MTD Engine - Series 350/450/650
20
7.22. Resistance in the secondary windings of the
ignition module, measured between the spark
plug terminal and the laminations, was observed
to be in the 8K-9KΩ range. See Figure 7.22.
7.23. Failure of the magnets in the flywheel is exceed-
ingly 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.
7.24. An inexpensive compass or bar magnet can be
used to confirm opposite polarity of the flywheel
magnets. See Figure 7.24.
7.25. Spark plug: refer to steps 5.2 through 5.4 in the
MAINTENANCE AND ADJUSTMENT INFOR-
MATION section of this manual.
NOTE: There may be slight variation in specifi-
cation due to production variation and other fac-
tors such as temperature.
• Resistance figures that are vastly lower may
indicate a short in the windings being tested.
• Resistance figures that are vastly higher (or O.L)
may indicate a fault in the windings being tested.
NOTE: Intermittent failure requires tests for volt-
age and resistance to be made when the engine
is cold, and again when it is hot.
• Typical customer complaint: “It stops after I mow
for 10 minutes and I can’t get it to re-start”.
• To confirm that the problem is ignition-based, it
is necessary to “catch it in the act”.
• Resistance normally rises as temperature
increases.
Figure 7.22
Probe to spark
plug terminal
Probe to laminations
Figure 7.24
Opposite poles of bar magnets
are attracted to opposite pole
flywheel magnets for the sake
of illustration
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