I have twin 496 Mag Ho's in a 35 Fountain Executioner. At full throttle all I can get is 4K. This is true for both motors. There is no difference in RPM's with the last 1 inch of travel on the throttles. The boat is a dog coming out of the hole. The rear of the boat at the exhaust is covered with a black film. Any suggestions?

Did You Just Buy This? Sounds Like Props Are To Big.

Are you trying to running with your drives all the way in? What props?

sounds like the motors are in Guardian mode. Get em scanned and youll likely find the issue.

sounds like too big of props to me, the 496's can be pretty sooty motors especially if you dont run regular gas..

My 496s would run sooty til I got about 20 hrs on them that is supposed to be a break in period but I never had issues with low rpm, check props, one of my motors went into guardian mode from getting hot & all it would do is idle til it cooled down

I think we need more info.

Check the injectors, I had very similar problems.

Some soot is normal. I agree that it is over propped. If you just bought it then it is possible that the owner switched props before selling it.

what altitude?