Hey guys I got a 75 DT250 that unfortunately needs to be bore out, the issue im having is finding a 10 over piston. From what i seen on wiseco's site they dont have a 10 over they go straight to 20 over. I been searching around using part number 438-11635-01-00 but have had no luck except for a recent listing on ebay for a used one.
I could go straight to the 20 and save myself the head ache but i hate cutting the life of it down anymore then i have to. If anyone knows where i can find a 10 over id greatly appreciate it.

Contact the "original" Enduronut here... one word... or maybe DEET. Email addresses can be found by searching forum.

Oh, forgot to say Yamaha used metric so what you're looking for is a 0.25mm over... which is very close to 0.010" over. But you probably knew that already.

Enduronut has quite a stash of pistons and rings.

Thanks Mark as usual your knowledge is always most helpful! i shall reach out to them now. You are correct about me knowing about the 0.25mm but it always helps to throw the info out for other people its amazing how much info is on this site!

This might be an option providing the pin size & distance to the top is the same but yamaha are pretty good at keeping things interchangeable through the years. Nice looking piston. Clearance they quote might be a fraction of a fraction more than desired but you take the piston with you & the shop bores it to clearance you state. Second link is to another forum that i saw DT250 mentioned to do with piston interchangeability.
www.vintco.com/Yamaha-YZ250-1980-81-IT25...-70.25mm-0.25mm-Over

www.trialscentral.com/forums/topic/67312...ources-and-opinions/