I just picked up a winter project yesterday and tonight I dove into it. Like the title says I have a melted top of one of the pistons but the other 3 look great. I knew the engine had problems but I bought the boat on a gamble. I was just wondering if anyone could tell me why only one piston went bad and not the one underneith it also ? I apologize as I don't know wich # cylinder it is. I have read the good and bad about the VRO systems but there is no way that it was to blame in this incident. Is it possible there is a dirty carb and it caused a lean condition in one cylinder only ? I will become more educated on this project as I go but I'm trying to pick some brains out there so I know what common things to look for on this motor. Thanks for reading !