Hi, recently purchased a very low hour 95 Yamaha pro 50 at a great price. Initially would not start so I removed the 3 carbs as engine had sat for a year or 2 and gave them a good cleaning. Once cleaned reinstalled them and engine started well but once it warmed up would not idle, but ran fairly well at a higher speed. Brought home from lake and compression test shows #1-135, #2-120 and #3-140, pulled power head and now looking at 2 pistons top and middle with chunks taken out of them but rings still intact! Anyone ever seen anything like this? I believe previous owner mentioned he had a new water pump installed so I wonder if this is the result of an over heated engine. Also would like to confirm cylinder numbering on this engine is top#1, mid#2 and bottom#3? Going in to crank case to pull pistons out, Not a mechanic just a diY'er so any help/comments will be appreciated. Thanks in advance.