1995 25 mercury loosing power when engine gets hot

[kbb1991]

The serial number to this engine is g192260. It starts and runs like a top cold weather hot weather, it don't matter what i ask it to do it always starts and runs, idles with no problem. When i use it for the first 30 minutes or so it has full power but it seems as the engine heats up it starts falling on its face. It probably wouldn't be noticeable to somebody who isn't familiar with it. Its more noticeable with a bigger load, im probably loosing 5-7 mph off of my top end speed. Its not loosing power like its a fuel issue or i don't think it would run like it does the rest of the time, use seems to be what causes the problem, after it sits and cools off it seems to gain its power back and will repeat what i just explained. A buddy of mine ran a compression test on it and checked 60 pounds even in both cylinders, his theory is the rings are relaxing with the heat and its causing it to loose power. What little research i have done i found that on these older motors they have lower compression for easier manual starting and that they cant be checked like some of the more modern motors. Is their anything to what im reading or is my motor shot? I think its done for but im not much of a mechanic my self either.

 

[fastjeff]

That's NO compression! It needs a ring job.

Jeff