yamaha 75 year 2001 powertrim tilt problem

[johnstevenclifford]

I have the yam 75 2 stroke 2001 will work fine on the trim ,ie the 2 cylinders but then will not go onto the tilt system .the motor slows right down. I can stand on the cavitation plate and the trim system will lift me up and down so I guess the motor is ok. There are no leaks and the oil level is right.I have bled the system ,im thinking the main valve assy is at fault any outboard mech,s outhere.