Hey guys, long time no post!  I'm thinking i want to see if I can get my 75 DT400 running and want to order a new piston and have the cylinder bored but not sure if I should get an 85.5 or not.  Thanks for the advice/help!

Just gotta be sure it'll clean up at 85.5 as it's well on the way there by the sounds of it. Did  machine shop measure it & come up with .32 as sounds quite worn from .25. My maths aren't the best though. I'm thinking maybe go .75 to be sure. Most wear will likely be just above the ports to measure. But then again I guess a lot so see what the knowledgeable say.

Good morning Morley (it's morning here anyway), that's what I thought too about the size of .32 but I did measure with my cheap harborfrieght calipers so there's that. Hope all is well down under!