T
FIGURE 39.. ALIGNING TIMING MARKS
7.
Install ignition breaker points and adjust gap.
Time ignition.
-,
-"
DIAPHRAGM
CUP
FIGURE
40.
BREAKER PLATE ASSEMBLY
Condenser
The .3 mfd condenser mounted on the breaker plate
aids primary field breakdown when the points open
and prolongs the life of the breaker points by
reducing the arc across them. A defective condenser
causes a weak spark and rapid breaker point wear.
Use a standard commercial condenser checker to test
the condenser for leakage, openings or grounding. If
no tester is available, check for shorts or defective
leads and replace the condenser if you suspect
defects.
Coil
If spark is weak or there is no spark, and the breaker
points are clean and properly adjusted, test the coil
for possible defects. Disconnect both spark plug
leads, ground one and hold the other about 3/8 inch
from the engine. Crank the engine.
If
there is a good
spark the coil is operating. Also test the coil as
follows:
1.
2.
Disconnect breaker point lead at breaker points
and measure resistance from that lead to ground.
It should be about one ohm.
Disconnect both spark plug leads at plugs and
measure resistance between them. Resistance
should be between
7000
and
10,000
ohms. If it is
higher, either the high tension terminals or spark
plug leads are defective. Remove leads and check
resistance of coil between hi-tension terminals.
Check terminals for corrosion. Check leads for
resistance. Replace any that show a high
resistance. If resistance
is
low, coil is probably
shorted, and should be replaced.
3.
Check for shorting between primary and secon-
dary coils by checking for continuity between a
primary terminal and secondary terminal.
Test this coil
using
a
six-volt tester
only.
MAGNETO IGNITION
(JB,
Manual Start)
This ignition system is similar to the
JB
battery
ignition except that it uses a magneto as a source of
power. The magneto is behind the flywheel and
consists of both stator and secondary windings,
energized by permanent magnets on the flywheel.
Figure
41
shows the magneto ignition system.
For maintenance, timing, condenser repair, and for
breaker repair, refer to the applicable section in
Battery Ignition.
Magneto Coil:
The magneto coil is located behind the
engine flywheel and reached by removing the
flywheel. If ignition spark at the spark plugs is
defective, first inspect the breaker points.
To
test the
coil, remove both spark plug leads; ground one to
bare engine metal. Hold theotherabout3/8 inch away
from bare metal and crank the engine. A good spark
should occur between the lead and engine. If not, the
coil, flywheel magnets,
or
high tension leads are
defective. Test the coil as follows:
1.
2.
With an ohmmeter, check resistance between
breaker point lead (disconnected from the points)
and a good ground on the engine. Resistance
should be about
0.6
ohms.
Remove both spark plug leads from plugs and
32
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