1964 Johnson 40HP bucking, misfire, bogging problems...

1964 Johnson Super Sea Horse Electric Start RDSL-26R. Bucking and misfire but continues to run. Engine was sitting for many 15+? years and there is some oxidation on the exterior castings of the engine. So far we have:
Drained all old fuel and mixed fresh 50:1, replaced all fuel lines, cleaned carb (had it off several times to triple, quaddrouple checked the orfices for obstructions, and float adjustment), tested the float, set float adjustment, installed new carb kit (I do have some carb experience), Installed new spark plugs, sparkplug wires, both new sets of points/condensers gapped at .020" , installed both new coils, new neutral saftey switch, tested the thermostat, installed new impeller. I've been running it in a garbage can (with running garden hose) since muffs wont work on this engine. I have not replaced the fuel pump, but it seems to be getting plenty of fuel and I've kept the primer bulb pumped as its running and it isn't making a difference. I've not done a compression test (dont have the tool) but it seems to have great compression. It seems like an ignition issue, but when I choke the carb it runs smoother...possibly hiding the ignition problem.....Any Ideas? At this point I'm beginning to think that it's a crankcase seal or reed valve.....Suggestions welcome..Thanks in advance.

Re: 1964 Johnson 40HP bucking, misfire, bogging problems...

Check to make sure flywheel key is not sheared. Did you actually test spark after replacing everything to make sure it's firing ok? If you don't get the wires properly connected to the coils you may not be getting adequate spark.

Re: 1964 Johnson 40HP bucking, misfire, bogging problems...

The bucking, misfire ("lean sneeze" ?), and better running with the choke on still point to a fuel delivery problem. Check for air leaks in all of the fuel lines/connectors. Did you remove the metal welch plug on the top of the carb (behind the low speed needle) and clean those passages?

The motor also may run like crap in a barrel, since it may be ingesting its own exhaust.

Re: 1964 Johnson 40HP bucking, misfire, bogging problems...

Ok..thanks for the tips. I checked the flywheel key and it's not sheared, then checked the spark while pulling it over by hand; pleanty of nice blue spark that seems to be consistent. The new coils had threaded "spear" type connections that the new spark plug wires were threaded onto for a very secure connection. Next I double checked all fuel lines and connections, they all seem snug and no bubbles are in the fuel line to the carb (it's clear, see thru line). I removed both welch plugs when I rebuilt the carb. Two of the orfices under the top welch plug were plugged, but I cleared that when I cleaned and rebuilt the carb. I'm thinking that I'll be checking the reeds next, then a powerhead removal and possible teardown. (I've got the knowhow and experience in engines, just never did an outboard yet). The "lean sneeze" is the best term I've heard to describe the symptom of the problem. One more thing: I disabled the mechanism that prevents the ignition from fully advancing in neutral and discovered that the engine runs quite a bit better (in neutral with more throttle) now, and when I choke it, it runs even better. Maybe this is another indication of ?...... Any more suggestions? Thanks again for the advice!

Re: 1964 Johnson 40HP bucking, misfire, bogging problems...

I had to remove and clean the carb on my 1959 Johnson 35HP (virtually identical to yours) three times before it would idle properly. However, I think the fuel pump is suspect since it was not touched and you have verified a fuel supply problem by getting it to run better with the choke on. If you need a service manual, I have one scanned and saved that covers your model motor. Send me a Private Message with your email address and I will reply back with the manual as an attachment. Good luck!

Re: 1964 Johnson 40HP bucking, misfire, bogging problems...

pump primer bulb to see if helps.

maybe try a carb adjusting. 1 1/2 out low speed needle. 1 turn out high speed.

Re: 1964 Johnson 40HP bucking, misfire, bogging problems...

http://forums.iboats.com/showthread.php?t=299680

Re: 1964 Johnson 40HP bucking, misfire, bogging problems...

Pulled the powerhead and VERY carefully removed the carbon crankshaft seal: looks good....cleaned and reassembled. Fired it up and observed....ran great for about 30 seconds or so, then buck, sneeze, buck, buck....same old thing. Got fed up....had the carb off a zillion times by this time...could drink fine vintage wine thru it, its so clean. Pulled the flywheel for the umpteenth time... disconnected BOTH kill wires that go from the harness to the points and reassembled. NOW it runs like a 1964 40HP Johnson Super Sea Horse!

Thanks for all the tips and advice! This site takes the wake!


Now I've got to find where the wiring issue/s (going to ground?) is/are in the kill wires and run some NEW wires if needed.. I think I can figure that out.

Thanks again guys!

Re: 1964 Johnson 40HP bucking, misfire, bogging problems...

OK guys, I have the same, sneezing, jerking problem as strato, have done about everything that strato has done up to taking off the flywheel, been afraid to do that LOL. I need info on the flywheel, points, kill switch locations/ wires. My land lord and I have been stroking this old RDS-22 for a couple of weeks now, gave up on it once, but checked the compression and both cylinders have 140 LBs, +/-, Help? godaryl