hope what i post now was not already treated. I searched in the forum but i did not find result

I have to grind the cylinder since the rust damaged the surface

I see that on ebay different piston size are available from the original size 95 up to 102. I understood that only the 97,93 can be used without huge modification of the engine.

Anybody did this modification? any recommendation?

Lots of considerations here perhaps try the SRX forum if you are trying to yield big power increases. What is the bore now? 95 is std the you go up in 0.25mm sizes - largest i have done is +1mm . After that i would suggest liner wall is getting too thin so you would need new liner and other works?

How about just honing it first and measuring the bore, put in new rings, or is it really deep pitting? Worth trying. Honing tools are cheap.

the actual bore is the standard 95

I agree with your consideration and the suggested step by step approach

honing first, look how deep is the pitting and decide the right size. I did not measure the liner but yes, i m with you: going higher than 96/97 would make the liner too thin

if i will have to replace the piston, do you have any brand to suggest? on ebay i see WOSSNER, PROX, WISECO

thx for support