Yamaha 89, 90hp, Lose power

[malain123]

It's a 2 strokes, when the motor is wamed up and I go high speed, it loses power.
I rebuiled the gas pump I checked the pressure it is 2 1/2 psi (wich is ok according to fabricant), changed the spark plugs, changed the gas line from gas tank to motor. Still have the same problem. Help would be greatly appreciated.

Thank you.

 

[rodbolt]

Re: Yamaha 89, 90hp, Lose power

you can try squirting premix in the carbs at the trouble RPM and see if it changes.
a clogged main jet can cause the symptoms. also check the cdi output voltage at the problem RPM, this will require a peak reading meter or a DVM with a DVA adapter but will quickly confirm the CDI.
those carbs are quite simple and easily cleaned.