IGNITION SYSTEM
53
The module
The coil in this ignition system is an inductive dis-
charge magneto, contained in a single module.
• The inductive discharge magneto has a two leg
design.
• The magneto is energized by the passing of a
magnet mounted in the flywheel.
• Ignition timing is set by the location of the fly-
wheel in relation to the crankshaft. Proper timing
is maintained by a steel key.
Normal performance of the coil is to produce at least
10,000 volts at starter-rope pull-through speed.
The presence or absence of strong spark, with the
stop switch known to be good, is generally enough to
identify the ignition coil as good or bad. Resistance
readings may help confirm the source of the failure, but
are generally meaningless because they only measure
a small part of the module.
NOTE: No spark or a weak spark may be the
result of an improper air gap. The air gap space
should be .016”-.024” (0.4-0.6mm).
Simple spark-testers are readily available and inex-
pensive. Thexton Part # 404 is available from a variety
of retailers, and similar tools are available from other
manufacturers.
See Figure 7.10.
NOTE: If the complaint is that the engine quits
running when it gets warm, the ignition module
should be tested with the engine at normal oper
-
ating temperature.
Figure 7.10
Instructions on
back of package
• At operating speed, the ignition should produce
voltage approaching 12,000.
• At pull-over speed (~
600 RPM), voltage should
be at least 10,000V.
NOTE: The voltage required for a flash-over will
vary with spark plug condition and gap.
NOTE: Pull-over speed may vary from operator
to operator.
NOTE: Failure of the magnets in the flywheel is
exceedingly rare. To test the magnets, simply
hold an item made of ferrous metal roughly 1/4”
(.635cm) away from the magnets in the flywheel.
It should be drawn to the flywheel. A wrench or
screwdriver is suitable for this test.
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