Piston Compatability

I'm curious as to what the differences between the 2000 thru 2002 yz426f pistons are and the piston in a 2003 vs 2004 yz450f. What pistons will work in what motor or years? I'm talking about OEM pistons

There is no difference in pistons between a 2000 vs 2002 YZ426F and the same goes for a 2003 vs 2004 YZ450F. There is a bit of a difference between 2002 YZ426F and 2003 YZ450F pistons. What I have found is a 426 runs a 19mm wrist pin and has a 24.1mm compression height. The 450 runs a 18mm pin and a 23.5mm compression height.

Edited by jojo1224

I have two pistons, a 5NG y3 and a 5NG y2, is there any difference between these two pistons? If so what

A 5NG piston would fit either a YZ/WR426. The y2 and y3 is most likely the identifier for what revision the part is. The way Yamaha part numbers work is the first three digits are the model identifier, the next five are part code, next two digits are revisions followed by two zeros. In this case 5NG-11631-10-00 so 5NG means it is for a 426, 11631 means its a std size 5 valve piston and 10 means its been revised/updated once. I am not sure what changed between your two pistons but if you are going to use one use 5NG y3. Is there anything different you see looking at the two pistons?

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