I have a two cylinder with one burnt piston and cylinder wall. I am being told to replace one piston with an oversize after Boring the one cylinder wall to .020 over (Hopefully that is all that will be required). I am being told since the other cylinder wall and piston look fine to leave it alone and only replace the rings and maybe hone lightly the other cylinder wall. Does this sound right? Certainly not what I am accutomed to with cars motors. I still do not know why this one burnt. Carbon on piston indicating good fuel and oil. Burnt on exhaust side the top and side of piston. This was the lower piston on my two cylinder.