Baking a Coil

[mikem]

I have a XL12 w/ no fire to the plug. So I swapped an ignition module from SXL into the XL12 and it fires off. The previous owner said the saw had fire before he pressure washed it During research to find out how to test the ignition module...I ran across a thread that recommending baking the coil in a 200 degree oven for a couple hours to remove moisture. Does this even sound feasible

Second question: If I test the coil and find it defective....how does it come off the ignition plate ? Looks to me like it is permanantly mounted to the plate. Seems easier to just get another ignition module for a few more bucks than a coil.

[MCS]

Is this a breaker point ignition with a coil? The term "module" usually means a blue solid state ignition. Since I think I know where you got the test coil, it is breaker point.
The wire that is used to make a coil is coated with an insulation. It is wrapped in a coil and then sealed up with what ever the black stuff is. If the black stuff is cracked and the coil has gotten wet, is shouldn't matter because the wire is insulated. You say the saw got pressured washed. I'd be more suspect of the kill switch being full of water and keeping the coil grounded. Did you try running it with the switch unplugged? Also, check the wire from the coil to the points and make sure it isn't soaking wet or frayed.
The coil should come off the core by removing the coil ground screw and pulling the little tab of flat metal out. It goes out the flywheel side of the core.
Did you try my ignition testing in the Tutorials ?

[mikem]

Craig,

It is a breaker point ignition with a coil. I called it a "module" to mean the whole assembly. The saw fires with the whole assembly(points,condenser and coil) moved from the SXL to the XL12. Disconnecting the kill switch was the first thing I tried...no change. I put an O-meter on the switch and it tested OK. I printed your tutorial on testing coils and will report results later today.

BTW.....Happy Fathers Day All !!!

[mikem]

Update:

I tested the ignition assembly off the saw, meaning the switch is disconnected & using Craig's tutorial. Following are results:
1) The secondary side of the coil tested at 6,880 OHMS. Not perfect but good.

2) The primary side of the coil tests at .5 OHMS with the points open or closed. I think this is my problem.

3) Points test good.

4) Condenser ramps up then goes to Infinity. Good condenser I think.

Conclusion: The primary side of the coil is bad requiring a coil replacement. Am I wrong ?

[MCS]

Sure looks like the coil is bad. Since you're using a digital meter, your reading for the primary is low. The SXL coil should be the same if you want to compare readings. Did you inspect the wire from the coil to the points for any fraying? The correct routing of this wire is to pass under the tab cast into the breaker box (module base). If this wire is grounded, you will see the same reading you measured. Did you see how to remove the coil from the core? One other thing, if the points are clean, you should see a reading closer to 0 ohms when the points are closed.
Update:
I went out and pulled the rewind from a XL-12 with a Wico ignition.
Readings:
Secondary = 6.8K ohms
Primary measuring from the switch terminal on the coil to coil ground - points open=1.0 ohms and closed .3 ohms.
This is a dirty old saw that I picked up at a second hand store and hasn't had any work done on it. It runs if primed (fuel filter bad) so I know the ignition works.

[mikem]

Jun 21, 2009 13:09:29 GMT -5 MCS said:

Sure looks like the coil is bad. Since you're using a digital meter, your reading for the primary is low. The SXL coil should be the same if you want to compare readings. Did you inspect the wire from the coil to the points for any fraying? The correct routing of this wire is to pass under the tab cast into the breaker box (module base). If this wire is grounded, you will see the same reading you measured. Did you see how to remove the coil from the core? One other thing, if the points are clean, you should see a reading closer to 0 ohms when the points are closed.

Thanks Craig..

I will compare readings with the SXL coil later today. Yes, I got the coil off the core & inspected the wire where it runs under the tab and there was no fraying. The points were corroded initially...I thought that was the problem. I gently cleaned them with 600 grit sandpaper then wiped clean with cardboard and alchohol before the OHM test. I tested the points seperately...they OHM'd at 0 when closed and "open" when the point contacts are open.