Hello I need help with this issue, it's been this way since the rebuilt.

Up to 3/4 throttle the motor accelerates as normal, beyond 3/4 it stops accelerating and remain at the same speed.
It has a Simon programmed ECU, new coils/electronics and alternator. Because of corrosion issues, the two piece exhaust plate was change to a Optimax 150 with the exhaust adapter being machine to match the 200 exhaust tube.

The 26" prop is even with the bottom of the xb2003. Currently the Top speed is 70, ~5700rpm.


Any thoughts on what is causing the loss of power, can the 150 exhaust plate be the issue.

thanks