Ignition System
69
Troubleshooting the Module
• Normal performance of the coil is to produce at
least 10,000 volts at starter-rope pull-through
speed. See Figure 7.5.
NOTE: Presence or absence of strong spark, with the stop
switch and wire 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: Presence of a weak spark maybe the result of an
improper air gap. The air gap space should be
0.012” - 0.020” (0.3 - 0.5 mm).
NOTE: Simple spark-testers are readily available and
inexpensive. Thexton Part # 404 is available from
a variety of retailers, and similar units are available
form other manufacturers. See Figure 7.6.
• At operating speed, the ignition should produce a
spark approaching 12,000 V. See Figure 7.7.
Figure 7.5
Inexpensive spark gap tester
provides usable information
Figure 7.6
Instructions on
back of package
Figure 7.7
1 reticle = 4,000 Volts
waveform is
3 reticles tall
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