mefi 4
 

Motor will not rev over 5200 rpm in boat.Any help???When on the dyno pulled 6200 with no problem.And the prop is not to big.

See this problem a lot. In basic terms a dyno lets the motor rev up to get to max HP & RPM. Boat is the same as a dyno except it will not let the motor gain RPM to the next level.

We need more info. Such as what is different between dyno run & in the boat. Fuel system, iginition, exhaust, or air intake. What is the motor? Most inportant what are the specs on the engine, Cam, heads & ??? Is this a dual engine setup, Single Setup? If dual both motors have same problem? What outdrive(s)? What gear ratio in outdrive? What prop(s) are you running? Why are you saying "prop is not to big"? What speed are you seeing? If you have the dyno run can you post it?