Checking piston specs for wear

[bleeds]

Hey guys,
When I am checking a piston after an examination break-down, what am I looking for to make sure the piston is within spec, and reusable?
Bleeds

 

[Uchytil]

BLEEDS, Mu opinion is replace it. The service manual will show you where to measure it (which you should have to work on that beast). Nice pic BTW, chain's on the wrong side, LOL (just like my old 125). If you are super tight on cash, and you know for a fact the piston has only a couple hours, and it is w/i spec., you could use it - but why bother. Good luck.

 

[bleeds]

The main reason why I would reuse it if I can, is this is that time of year where I dont get to spend very much (eat, wash, gas for car) on myself, and I am wanting to do some snow riding. LOL I have four kids, and I need to do this as economically as possible. The piston is a Wiseco, and the rest of the piston looks fine. I know for a fact there are only about 15 hours or less on the piston, and I dont ride hard. Mostly trail riding, and the sort. I am having the cylinder re-honed, and I am going to mic the piston. There arent any cracks. I will have to check the manual to see what the acceptable run-out is on the piston. It isnt a std piston either it is 1 size over (50MM). We shall see. If my stuff that I am selling on the Ocean Auction site sells, I will have what I need..
Bleeds

 

[nickyd]

you measure it at the top, middle and bottom - you are looking to make sure first that the piston has some taper left (ie, it should be wider at the bottom where there is less material than at the top (the top is thicker and expands more)) - second you need to measure the bore with a bore gauge if you have it. then compare the two - I'm not sure exactly what the tolerance is on that bike but ask the shop whats acceptable on any 250 - then you can make an educated decision whether or not its good - otherwise, you're throwing a dart at a moving board

 

[bleeds]

I just talked to Wiseco. They told me to measure the piston and see how far from the original size is has deviated. He said the intake scuffs arent really a big deal as long as they arent real bad. He said you can dress it a little. He said as long as there isnt more than .001 or .002 deviation I should be ok, since the piston only have about 20 hours at the absolute most. Easy hours too. No mx. BUT the rings need to be replaced without a question. We shall see. Picking up a feeler gauge tonight..
Bleeds