V20 vs V21

[phatdaddy]

take a spark tester also, could be only hitting on 3 cyl.

[Destroyer]

Spark plug tester, compression tester, and def look at the pitch of the prop. Check engine compression with the engine warm, not cold. Prop should be around a 15-17p (avg) for these boats with a 150 engine. 19 would be pushing it and anything over that is probably overpitched and will have a detrimental effect on performance and engine longevity. (IMHO). Also, do a little homework and find out the engine mfg's recommended WOT rpm's for that engine. Then look at the tach while out in the water and see where you are in relation to that number at WOT. That should give you an indication of how the engine is performing relative to the pitch of the prop.

[carbinebo]

Thanks for the input.

The tach isn't working. I can tell it's nowhere near where it should be though.
It just does plane. My buddy's 18 whaler outrage has a 150 Yamaha so I'm familiar with the power of this motor.

I'll probably continue my search for a CC.

Bo

[Destroyer]

As has been observed here several times, it could be as little as a loose spark plug wire. Don't give up on it so fast. Or, it may be something very serious and it's time to walk. You just don't have enough info yet to make an informed decision.