Johnson 50hp throttle linkage?

Bushleague

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I have a 2001 johnson 50hp that has been running like crap. Cleaned out the carbs, and did a bunch of the ususal checks with no improvement. Anyhow, in the trouble shooting process I got around to noticing my throttle linkage was way out of spec so I decided to fix that and see if it made any difference...

So here is the current problem I'm fighting with, the timing advance controll rod is supposed to be set at 2 1/16" long; First off mine will not actually go that short 2 1/4" is as short as I can get without modifying it. And now we get to the second problem, with the controll rod set anywhere near 2 1/4", the timing advance hits the end of its travel and binds up the "cam slot" in the main linkage piece, so that the throttle can not continue to open up. Hoping that makes sense, I'm assuming this was why the controll rod was set way longer than spec in the first place.

So my question is what do I do now? About all I can think of is to set the controll rod as short as possible and then attempt to adjust the stop bolt to set the timing, and adjust the throttle controll rod to whatever length needed to accomidate everything else being out to lunch, which is what I'm assuming was how it was setup in the first place. If anyone has any suggestions though, I'm all ears.
 

mturner125

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On the timing advance - The service manual for my evinrude 50 suggests you're to measure from the center of the socket to the other center of the socket. Is that how you're measuring?
 

Bushleague

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On the timing advance - The service manual for my evinrude 50 suggests you're to measure from the center of the socket to the other center of the socket. Is that how you're measuring?
Yep, measured C-C. I re-bastardized the whole thing and its now running exactly as badly as it was before I started messing with the linkage, so I guess thats a small win.
 

oldboat1

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When you did that bunch of usual checks, did you measure spark on each lead. Need an open air, adjustable tester (auto parts store).
 

mturner125

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I'd start by resetting all the linkages to the factory recommendation.
Next step would be to verify compression on all cylinders.
Then verify spark jumps 7/16" gap with a tester (15 bucks on amazon). If all is well with spark and compression I'd then focus on fuel delivery and the carbs.

Is it running badly at all RPMs or just idle?
 

Bushleague

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I'd start by resetting all the linkages to the factory recommendation.
Next step would be to verify compression on all cylinders.
Then verify spark jumps 7/16" gap with a tester (15 bucks on amazon). If all is well with spark and compression I'd then focus on fuel delivery and the carbs.

Is it running badly at all RPMs or just idle?
Just running badly at idle, I cant set the linkages to the factory recomendations. Compression has been verified. I only visually tested spark, never used a spark tester before, guess I'll have to get one.
 

mturner125

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Just running badly at idle, I cant set the linkages to the factory recomendations. Compression has been verified. I only visually tested spark, never used a spark tester before, guess I'll have to get one.
Yeah, it's low cost and you'll be able to rule that out as the culprit. If you have compression and spark, it seems like fuel delivery would be next on the list to check. I'd remove the air silencer and have a friend at the controls keeping the motor as close to idle as possible. You can then place your hand up to each carb throat to feel the air passing through. If the motor sputters as you begin to cover the throat of the carb with your hand you'll know it's firing. You may have a situation where the top or bottom isn't firing. Could be a bad reed or vacuum leak.
 

Bushleague

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Yeah, it's low cost and you'll be able to rule that out as the culprit. If you have compression and spark, it seems like fuel delivery would be next on the list to check. I'd remove the air silencer and have a friend at the controls keeping the motor as close to idle as possible. You can then place your hand up to each carb throat to feel the air passing through. If the motor sputters as you begin to cover the throat of the carb with your hand you'll know it's firing. You may have a situation where the top or bottom isn't firing. Could be a bad reed or vacuum leak.
Yeah I'm starting to wonder about the reeds, I have already pulled the carbs and cleaned them, all the jets looked pretty good to begin with and the clean out accomplished nothing.

If I dissconect the sparkplug lead to the top cylinder the engine will idle on just the bottom cylinder just fine. Doing the reverse however, it will only idle for a little bit on the top cylinder and then die. Not sure if that is normal. On the top carb however I can pull the top plate off and visually see that the idle circuit is still clean as a whistle, so I dont know if another carb clean out will do anything for me. Could this possibly indicate I should be looking at my reeds?

When the problem started it was really suddenly, I was trolling allong for about 45 minuets just fine, then just like flicking a light switch it wouldnt idle properly anymore. My first inclination was to think it was a spark issue or a plugged idle jet, but as I said, spark looks good visually and carbs seem fine.
 
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jakedaawg

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After the compression and spark tests you might verify that the timing cam roller has both layers on it. The outer layer cracks and falls off. They dont idle well when that happens.
 

mturner125

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Yeah I'm starting to wonder about the reeds, I have already pulled the carbs and cleaned them, all the jets looked pretty good to begin with and the clean out accomplished nothing.

If I dissconect the sparkplug lead to the top cylinder the engine will idle on just the bottom cylinder just fine. Doing the reverse however, it will only idle for a little bit on the top cylinder and then die. Not sure if that is normal. On the top carb however I can pull the top plate off and visually see that the idle circuit is still clean as a whistle, so I dont know if another carb clean out will do anything for me. Could this possibly indicate I should be looking at my reeds?

When the problem started it was really suddenly, I was trolling allong for about 45 minuets just fine, then just like flicking a light switch it wouldnt idle properly anymore. My first inclination was to think it was a spark issue or a plugged idle jet, but as I said, spark looks good visually and carbs seem fine.

I think we're chasing down similar issues with our motors. Mine runs fantastic above 1500 rpm. The bottom cylinder is the problem for me at idle. I expect the process for inspecting the reeds will be the same on your motor. It's fairly easy - you pull the carbs and then the intake manifold. Remove the gasket that's laid in dry and you can pull out the top and bottom reeds. Mine looked perfect w/o any chips or cracks. Jose Extreme DIY on youtube has a good video up showing the process on his 40hp. I held them up to the sky and could not see any light coming through the edges. Spent the 15 dollars or so on a new gasket and put the air manifold back on, torqueing the bolts per the manual spec.

Maybe two weeks ago I installed a new carb kit on the bottom carb and it ran really well that day, even at idle. When I installed the kit I made sure to press in the copper nipple on top of the carb that accept the fuel line coming from the primer solenoid. It's a long shot but I'm going to inspect that line and the connections to the solenoid next time I'm on the boat. My theory is that I might be getting a bit of air leakage and that may be taking suction away from the idle circuit.
 

racerone

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It should keep running / idling on the top cylinder if lower plug lead is off !!
 

mturner125

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It should keep running / idling on the top cylinder if lower plug lead is off !!

Hey Racerone - What should the quality of the idle be like on one cylinder? Mine kinda barely hangs on with only the top cylinder firing at idle. The motor might be at 550-600 rpm and it will almost always shut down as I try to engage the forward gear. Is that pretty typical?
 
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