I agree with BarracudaHockey. AB? have such a tight tolerance at/near TDC that any lack of lubed due to a lean mixture can make the piston stick to the liner, scraping off some of the chrome/nickel plating.
I wonder why someone doesn't make a chrome/nickel lined ringed motor? It would cost extra, but talk about a low friction. While still it's possible for the chrome to be damaged, it is much 'slicker' than a plain steel liner. I know it makes a difference on V6 outboard boat motors.