I just bought a boat that has a 115 Mercury outboard 2 stroke and the guy i bought it from told me it had a hole in one of the pistons, I tore it down and removed the piston, inspecting the other three cylinders and pistons they are in good condition, no scaring on the pison or cylinder walls. The question i have is what is the possible causes for just one piston getting in this shape and not any of the other ones. I've attached a ppicture of the damaged piston, any thoughts on this is great, I'm ordering another pison and rings to replace this one and what to correct any problem that might exist to prevent this from happening again. Alittle info about the motor: The motor is oil injected, The compression on the other three cyilinders is 125-130.