1986 Johnson 8hp - Won't Rev

[Kiwi]

Hi

I recently bought a 1986 Johnson 8hp View attachment 1986 Johnson 8hp.mp4.mp4that for some reason won't rev past idle. I've done a carb kit on it which made no difference. It idle's beautifully but as soon as you move the throttle past idle it tries to rev but then cuts back. Not sure I have explained this well but have attached a video of whats happening. In the video it sounds like I am moving the throttle back and forward but I'm not. Any suggestions on what to look at next would be appreciated.

 

[racerone]

Use timing light and look for intermittent spark.

 

[boobie]

Do a cylinder drop test on it when it's acting up.

 

[oldboat1]

Try adjusting mixture needle (top rear of carb). Turn counter clockwise 1/8 turn at a time and wait a few seconds. Repeat if engine does not smooth out.

 

[merkdawg0084]

Make sure throttle cam and roller are opening all the way too.