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How Do Points Work?-- No Spark!
I am going to
tell you only what you need to know to check your system,
not explain the whole theory of the system. There are a few parts
to the system. 1. points, 2. condenser, 3. charge
coil, 4. ignition coil, 5. flywheel magnets, 6. cam
lobe
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The points are a switch that
when opened cause the ignition
coil to fire the spark plug. This only happens if the "points",
the
smooth contact pads that touch together, are clean as to make a
good
connection when closed. There is a cam, that turns with the engine,
that
opens the points just before the piston gets to top dead center. When
the
points crack open, the spark plug will fire. The ignition coil gets
power
from the " charge " coil. mounted under the flywheel. As the engine
turns
over, the flywheel magnet produces electricity with the charge
coil.
One end of the charge coil must be grounded. Some are grounded through
a tail lamp bulb, if bulb burns out there is no spark. Most are
grounded
directly to the stator "point" plate. From the other end of the charge
coil, power goes to the ignition coil, points, and condenser.
The condenser must be grounded. The other end of
the ignition coil must be grounded. The spark plug lead
comes
off the ignition coil and goes to the spark plug, the spark plug also
must
be grounded.
If you
have battery ignition, then when the ignition switch is on you have
power
to the points even though the engine is not turning over. You can open
the points with a screwdriver, they will spark the spark plug every
time
you open them.
**TIMING**: On the flywheel and crankcase there will be a set
of marks for timing.
Most times it will be a F mark for fire, and a T mark for top dead
center.
When turning the engine, the points should just crack open as the F
mark
lines up with the mark in the case.
When checking for no
spark, bear in mind that most times it is caused by
dirt or corrosion on the contact surface of the ignition
points.
Ignition coils rarely fail, and if a condenser is bad you will get a
tit
built up on one of the point contacts and a pit on the other.
Also
check that the pivot for the points is not sticking, so they do not
close
properly.
There should
be a small amount of grease on the cam lobe that opens the points to
prevent
the rubbing block from being worn down Most points will work set
at about 16 to 18 thousandths.
If you are trying to clean
points, use a very fine sandpaper and clean well after to get all
the dirt and grit out. Any piece of paper or lint caught between will
cause
a no spark. |
Scooter Therapy Inc
12 North Few
Street | Madison,
WI
53703
toll
free
1-800-411-1543
| local
1-608-255-1520
fax
1-608-255-1587 | E-mail
|
Scooter Therapy
Inc
12 N. Few
St
Madison, WI
53703
toll
free 1-800-411-1543
local
1-608-255-1520
fax
1-608-255-1587
E-mail
Hours: M-F,
9-6 Saturday, 10-3 CST
copyright
(c)
2000
Scooter Therapy
inc.
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