Original BSA pistons went up to .040" oversize...After market pistons (like Hepolite) went up to +.060" oversize...Plus .080" pistons aren't generally available..Beyond .060" a new cylinder liner is usually fitted and the cylinder returned to a 'standard' 82mm size...Ian
Thank you all for info.Yes i will have to change liner and start again with 82. I saw some gandini pistons for m21 +0,80 and i hoped that i will find some for m20.
