1985 Johnson 20 Electric Start

[allmuckmojo]

Ok, So Ive been trying for the past couple of weeks to get out on the water. Im having big motor issues, the motor was sold to me running, heard it rev and let it run for a few, all was good. I get home and a couple days later test it out and after about 5 minutes on choke, i turn it off and the motor bogs and shuts off. I rebuilt the carbs, i did not do an overnight soak but i was very thorough cleaning with a single wire/air gun/good carb cleaner. I can keep it running by playing with the throttle but as soon as i release it bogs down. I re-adjusted the low speed needle w/ dealer recommendation and still nothing.

When I first got the motor I did a compression test and it was good. I changed the water impeller and all seemed to be good to go. I have attached some pictures. If you can see, the top spark plug seems to be surrounded by some MarineTEX or JB weld. I was thinking of the worst but if it was a crack in the block, wouldnt compression be bad? it was 103(t) and 107(b). I looked the part up after taking the plug out and it looks to be cracked on the cylinderhead/water cover. If the gasket were bad and it was cracked there, could it be causing the bogging issue or does that seem to be an issue of its own. and other ideas? i checked out the fuel lines and they dont look gunked up and look fairly new, i removed the gas tank top for ventilation. Hopefully something simple that i overlooked.
:facepalm:

 

[Daviet]

Re: 1985 Johnson 20 Electric Start

You checked compression, did you check the spark, will it jump a 7/16" air gap and is it bright blue?
You can use a timing light to see if you are loosing spark on a cylinder before it stalls.
Was the static setting you used on the low speed needle 1 1/4 turn out from lightly seated?
Have you checked the throttle timing with the mag plate, link & synk?

 

[allmuckmojo]

Re: 1985 Johnson 20 Electric Start

There is spark, did not check the gap it jumped. I had the low speed needle adjusted to 2 1/2 so ill reset that. What is a mag plate , link and synk

You checked compression, did you check the spark, will it jump a 7/16" air gap and is it bright blue?
You can use a timing light to see if you are loosing spark on a cylinder before it stalls.
Was the static setting you used on the low speed needle 1 1/4 turn out from lightly seated?
Have you checked the throttle timing with the mag plate, link & synk?

 

[allmuckmojo]

Re: 1985 Johnson 20 Electric Start

Googles the mag plate, and how to do link and sync, disregard that previous question , lol thanks for the quick response

There is spark, did not check the gap it jumped. I had the low speed needle adjusted to 2 1/2 so ill reset that. What is a mag plate , link and synk

 

[allmuckmojo]

Re: 1985 Johnson 20 Electric Start

Where the cover is epoxied. . . does anyone have any idea if it was letting water by, could it possibly be messing with spark and causing the motor to bog? I would figure that it would do that at high speeds as well if that were the case. Any other information/suggestions would be appreciated

 

[allmuckmojo]

Re: 1985 Johnson 20 Electric Start

I checked spark and spark gape, all was fine. Set the low speed needle back to what was recommended. Started right up no problem, after 1 min lowered the choke. She ran pretty for 4 minutes and then she started to die down. I decided that I would clear the JB weld/epoxy from the cylcase cover (water cover) After pulling the cover off i noticed that the thermostat looked nasty so i popped it off and it was a little clogged (would this cause my stalling problem?) I went to seat the plug back in so I could clear some stuff off without anything falling into the hole, when i pulled the motor. I pulled what looked to be a makeshift thread. I guess the previous owner had striped the original plug threads so they had it machined so that they could screw in a new piece that the plug could fit. I think any additional gaps is the reason that the epoxy was there, not positive because the compression was fine. I decided to pull the head off to check additional damage. Why is it that one chamber is clean and the other is dirty? Anyone ever deal with anything like this?

 

[Daviet]

Re: 1985 Johnson 20 Electric Start

Usually when one cylinder is clean like that it is an indication of water getting into the cylinder.

 

[allmuckmojo]

Re: 1985 Johnson 20 Electric Start

I bought a used head and replaced it, still having issues, i have posted another thread for that separate issue, thanks for all the help