Thank you guys!

LarryBible: thanks! That was the type of explaination that I was searching for. I also maid that hypothesis, but I first didnt beleived in it 'cause I didnt tought that a thermal dilatation was such big as 0.5mm... But youre explaination (the piston material) seems good, and I am sure you are right.

M.BDoc: So you think that my problem (unburn fuel) can be du to bad rings? I have to mention that my oil was going black in less than 1000km's... And it was also smelling fuel...
I re-measured all the cylinders and they are really at 95.52mm. The spec are 95.50mm(New) I beileve... Is it bad or good??

Thanks again guys, I really apreciate youre advice!!