Can someone please confirm the comp ratio on these pistons for me - '59 A10 +60
Thanks
pistons_1a.jpgpistons_2a.jpg
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.
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.
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.
Thanks guys, I'll start searching for numbers.