Magneto test

[Anonymous-0]

I have a Wico X magneto i took of my 51 B. it has sat for 27 years since it last ran so i pulled off the carb and mag to clean and work on both. My question is, how do i make a test magneto stand to see if i have spark? i have an idea to make a camshaft to fit into the drive lug on the back of the mag ran by a drill, but how do i ground the set up to make sure it all works properly? Any ideas or suggestions?

 

[Paul from MI]

Clamp it in a vise by the lower mounting lug(NEVER CLAMP AROUND THE BODY OF A MAG!!). Turn it in the operating direction using a crescent wrench on one of the drive lugs. If it's working the impulse will trip and you will get a spark from the wire socket to the body of the mag. It doesn't have to be turned a complete revolution. It should spark when "rocked" back and forth enough to trip the impulse coupling. Just be sure your wire is in the correct wire socket.

 

[Kurt_JDB]

First thing should be to clean and set the points, or put in new points and possibly a new condenser. Also, you might want to put a dab of lubricant on the cam. After 27 years, the points are going to have oxidized and probably won't conduct.

To test for a spark, I usually clamp the mag in a vice by the mounting flange, and put an old spark plug wire in the cap and hold it so the terminal is near the body of the mag or vice. Then I just reach over and turn the lug until it snaps. Wear a pair of gloves.

You might have to get it to snap twice to have it fire at the terminal you have the wire attached to.

It is important to have the mag oriented as it would be on the tractor, or the impulse pawls won't catch as they move into position by gravity. Some say not to fire the mag much unless both terminals can spark to ground as it can damage the coil.

John T will have more to say if he comes by.

Good Luck,

Kurt

 

[John T]

I agree with Paul, you dont need any complex test rig. If you clamp the mag in a a vise in upright normal position and as looking at the impulse drive if you rotate it CCW the dogs should extend out so the spring winds up and then it should trip/snap (each 180) and fire spark plugs with wires to each cap terminal if their sides are grounded to the vise which is obviously also grounded to the mags metal frame. It will fire the plug out say the top cap tower and then another 180 of drive rotation it should fire the plug out of the other bottom terminal. If it were rotated with say a drill at over 250 RPM the impulse stops working and she free runs but still fires every other plug every 180 of rotation.

The points are probably gray oxide coated so clean/buff/polish them and gap at 0.015 and see what happens using plug wires n plugs with plug sides grounded to mags metal case, its NOT good to dry fire them with no plug load.

John T

 

[John T]

Gee our minds must have been connected as we were both typing at the same time lol If theres no plug attached the coil voltage rises much higher then normal and a spark/short may happen in or on the coils outside which can damage the insulation. Some mags have a built in shorting safety gap so that dont happen but NOT Wico C or X

John T