How to check a mag without it being on a tractor?.

1. One way with the cap still on, is to use a good plug wire and a good spark plug and with the plugs side steel frame up against the metal part of the mag, turn the mag and when the srping snaps over, the plug should produce a spark. If your looking at the rear of the mag, it would be turning its coupler CCW which winds up the spring and then it should snap over and fire the plug. Both terminals should fire the plug, one on the first snap over and then the other trminal shouuld fire the next time.

2. If neither terminal will fire a [plug, it could be a spring and trip assembly problem, becasue it has to be fairly hard to wind up and then release rapidly. If turnign it feels easy and it doesnt seem to wind and trip a srping, its not correct and wont work.

3. Its possible the mags points and condensor and coil could be good and it still fires, but wont fire out through the plug wire terminal. That could be caused by a bad cap or rotor. To check that, remove the cap and rotor, and attach a wire to the mags steel frame and then to within about 1/8 inch away from the little steel button on the side of the coil where the caps spring fits. Thats the coils high voltage output. Then, when you wind and trip the spring, a spark should jump between the wires end and that coil output button.

4. If she wont fire there or anywhere and the spring and trip are okay, it could be bad points or coil or condensor or a short. The points need to be gapped at 0.015 and clean and free of any pits or burns or corrosion or bad oxide coating.

Hope this is some help as to how to test it both out the plug wire terminals and the coil itself. If you have any more questions, post back and let us all know what you found out and we will try and get you going.

Good Luck n God Bless

Ol John T Nordhoff in Indiana

~The above holds true for the Wico C & X & most mags but if by chance you have a different type or a gear drive mag, post back as it could be a little different.

~Keep in mind the above test just shows if the mag produces a spark that will run the tractor, it doesn't show if the mag has the correct lag timing, bad oil seals, or worn shaft & bushings. [important for long term reliability].

~If you don't get a blue spark to jump that wire to case 1/8"-3/16" gap, post back & give us the mag model & what it is or isn't doing & we will try to furnish places to check for no spark condition.

Someone will no doubt jump in here with more information, but until then, yes, you can check the mag while it is off of the tractor.

If you have an operator's manual, the procedure is described in there.

Basically, after setting the points correctly, you clamp the lower mounting lug of the mag in a soft-jawed vise. then you put a wire in one of the plug wire holes (top is fine), and bend the wire around until it is about 1/4" away from the mag frame. Then you slowly turn the mag in the running direction, and when you get the drive lug almost to the horizontal, the impulse spring will trip, the mag will go "snap !", and it should spark.

I purposely did not tell you which direction to turn the mag, as I only THINK I remember that it is counter-clockwise when viewed from behind (pretty sure I'm right there, though). But the best way to know is to have someone else here tell you, or move the engine a bit in the running direction (top of the flywheel forward), and note the direction that the governor drive lug turned. Turn the mag in the same direction.

Oh, and don't get yourself between the wire and mag frame....just in case it's working well !!

Hope that helps.

Frank-in-Tallahassee
70D // 855