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I am rebuilding the top end of my o1 gp1200r. I just want to make sure i am looking at the correct number on the cylinder to get the correct piston. I am looking at the number on the top of the cylinder on the top left corner, viewing the cylinder from the carb side. Is this correct?

My cylinders are marked 18, 18, 8? Is it common to have mixed style cylinders?

What happens if you are not using the correct piston, the difference seems so small that there would be no harm.

Any useful input is always welcomed.

Thanks, wagz

Usually the numbers are closer together than that, if not all the same. Sounds like that cylinder (#8) is a replacement. It's not a problem though.

You need a certain amount of clearance between the piston and cylinder wall. If the clearance is too small you run the chance of seizing when the piston expands during operation.

Thank you. I just found out that Pro-X does NOT make a piston for the #18 cylinders. Do you know of anyone that would do an exchange of the cylinders. I need a cylinder marked 1-15. My cylinders are clean, absolutely no damage at all.

Wagz