

[limeyrob]

Thanks guys, I'll start searching for numbers.