Riddle me this... Need a quick answer for a YZ125

I just bought a replacement cylinder and head for my 2001 YZ125 but the Cylinder and head are from a 2003 YZ 125. When I go to order the piston and gaskets everything is for 98-2001. So do I buy a Piston kit for a 2001 or 2003 and the same goes for the top end gasket set. I appreciate the help.

I would say a 2003 because the piston wil be going in the 03 cylinder. Are you 100% sure you can use the 03 cylinder and head on your bike? Im not 100% sure so wait til you get a sure answer.

I have asked a bunch and it seems to be 99-04 cylinders will work but some claim up to 03 only. They do say if using a 99-2000 cylinder on a 01 plus bike you need the head from a 99-00 and also the exhaust pipe but I never varified that. I do notice that Athena sells a cylinder kit and they list for 99-04 as well. I am just not sure if its the connecting rod that is different or the cylinder from the 01 to 03?

When you have both pistons in your hand, measure them to see what the difference is. I have a feeling that the dome of the pistons are what is different, and the shape of the head is different to match. I'm guessing you will need the head for whatever year piston you are using.

I think I figured out my answer. If I try to order a piston the range stops at 01 but if I wanted to order a hot rods crank and rod kit the range is 01-04. That's telling me that a 03 piston will work with my connecting rod so therefore I should buy a 03 Piston and gasket set.

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