Help with my Johnson TD-20

[OMCfan]

I need some help with a TD-20 I am working on. Here is what I know/What I have done:

Good compression, water pump works well, magnet wheel seems strong and I I cleaned the tank out good even though it was actually quite clean looking.
I tested for spark and only had spark in one cylinder so I pulled the flywheel to inspect the coils. To my surprise they looked great-no cracks.
I needed to set the gap for the points at .020 and cleaned the points with 1000 grit wet/dry sandpaper and then ran clean dry paper to finish the cleaning.
After reassembly, I had spark in both cylinders so I added some gas and she started and ran on the third pull and I let it run for over an hour while playing with the needle valves.
I shut the motor down as it was getting low on gas and later added some more and tried to start it up...no go and when I checked I have no spark in either cylinder.
Am I dealing with bad condensers?

 

[gm280]

:welcome: aboard OMCfan. Nice to have you join us...

That is not unusual and equally it could be a few different things as well. I kind of doubt it is the points. And even doubt the condensers as well. But the exciter coil or the spark coils are suspect. If they are original, it may well be either of them. But the fact that you now have no spark in either cylinder, I'd check the exciter coil first. But if you are going back in to the flywheel area again, I would test everything to verify the good from not so good parts...

 

[F_R]

Are we on the same page, gm? This is a TD-20 we are talking about. No "exciter coil". OMC fan, those TD coils were made before OMC found out how to make coils that would crack after 3 years. In other words, almost bulletproof. My suggestion is to take those points out and take them completely apart. Now degrease them and polish each contact individually and reassemble. I'll bet you will get fire. Condensers? Well, after 65 years, all paper condensers will show some leakage. Maybe not ideal, but they will run anyway unless shorted completely.

EDIT: I may be wrong, but I think that one may have a stop switch built into the mag plate. Investigate that if cleaning the points as I described does not work.

 

[OMCfan]

Thanks gm280 and thank you F_R!

I have to believe that the coils are still good. This thing sat in storage for years and honestly I was shocked at how good the coils looked! They are black and intact. I will take out the points and make absolute sure they are clean and well polished. As far as the ignition components, all I did was clean the points and set the point gaps. The thing fired up after the third pull. Will alcohol wipes work for cleaning them after polishing?

 

[F_R]

I've never tried the wipes, so can't answer that one. I just draw a piece of lint-free paper between them as a final step.

 

[OMCfan]

I will have to look for a stop switch on the mag plate I guess. I took the points completely apart. cleaned the points with electronics degreaser and then reinstalled and no luck. Puzzling. On the positive side, I can pretty much get that thing torn down to the ignition in about 5-7 minutes Took out each condenser and both looked to be in very good condition not breaks in the wiring. One thing I would like to know. Should the contacts on the coils be touching the rotating magnet or should there be a slight gap?

Thanks guys!!!

 

[gm280]

I will have to look for a stop switch on the mag plate I guess. I took the points completely apart. cleaned the points with electronics degreaser and then reinstalled and no luck. Puzzling. On the positive side, I can pretty much get that thing torn down to the ignition in about 5-7 minutes Took out each condenser and both looked to be in very good condition not breaks in the wiring. One thing I would like to know. Should the contacts on the coils be touching the rotating magnet or should there be a slight gap?

Thanks guys!!!

There should be no touching between the coils and the magnets. If they are touching, that needs to be fixed. And if you have a meter and know how to use one, do a test across the condensers (capacitors) to verify they are not shorted. That old wouldn't really surprise me. And if you have a really good meter that has a capacitance scale on it, see what they read as well and let us know...

 

[OMCfan]

F_R you were right, there was a stop switch that I found on the mag plate. It has the insulator washed between it and the mag plate and it does not appear to be contacting any part of the mag plate until the throttle lever is moved all the way to the stop position as it should.

gm280 thanks for the advice I adjusted the coils and they are not contacting the magnetic wheel. I am going to assume that I have a bad condenser. So I will try to get replacements and go from there. Sure am learning a lot!!!

 

[OMCfan]

Okay gentlemen, just got back from vacation so here is an update on my problematic TD-20. I have replaced the condensers. Took the points completely apart and cleaned them. set the points at .020 after reinstalling them. I replaced the spark plugs with new ones. The kill switch seems to be operating as it should and I could find no evidence of anything grounding out/arcing in the mag plate. I can pass paper between all areas of the coils and the magnetic wheel. I still did not get any spark.

I am fairly certain the coils are in good shape, but I do not have the means or know how to test them and the local guy here does not work on motors this old and that is probably wise. Any other suggestions before I part this thing out? Thanks for your help though!!!!