Hey everyone, I just found this forum and I have a question.<br /> My nephew has a '86 Merc on a 17ft runabout that we use for fishing. The problem is when we run it at wot it will run good(24mph) for about 5min then it bogges down and will only go about 11mph (we don't have a tach hooked up)<br /> The wierd thing is it only does this with the aluminum prop on. It came with a plastic prop and when we put that on it runs almost too good(it will cavatate if the back end comes up).<br /> We troll with it all day and there no problems, either trolling or afterward on the way back in.<br /> Both props are the same pitch and are the recomended size for this motor.<br /> He took it to a mechanic and he replaced the water pump impeller and said that would fix the problem. Nope! I've checked the compression and all the cylinders are right where they should be according to specs. It starts fine even when cold.<br /> I'm at a loss, I'm good with car engines, but new to 2 cycle motors. could it be the reed valves?<br /> Any help would be great, Thanks in advance!
<br />I can't even get my own boat to run right.