8hp surges under light load only

summitlt

Seaman Apprentice
Joined
Oct 12, 2008
Messages
40
1985 8hp johnson.

Runs fine overloaded, revs to one speed wide open. With just me on a 12' aluminum the rpm gpes up and down and boat won't plane. Carb has been rebuilt. 110psi of compression. Running on both cylinders.

Pretty much lost with this outboard. Seen smaller outboards do way better than this on bigger boats.

Things I've done:
110 psi of comepression on both cylinders
Carb rebuilt with johnson kit
Timing is advancing all the way (not predetonating)
Prop is nearly new
Spark will jump 1/2" plus on both cylinders
Fuel pump is strong
Fuel is new
Reeds are all free and opening

Where do I go next. This thing should plan a 14 empty no problem
 

Gonash

Cadet
Joined
May 18, 2012
Messages
10
Re: 8hp surges under light load only

Is the boat flopping or just about planed out then drop down again before the motor surges?
 
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