I recently purchased a 13 ft Boston whaler with a 1989 Mercury 40 hp 4 cylinder 2 stroke. It starts right up and will rev in neutral, but when I go to get on a plane it bogs down and only makes it to about 15 knots (4100 rpm). I've cleaned the carbs, changed the spark plugs, checked the compression (120 on all), new fuel line, new impeller (unrelated), and I've changed the top spark plug boot and contact. Also I had a mechanic take a look at it and he replaced the number 1 cylinder coil which did absolutely nothing. If anyone has an idea of what could be the problem I'd be happy to hear anything. I'm suspecting the stator at this point because the engine does not seem to be charging the battery.
Ps. Here is a video of a guy with the same problem: https://youtu.be/eQG905bi2b8
Ps. Here is a video of a guy with the same problem: https://youtu.be/eQG905bi2b8
