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Re: Cub magneto
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Posted by John C. on November 16, 1999 at 12:16:27 from (12.13.248.14):
In Reply to: Cub magneto posted by Tom Wells on November 16, 1999 at 09:42:01:
When the magneto is rotating at very slow (hand cranking) speeds, part of the rotating mechanism (impulse) "catches" on a stop, and allows a spring to wind up for a few degrees of rotation. Another part of the impulse mechanism hits the catch arm and releases the wound-up spring, giving the magneto rotor a short burst of high rpm, which is usually enough to cause spark and start the engine. When the engine is running, the centrifugal force on the impulse arms causes them to pull in, and they no longer catch on the stop. Examine the drive lug on the magneto and see if the drive lug cup feels like it has a rotational spring inside. Also see if a couple of arms flop out of the drive lug, when you rotate it by hand, with one of the arms momentarily catching on a stop. I had a magneto with a broken impulse stop, and the arms would come out but wouldn't catch on anything. Good luck.
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