Magneto dead

Thu Jul 16, 2015 8:48 am

Hi Everybody
I need some assistance.
I am restoring my 1947 cub and the magneto has no spark at all.
I have been told it may need to be re-excited.
I have opened it up and cant see anything that looks obviously wrong.
What must I do to put fire back in my cub?
Thanks in advance

Re: Magneto dead

Thu Jul 16, 2015 9:58 am

First, I'd clean the points with an ignition file. Then make sure point gap is set to .013. Make sure when you try the mag that spark has somewhere to go. I install plug and ground plug when I try one.

Re: Magneto dead

Thu Jul 16, 2015 11:24 am

If filing the points don't help I'd bet on the coil . But it could also be your condenser. Make sure your kill switch wire is disconnected and don't get zapped.

Re: Magneto dead

Thu Jul 16, 2015 1:19 pm

There's a wind up shoe under the mag drive hub. This lever winds up the spring in the mag hub releasing it at a higher rpm that makes more spark when starting. Make sure the lever is free so it kicks out to wind up.
It retracks when when the engine is running most mags have them.

Re: Magneto dead

Thu Jul 16, 2015 1:44 pm

In addition to the things mentioned above, I have never heard of a cub magneto needing to be re-excited or re-magnetized. It was common on the old Harleys, and some of the older style magnetos, but on ones of the type used on cubs as well as the letter series tractors, it would be very unusual;

Re: Magneto dead

Thu Jul 16, 2015 2:02 pm

That spring loaded hub if the lever is frozen on the inside it has no spark it can't wind up so it can trip and spin fast.

Make sure the connections are clean in the cap.

Re: Magneto dead

Thu Jul 16, 2015 5:16 pm

Check inside the coil cover clean the connection.

Re: Magneto dead

Thu Jul 16, 2015 6:00 pm

coils go bad in the old mags, take the two screws out that hold the coil in, when you pick up on the coil if its magnetized you will feel the pull of the magnet when trying to remove it so that will answer your question about that

Re: Magneto dead

Thu Jul 16, 2015 6:38 pm

If you need more serious help several of us on the board rebuild these magnetos. Parts are a little pricey, but not ridiculous.

Re: Magneto dead

Thu Jul 16, 2015 6:38 pm

If you need more serious help several of us on the board rebuild these magnetos. Parts are a little pricey, but not ridiculous.

Re: Magneto dead

Tue Jul 28, 2015 1:47 am

Thanks for all the responses.
I found that the spring was broken.
I still have no spark.
I suspect that the coil is dead.
Not sure if I am testing it correctly,the wire to the points is always grounded??

Re: Magneto dead

Tue Jul 28, 2015 3:29 pm

Not trying to hijack your thread, but i am a new member and also am working on an old cub with a mag issue... ive tried my best to do all my homework and have learned alot in the process. i had no spark at the start of my adventure, i cleaned the points off with sandpaper and got a little spark when i turned it by hand. so i followed the spark with a multi meter to the coil and still had spark, put it on the tractor (hand cranking) i had spark on the wire coming out the coil that goes to the dis.and also retested on cyl 4 spark plug wire. now i was testing for Voltage... using a multi meter.. positive in the plug wire negative on the mag body. hand cranking i got voltage shown at the plug.. but when i hooked an actual spark tester to the plug and wire and used the starter i got nothing...??? im lost??? would it have anything to do with me using a 12v battery and switching the terminals?? or only other thing i could think of is the spark not getting from the wire to the engine.. does the housing of the mag need to have a very clean connection to where it attaches to the engine??