Different cylinders for the same bike?

I was looking for a piston to rebuild my bike and on ebay there are some listed for c cylinders, std cylinders, etc. what does this mean?

STD stands for standard, as in no overbore (sometimes you can buy overbore pistons OEM)


I couldn't tell you what C means, or what else letters there are, but if you are looking for the same cylinder you have now, go with STD.

From the factory YAMAHA makes 4 sizes... A B C and D, A being the smallest and D being the largest. In the owners manual it states the different sizes and the tolerances and limits of each. Apparently if you have an "A" cylinder you should run an "A" piston through it and after a top end or two you can enlarge to a "D" size top end. Here is a picture of the manual

ImageUploadedByThumper Talk1380498456.082584.jpg

This shows relationship of sizes

Edited by Bremer120

I ordered a new cylinder and piston kit (all OEM) and received both "B." I have heard if you order it's more luck if the draw. It wasn't specified when I ordered. Nor, could I choose, I just ended up with matching sizes. Ideally you want a smaller cylinder and grow into the "D" piston

They used to list them as colors:). Call up and order a purple piston:).

when each cylinder is made in the factory they are supposed tobe the same size, but there will always be different sizes, the cutter that makes the cylinder bore wears down over time. different hones wear etc, Once complete each cylinder is measured, depending what size it is it falls into A B C or D size, and gets stamped accordingly,

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now