On Sat, 1 Sep 2012 12:57:03 -0700 (PDT), klem kedidelhopper
wrote:

Someone gave us this non working self propelled mower that he says
just stopped working. When my son first tried to start it he says that
it would run for a few seconds and then quit. After this it would
apparently take about 20 minutes before it would again start, and
again run for about two seconds and then the process was repeated.
This morning we worked on it a little and I could not get it started
at all. We ultimately found that there was no spark. I don't know what
happened when he worked on it. The ignition kill switch is working,
There is no short on that terminal in "run" position, the rust has
been cleaned off both the rotor and stator areas of the flywheel and
transformer and the plug of course looks OK too. There are no points
or capacitor on this mower and there is just a magnet on the
flywheel.The coil has a secondary wire to the plug, a terminal that is
grounded to the transformer laminations with a self taping screw, and
a terminal connected to the kill switch. Unless I'm missing something
the operation of this system seems pretty cut and dried without
timing or anything else being an issue, that as the magnet passes by
the coil a voltage should be induced into the secondary. Am I correct
in this assumption? Is there a way the positively bench test this coil
before we go out a buy a new one that will no doubt be non returnable
if it's not needed? Thanks, Lenny
It's been a long time since I worked on lawn mower engines, but every
one I ever saw had points and a capacitor. On vertical shaft engines
they were typically under a cover under the flywheel. Now I will
admit that this experience was well before the wide spread use of
solid state devices, but there MUST be some method of interupting the
primary circuit as the crankshaft nears top dead center. Also, the
presence of a capacitor is pretty well mandatory.

PlainBill