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No spark unless magneto touching flywheel magnet

Posted by pppppp (My Page) on
Sun, Jun 8, 14 at 20:34

I have a no spark issue on a B&S 18hp lawn tractor.
It ran fine then shut off.

Once it cooled it started fine and ran until it got hot then shut down again.

It starts cold but wont run warm.
Eventually no spark at all unless the magneto (coil) is touching the flywheel magnet.

With a gap there is no spark but once I set the magneto touching the magnet there is a spark.
Does this mean the coil is bad?


Follow-Up Postings:

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RE: No spark unless magneto touching flywheel magnet

Disconnect the kill wire and see what happens.


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RE: No spark unless magneto touching flywheel magnet

remove the coil to polish any corrosion that may have formed on the screws and mounting posts. See what happens.


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RE: No spark unless magneto touching flywheel magnet

I removed the kill wire and same thing.
I also cleaned the any corrosion on contacts.
still only getting a spark when magneto touches the magnet.
any gap and no spark.


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RE: No spark unless magneto touching flywheel magnet

If it is an opposed twin, these coils fail frequently enough. In general though, if there is no kill wire attached to the coil and magnetism that can grab a screwdriver , you should have spark if the coil was good and the method that you use to determine spark is correct of course.


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