Re: 18HP saga continues. Can’t get past 14mph and 3,900 RPM.

[Don]

quote BillW:

I know you have tried three power heads. However I still would like to know the compression. 18s are unstoppable and get used and abused until the cows come home. Thus, they are often found with high cylinder wear. They will still run like a fine Swiss watch at lower speed, even with this wear. If you haven’t got 115 psi or better, you may not ever make it to 4500. Many times, you see them with 90, even 80 psi compression and they are smooth as silk; but the power just isn’t there.

At this point, you have been whipping this thing forever; so it is more of a matter of pride than money, that you get it to work. If I were you, I would rig it up with an adjustable high speed jet carb bowl or whole carb, at least as an experiment and see if that helps.

I like this idea…..The high speed needle might be too long and interfere with the lower pan though…
I have quickly reread this thread, but I don’t see anything about the prop style/pitch, pictures of the boat, or a description of the tachometer you are using….15MPH does seem way too slow for an 18hp though, have you tried it on a different boat?