Continued mag trouble

PretendFarmer · Jul 14, 2016

MY 1944 H has a Wico XHD magneto. It doesn't run right. When its running, it is only getting spark on cylinder 1 and intermittently on 2 with nothing on cylinders 3 and 4. If I unplug #1, it will then fire normally on cylinders 2,3 and 4.
I've cleaned up the cap. Rotor looks good. Adjusted the points gap to .020". And replaced the condenser with a FM200 condenser from Napa.
It would cost over $200 to have the mag rebuilt. Id rather not spend that kind of money. Any ideas?

PretendFarmer · Jul 14, 2016

Also, I can ground out the #1 wire to the block. I watch it spark to the block and that wont stop 2,3 and 4 from firing. But connecting it to the spark plug will.

Oldiron29 · Jul 14, 2016

set the point gap .013 for mag

PretendFarmer · Jul 14, 2016

I'll try that. And I'll clean them anyways.

Russ from MN · Jul 14, 2016

Spray the cap inside and out with WD-40, and then wipe it off, I'l bet it has small cracks that you can't see, and the spark is being
diverted.

Plant Doc · Jul 14, 2016

I am thinking the same way as Russ. Possible crack in the cap or the cap is carbon tracked. You can spray or clean all you want it will not help. Replace cap and rotor.

gene bender · Jul 14, 2016

Your problem doesnt sound like the mag. Have you removed the plugs and looked at them carefuly. How about wires have you changed them and then mixed them up to se if the bad spark changes to another cycl. same with plugs mixe them up mite want to just do one at a time. I asume you have done a compression check thats also important. You do have spark so the mag is working. I would start with compression check first. Then plugs then wires if conditions are the same it has to be the cap. Just had a Cub they said no power first was compression #1 90 #2 40 #345 #4 80 firing order 1342 so every other cycl had compression in firing order.

PretendFarmer · Jul 14, 2016

(quoted from post at 15:06:58 07/14/16) Your problem doesnt sound like the mag. Have you removed the plugs and looked at them carefuly. How about wires have you changed them and then mixed them up to se if the bad spark changes to another cycl. same with plugs mixe them up mite want to just do one at a time. I asume you have done a compression check thats also important. You do have spark so the mag is working. I would start with compression check first. Then plugs then wires if conditions are the same it has to be the cap. Just had a Cub they said no power first was compression #1 90 #2 40 #345 #4 80 firing order 1342 so every other cycl had compression in firing order.

The tractor(distillate model) has 85psi on all four.
It is not sparking on 3 and 4 when #1 is plugged in. I tried two sets of wires, but I will swap plugs around.

It fires good on #1, and intermittently on #2 with no spark on # or #4.
But if I unplug #1, it will fire normally on #2, #3 and #4. At that point I grounded out #1 and witnessed it sparking to the block. This did not effect its ability to fire on #2, #3, and #4. However when I plug in #1 again, it goes back to only firing on #1, and intermittently on #2 with no spark on #3 or #4.

Really weird.

Janicholson · Jul 14, 2016

Spark voltage always travels to the path of least resistance. If the wires are copper (real wire), and the plugs are OK. the spark is jumping where it does not
belong (probably inside the cap, or internal to the mag coil). Check the conductivity of the plug wires for starting point. All should have zero resistance, No
ohms. Jim

old · Jul 14, 2016

Spray the inside of the cap with starter fluid and let it dry. Then look for any lines on the inside. If you see any lines then th cap is in fact cracked and good chance that is where the problem is

PretendFarmer · Jul 15, 2016

I have ordered a new cap and rotor. At the very least its a good idea because this one looks really beat up.

PretendFarmer · Jul 19, 2016

I replaced the cap and rotor. To my delight it runs normally now. Must have had that carbon cracking everyones talking about.

Continued mag trouble

PretendFarmer

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Oldiron29

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PretendFarmer

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Russ from MN

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Plant Doc

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gene bender

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old

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