Service Manual

Part Numbers
KH10321
Purpose
The coil boosts voltage from around 12 volts to in excess of 20,000 volts.
How It Works
The coil is actually two separate coils of wire wrapped around a common
iron core. One coil, the primary, has fewer windings and thicker wire. The
other coil, the secondary, has many windings, and uses a much finer wire.
With this arrangement, whenever a small voltage change is made to the pri-
mary, a large voltage change results in the secondary. There is a catch,
though. The coil can only produce large “spikes” in the secondary when
there is a rapid change in the primary.
Therefore, the coil relies on the trigger module (packed inside the coil) to
produce this change by quickly opening the primary circuit at the precise
moment the tests are supposed to fire.
Testing
1. If no spark is present, verify that the flywheel magnet is OK by holding a
flat bladed screwdriver about 1/4", from the magnet. It should be
drawn in. Also verify that the air gap is set at .012" to .016".
2. Test the resistance of the primary winding by connecting an ohmmeter
across the kill lead and the core. The resistance should read between
1 and 1.3 ohms.
3. Check the resistance of the secondary coil by connecting one VOM
lead to the spark plug wire and the other lead to the core. The
resistance should read between 7900 and 10,850 ohms.
4. If either of the above readings were out of specification, replace the coil.
Caution: Do NOT connect 12 volt to the ignition coil as it will damage the
trigger module.
Part Numbers
NN10730
Purpose
The coil boosts voltage from around 12 volts to in excess of 20,000 volts.
How It Works
The coil is actually two separate coils of wire wrapped around a common
iron core. One coil, the primary, has fewer windings and thicker wire. The
other coil, the secondary, has many windings and uses a much finer wire.
With this arrangement, whenever a small voltage change is made to the pri-
mary, a large voltage change results in the secondary. There is a catch,
though. The coil can only produce large “spikes” in the secondary when
there is a rapid change in the primary.
Therefore, the coil relies on the trigger module (packed inside the coil) to
produce this change by quickly opening the primary circuit at the precise
moment the plug is supposed to fire.
Testing
1. Verify that the air gap is .020".
2. Disconnect the kill wire and the spark plug connectors.
3. Check the primary coil resistance by measuring across the kill wire and
the core. The resistance should be 1.0 ohms.
4. Check the secondary coil resistance by placing on the spark plug cable
and the core. You should get approximately 9,500 ohms. If either meas-
urement is out of specification, replace the coil.
Coil
Ignition
(Kohler)
Coil
Ignition
Ignition Coil
Ignition Coil
Glossary
GLOSSARY
Demystification Guide 3-7