1983 ATC250R piston help

[Mrven157]

So i need a new piston for my 1983 atc250r. It has a big bore kit on it but not sure how big. I measured the old piston with my calipers (which are in standard) and converted to metric it reads about 75.4062mm. Im need help finding a replacement piston. What is the cc? Wiseco sizes there piston by .020, .040, .060 over so what do i need?

[yaegerb]

Sooooo, that's an odd measurement. 300 kits std piston is 76mm. The largest over bore for a stock cylinder is 72mm. I would check the measurement again.

[Mrven157]

Sorry it's an aftermarket cylinder head also

[yaegerb]

Sorry it's an aftermarket cylinder head also

Post some pics of the engine/cylinder/head so we can see what we are dealing with.

[Mrven157]

Ok I will when I get home today. I couldn't really see any identification of any sort on it.