I have a mag that when I put a neon light tester on it it will light the light on the coil and all 4 plug holes when hand cranking. When I take the plug put and ground it no spark to the plug.I think it is a J4 mag.I don't think the mag is putting out enough power to jump the spark across the gap. Is there anything I can check,clean, adjust or any ideas to try. Thanks for any help.
- Thread starter whig
- Start date
Bill Lisbon
Member
Are you sure your spark plugs are good? Are the plugs gaped to .025? If you have the nerve you could hold on to the plug wire to make sure the mag is working.
Nebraska Cowman
Well-known Member
The spark should jump from the wire to ground 1/4 to 3/8 inch. Throw the light away. Dirty points will be your #1 culprit in poor spark.
DON'T have the B-s for that move. Been there and ain't going back. I did use a new plug. Can I clean the points without taking the mag off? These red tractors are new to me. I have a J,D. 50 and still learning on that one. The cub is my winter project but would like to get running befor tearing it apart. thanks for any response
"If you have the nerve you could hold on to the plug wire to make sure the mag is working."
All I can say is that's a REALLY dumb comment!
You must be a MASOCHIST!
His neon light flashes, so, yes, anyone DUMB enough to hang onto the sparkplug wire is GOING to get a shock!
HOWEVER, there's quite a difference between what will shock a human silly and a good HOT spark to fire a sparkplug!
All I can say is that's a REALLY dumb comment!
You must be a MASOCHIST!
His neon light flashes, so, yes, anyone DUMB enough to hang onto the sparkplug wire is GOING to get a shock!
HOWEVER, there's quite a difference between what will shock a human silly and a good HOT spark to fire a sparkplug!
Thought plugs for a mag were supposede to be gapped at 13, not 25. I could be wrong. been operating one since 1983, family owned sicne 1953, working on one right now. 13 for a mag I thought. will have to check teh book again...
points gaps is also 13. shoudl try to clean teh points with 400 grit or 600 grit sand paper. they will clean up. never had much luck with the j4 starting as good as a batt ig cub, but who knows, might just be me.
Denny ('60 Lo-Boy)
Member
This page from an original '47 Cub owners manual:
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