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Johnson 20hp dropping one cyl when warm

F

fredbriggs

Member
I have a 82 20hp electric start tiller steer Johnson that drops a cylinder #2 after a couple of minutes,. no spark at all. Has new coils just wondering due to cost has anyone heard of a stator actually causing only one cylinder to drop out. I personally havent. I have heard of CDI box causing this and will most likely try that first. But big question, is it at all possible for the stator to cause this. Stator is style that is completely coated with plastic, not individual component, what actually tells spark when and what cylinder to fire?
Thanks
 
If the #1 cylinder fire the stator is good ...the stator charges the capacitor in swithbox and timer base tells it to fire. I would inspect plug as it could be: 1) plug 2)switchbox 3) water entering cylinder 4)timer base.....
 
faztbullet said:
If the #1 cylinder fire the stator is good ...the stator charges the capacitor in swithbox and timer base tells it to fire. I would inspect plug as it could be: 1) plug 2)switchbox 3) water entering cylinder 4)timer base.....
Click to expand...
Just to add...I recently was left sit on the river by my 1985 20hp..lost all spark and got an intermittent spark ..Ended up being the ground wire on the CDI where the bolt holds it to the block.Looked ok, but had no continuity from the wire terminal to the block.
 
So if I understand this correctly, there is only one trigger under flywheel and if I never loose spark on #1 and loose spark on #2 once warm, has new plugs, wires, coils, so what tells the spark to fire at the correct time on each cyl? When you talk about the switch box are you talking about the CDI box. I have had all kinds of snowmobiles only fire on one cyl and many times it is the CDI ign box that is failed. How does this engine know when too fire on what cylinder. Runs great first thing when cold? Where is the timer base located and how does it work as far as when to fire?
Thanks
 
It is my understanding the magnets in the flywheel are opposite in polarity do you have a loose magnet in the flywheel? Does the plate under the flywheel have any wiggle up and down? Do you have the proper air gap on the trigger? Sounds to me like the pack if failing swap the coils and see if it follows the coil if it stays the same the PP probably needs replaced.
 
That was exactly my next move. like you say if the problem stays the same and still loose #2 coil then it almost has to be the Power Pack.
Thanks
 
Thanks for the help I still would love to know just how exactly happens to make spark fire exactly on compression stroke on these engines. On all the two stroke engines I have every worked on previously spark happens on each cylinder exactly the same on compression stroke it doesnt matter if piston is on comp or exhaust. Yet I know from experience these engines must have the correct firing order or they are 180 degrees off. I have an old tech manual and can not find anywhere the explanation of firing order? Any help from any subscriber would be appreciated.
Thanks
 
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