KX250 ring size - numbers on piston

[pkbarbiedoll]

I took the cylinder off of my KX today to replace the rings. The man I bought it from didn't remember what size he installed but mentioned there would be several numbers on the top of the piston that tells what size it is.

The numbers were barely visable, and there were two, plus the letters "CD" below the two numbers. The top # reads O0016, and the one below it reads 617M0C640.

So, what size rings do I need to order?

 

[John Cena]

Wiseco's Standard 92-2001 piston code# is: 617M06640 i'm guessing that C your seeing is really a worn out 6.
If it is stock wiseco Ring part # is: 2614CD

 

[pkbarbiedoll]

Thank you.

 

[2strokerfun]

Measure the piston. Measure the bore. A cheap electronic caliper will get you close enough.