1985 6 hp Johnson bogging on top end

[rdmotors]

Ok guys this is one to kick around.

Motor got swamped and then "cleaned" out and then run. The carb clogged up and it was brought to me. I have cleaned the carb, installed new impeller, new fuel lines, and put a kit in the fuel pump. Motor started and ran fine from there, never did check top end running at that point. Guy took it back and ran it but top end it would "lay over" and die. I have once again clean the bad gas problem out of the carb, he ran last years gas in it, ran it and found it bogging on top end. So I tried my gas tank that has run other motors with no problems, new coils, new control box, new trigger, and found the charge coil bad ....replaced it with a good one. Even went as far as rejetting the carb to a 8hp jet. I changed all of this in steps to see in anyone thing would fix it. Still no go on top end.

So my thinking is reed valve since it is like the motor doesnt breath on top end. Looking down the intake the top right seems to be off the plate maybe .10 of an inch, but you know how hard it is to see that. Just wondering if anyone has run into anything like this, a swamped motor that had messed a reed valve up. Or any other ideas.

 

[Bosunsmate]

Re: 1985 6 hp Johnson bogging on top end

Are both plugs even looking?
Theres a screen and checkvalve out of sight (again!)at lower end between manifold intake and leaf plate

 

[rdmotors]

Re: 1985 6 hp Johnson bogging on top end

Are both plugs even looking?
Theres a screen and checkvalve out of sight (again!)at lower end between manifold intake and leaf plate

Thanks for the answer I really apperciate it.
Had not checked the plugs since they where new at tune up.....but wait.

Ok the top plug is showing signs of carbon build up on the tang towards the top of the piston.
The bottom looks clean, so that means the top is rich and the bottom is lean?
If so then all the re jetting adjusting the butterfly to not open so quickly is making it run rich. On the top.
Does smoke a little.

If it is the check valve and screen problem I guess the only way to confirm is pulling the intake off.
If we decide to do that, to pull the plate, we should also check reed valves while we are there.

 

[nwcove]

Re: 1985 6 hp Johnson bogging on top end

you adjusted the throttle cam so the throttle wouldnt open as it would normally? i would put the 6hp hs jet back in it, undo whatever you did to the throttle set up, and trouble shoot from the way the motor came from the factory. jmo

 

[rdmotors]

Re: 1985 6 hp Johnson bogging on top end

I hate going behind someone.

Found out the problem...after pulling the carb for the sixth time to reinstall the correct jet. I was just about to give up on the whole thing and just so happen to notice a screw I didnt recognize. Saying to myself that aint stock??? Well it just so happened to be blocking off the bowl vent. Removed that and she revs like it should. It is sometimes just a simple thing....finally found it after a week of trying to fix it.:faint2:

 

[Rick.]

Re: 1985 6 hp Johnson bogging on top end

Perseverance pays off. Glad to here you solved it. Rick..