Have Boat Questions? Ask a Boat Repair Expert.
So the biggest problem you have is getting it on plane? If the boat is lightly loaded how does it do? Does it idle well? Is this something that has just started?
If the timing is OK then the ignition should be fine, that compression is fine. That really leaves fuel or set up.
Post back with your answers to these questions.
With the engine down check where the cavitation plate of the lower unit is in relationship to the bottom of the boat. How much higher? It is probably too high on the transom.
Did you replace the propeller?
Do you have any rpm figures?
Being that high will make it a bit harder to get on plane.
Let me look up the timing specs on that engine. If the timing is off it will cause lack of power problems. I'll get back to you in the morning from the shop.
On the starboard side magneto plate are some marks for the timing. With the throttle at full throttle, forward gear, engine off, check that the 25* mark on the plate is lined up with the split line between the crankcase halves. Adjust the throttle stop as necessary.
If the timing is off by more than a few degrees then it will make it harder to get on plane.
If the engine wants to bog down when getting on plane try to enrichen the idle mixture screw 1/8 of a turn.
Let me know what you have.
There should be timing marks on the plate under the flywheel.
Let me get you a pdf in the morning.
here is a pdf of the timing.
I tried it on another computer and it comes through for me. Do you have a pdf viewer on your computer? If not it is a free download from Adobe Acrobat.
You ran the Yamaha prop with no problems correct?
Run the engine, have a friend at the throttle. Remove the air silencer from in front of the carb. Squirt a little fuel into the carb while trying to accelerate, does the rpm go up?
Let me know, curious problem. Check the sync between the carb and ignition. The timing should be at wide open or nearly so before the carb opens. If the carb opens too soon it will bog down.
On the same page as the timing I sent is the throttle cam sync. As you can see from the design of the cam it causes the timing to advance before the carb really opens much. Is your throttle adjusted this way?