1985 johnson cam follower adjustment with pic.

[barfly5432]

just bought this motor, 85 rude 15hp and she seems real slow, could this be the reason? I cant find anywhere that states how to adjust.

 

[multimech]

Re: 1985 johnson cam follower adjustment with pic.

It could be a lot of things, specifically about your question. Put the throttle all the way forward and look at the throttle plate. Is it horizontal? If it is you are getting full throttle. Check your timing. Check your fuel (carb clean? pump working?)

Adjusting it is easy. You set your idle timing (don't know it offhand) with the roller cam turning (not against the throttle cam. When you are at full throttle make sure your timing advances to the right timing (again sorry, don't know it off top of my head. Adjust the screw you see on the cam to set idle speed, as long as idle screw on carb is correct ( about a turn and a half)

Hope this helps.

 

[OptsyEagle]

Re: 1985 johnson cam follower adjustment with pic.

As multimech said, if you think that you are not getting full throttle, turn it to wide open throttle, and look and see if the carb butterfly is horizontal. If it is and you are having speed problems, it is something else.

Could be that you are only running on one cylinder. To confirm, run it, let it warm up and at a faster idle with insulated plyers, pull off one spark plug boot at a time. The motor should be able to run with only one cylinder so if it dies when you pull a boot, you will know that the other cylinder was never firing or was very week.

Could be a few other more bizarre things but those are the two I would check first and as always, it never hurts to know the compression numbers at times like these.

 

[gozierdt]

Re: 1985 johnson cam follower adjustment with pic.

That picture looks like it should with the engine at or near full throttle. Just off the
picture to the right, there should be a small raised line on that black cam. The
cam roller should just touch the cam when the throttle plate starts to open. The
small screw just below the roller allows a small amount of adjustment to move the
roller towards or away from the cam, so it touches at the line. But take a look
at the butterfly as suggested above. If it's fully open with the roller in this position,
and the roller is in line as the throttle opens, that's all that you can do.
As above, I'd check both cylinders are firing and then compression. Both cylinders
should be close to each other, and any number above 70 psi or so should run ok. The
higher the better, up to about 125 psi.