1955 Evirude Fleetwin 7.5 hp low on power

[Greg O.]

I just replaced the water pump , set the points, cleaned the carburetor on this motor. I barrel tested it. Idles very smooth. But when I put it on the boat I did not feel like it was revving like it should. So I recorded it then compared it to this YouTube. http://m.youtube.com/watch?v=g2RiTzg0WVw

Sure enough it is only running about 2/3 the speed of the fine running motor on YouTube. When I last checked compression it was 75 on one and 80 on the other.

 

[Greg O.]

And the throttle is opening.

 

[Daviet]

Did you adjust the high speed needle valve with the throttle wide open?

 

[Greg O.]

I ment to mention I turned the high speed needle until it was obviously running rich, then slowly backed it down to best condition. I also played with the trim angle, which seemed to be best in the second setting from the bottom.

 

[ddwilson]

might check the spark an make sure it is firing on both cylinders.

 

[Chinewalker]

I'd verify that it's running on both cylinders. Can be done with cylinder drop test - removing one plug wire at a time and noting any changes.

 

[racerone]

Slip clutch in lower unit might be jamming up.--Found below the waterpump.

 

[Greg O.]

How can the slip clutch jam up?