and turns the IC igniter off. The sudden
stoppage of current through the ignitior coil
primary winding causes the magnetic field to
collapse. When this occurs, a very high voltage
(up to about 20,000 volts) is induced in the
secondary winding of the ignition coil. This
high voltage is sufficient to jump the gap at the
spark plug. causing the plug to fire.
See Contact Breaker Points in Chapter Three
for point and condenser inspection,
adjustment, and replacement.
See Spark Plugs in Chapter Three for regular
inspection and adjustment of spark plugs.
A resistor-type spark plug cap is used on U.S.
models to reduce radio interference (Figure
10). If you have a high-speed misfire, check the
resistance between the plug terminal and the
plug wire spike. Normal resistance is about
10,000 ohms. If resistance is more than 20,000
ohms, the cap is faulty and should be replaced.
2. Carbon resistor
5. Spring clip
6. Plug terminal
If you suspect that 2 of the spark plugs are
failing to fire or are delivering weak sparks.
check them as follows:
1. Remove the spark plugs from the engine
and compare them to the spark plug chart in
2. I f visual inspection shows that one or both
of the spark plugs are defective. discard them
and install new ones.
3. Check both spark plugs (whether new or
used) by putting on their spark plug wires and
taping them to the cylinder head fins, so that
metal touches metal.
4. Wheel the motorcycle over to a dark corner.
Turn on the ignition. operate the starter and
observe the sparks. If the plugs throw sparks
that are intermittent, feeble or orange-yellow in
color and that d o not make snapping sounds
when they jump, the sparks are weak.
5. If one or both of the spark plugs throwing
weak sparks are old, fit new plugs to the spark
plug wires and observe the sparks again. Watch
also for arcing outside the spark plug cap.
6. If the used spark plugs fail to fire or generate
weak sparks and if the new spark plugs throw
strong sparks (bluish in color, accompanied by
a snapping sound), then one or both of the old
spark plugs are defective.
The ignition advance mechanism advances
the ignition (fires the spark plugs sooner) as
engine speed increases. If it does not advance
smoothly, the ignition timing will be incorrect
at high engine rpm. The advancer must be
lubricated periodically to make certain it
The ignition advance mechanism is bolted
to the right-hand end of the crankshaft, under
the timing cover.
1. Remove the 2 timing cover screws and the
cover and gasket (Figure 11).
2. Remove the 3 timing plate screws and the
plate (Figure 12).
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