Piston ID?

[Grahm]

Im trying to figure out what size my piston is for my tri-z 250

It say cm on top and 504 on the inside bottom.And has a little W with a circle around it on the inside too.

I googled that but couldn't come up with anything

[just ben]

the w in the circle says it's a wiseco that mark should be on the bottom where the wrist pin goes through. on the top it should have 515 p# ( p1 for .25mm over p2 for.5mm ect.) if it's the newer part number it will haave mo5150 then the bore size

[Grahm]

I measured it and it was standard piston/bore...Just said cm on top and that's it unless it wore off.