If a piston for a kohler engine is an oversize piston, is that stamped on the face of the piston?

yes more then likley it will have the oversized stamped on teh piston in .010 .020 etc|||really the only way to know whould have it mic to know what size it it most of the time you can re ring three times before boring and many times three times boring it all most motors will take...so have it measured you will know for sure... any good auto parts and shop should have the tool