i have a 1982 atc 250r and i am wanting to replace the piston and rings and was wondering how can i tell if the piston is stock or not?
is there somewhere on the piston that tells you if its stock or if its been bored out or anything?
someone please help

 

If its a Weisco brand replacement piston, it will have a part # you can look up on their website...

Probably best to actually measure the cylinder bore & make sure it's within the range for whatever size the piston is.

Getting it bored should only cost about $50- 60, if you're replacing the piston anyway. (Rebuild will last longer if you have a smooth, consistant cylinder)

 

At one time they were stamped into the head and when you cleaned the piston you could see if it was oversized .. Now most are etched either on the top or beside the wristpin hole.. A stock has no stamp but the piston should be measured anyway ..

Here are a few examples of 1st over pistons , 2 are etched 1 is stamped

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thank you guys for the help i did find out that it was a stock piston that had been replaced not too long ago and had a new sleeve put and got that all squared away.
but once again thanks for the help.