1972 Johnon 100 bogging down

[mfindeisen]

Just got an old Glastron boat with a 1972 Johnson 100 outboard motor on it when my sister and brother-in-law moved to Maine. I guess there aren't any lakes up there. Anyway, it had been broken for some time (throttle switch problem), but we finally got it running. We were out on Lake Travis (near Austin, TX) and skiing, etc., when I turned the motor off. Upon restarting, the motor bogged down, was hard to keep running, and when we would put it in gear it would bog down and cut off when we tried to speed up.<br /><br />We putted along for some time toward the dock in this crippled condition...I thought it might just need to "burn out" something. It got a tad better and then did a few "spurts" of normalcy, which caused us to have hope, but this went on for 5 minutes or so...finally, I pulled the cover and pressed the manual choke switch back and forth. First I killed it, then it started back up and was fine again. Crazy! <br /><br />Got back to the boat ramp, had to wait for the trailer...while waiting, we ran out of gas. I had an extra can, so I filled it up (with my oil) and then started it again...it was back into bogging mode...I tried the choke trick again to no avail. It kept bogging for another 5-10 min, dying every so often, until we trailered it.<br /><br />Got home, read the manual, read multitudes of forum posts, etc. Started it up with the water hose connected to lower unit and the engine sounded good again...no longer bogging down. Very strange. <br /><br />It sounded like the choke was stuck on to me, but I don't know a whole lot about boat engines. When we have the cover off and watch what happens when we choke it from the key box, the little plunger on the choke solenoid goes up and down...doesn't seem to stick, at least mechanically on the outside of the engine.<br /><br />It bogs in neutral and in drive when its bogging, but once its out of bog mode, it runs great. Any ideas? I really don't want to get stuck way out on the lake with this problem.

 

[almost retired again]

Re: 1972 Johnon 100 bogging down

Hi Mike,<br />It kinda sounds like dirty carbs and the only to way clean them is to pull them off, take them apart clean them with a good carb cleaner making sure that the spray passes through all of the openings and passages. Before you do that I would check for spark on all cyls., and do a compression check.<br />Good luck

 

[Captain Haddock]

Re: 1972 Johnon 100 bogging down

Might worth doing anyhow if carbs&compression is ok:

Remove flywheel, remove distributor cap and rotor.
Unassemble points, be careful with the springs, do not bend them permanently out of shape.

Clean&check condition and wear of bushings +points.
Decide if it is time for new points&capacitor.
Apply small drop of oil on pivot pin.

Clean & oil lube-cushion, make sure it pushes against excenter.
Clean & apply _thin_ layer of appropriate grease that stays on when hot&spinning on excenter, reassemble points.

Wipe off any spill, make sure that no oil or grease gets to the points

gap at 0.010", check anti reversing spring . Clean distributor cap and rotor and reassemble....

For spark plugs:
If not alredy fitted, use _only_Champion QL77JC4, or L77JC4 if not the first ones can be obtained.

Good luck