1986 Yamaha 25hp doesn’t do good under a load

[Mattkline205]

I have a 1986 Yamaha 25hp European model I recently replaced the coil and wires and fuel pump and cleaned the carb 2 times and replaced all the fuel lines and filter under the cowling. The motor has 120psi compression on both cylinders and will sit there and idle all day but as soon as I take off and full throttle it just doesn’t get to the rpms that it seems like it should I got it to one time while I pumped the primer bulb and throttled it so I suspected fuel pump I replaced it and still doesn’t rev like it should under a load.

[99yam40]

is the timing advancing like it should, timing light comes in handy to see what it is doing

[Mattkline205]

I have no idea how to check the timing on it to tell you the truth

[99yam40]

have you ever used a timing light on any type of motor?

[Mattkline205]

I could do it I just need to know how much advance the timing needs to be wot

[99yam40]

service manual for your motor will have all specs
Not sure if many around here have a manual for your old motor to give you that info
take a reading with a timing light and post up what you find.
maybe someone can let you know if it sounds close.

plus knowing the timing is advancing is the main thing.

more fuel and timing advancing is needed to get more power

does pumping the bulb help every time?

[Mattkline205]

Pumping the bulb only helped one or two times then it just ended up flooding the motor. I know some carbs you have to tune the float and I tried that with this one where you hold the carb upside down and level and make sure the float is level but when I did that it didn’t allow enough gas in there

[99yam40]

motor cannot or rather should not flood by pumping the primer bulb, the floats should seal off the fuel once bowls are full.
service manual will have specs for setting that also