Electronic Ignition System; Cdi Module Operation (Aluminum Flywheel); Idi Module Operation (Cast Iron Flywheel); Ignition System Components - Kohler XT-6 Service Manual

ELECTRONIC IGNITION SYSTEM

These engines are equipped with dependable solid-state magneto ignition systems. Two types of ignition modules are
used on these engines, capacitive discharge ignition (CDI), and inductive discharge ignition (IDI).
Both ignition systems are designed to be trouble free for life of engine. Other than periodically checking/replacing
spark plugs, no maintenance or timing adjustments are necessary or possible. Mechanical systems do occasionally
fail or break down. Refer to Troubleshooting to determine root of a reported problem.
Reported ignition problems are most often due to poor connections. Before beginning test procedure, check all
external wiring. Be certain all ignition-related wires are connected, including spark plug leads. Be certain all terminal
connections fit snugly. Make sure ignition switch is in run position.

CDI Module Operation (aluminum flywheel)

Ignition System Components

J
A
B
Kill Switch/
A Off Position of
Key Switch
C Magnet
E Lamination
G
Spark Plug
I Spark Plug Terminal
As flywheel rotates and magnet passes CDI ignition
module, magnetic field induces current in charging coil.
Current pulse is rectified by a diode and this signal
charges a high-voltage capacitor. As magnet completes
its pass, a change in polarity of signal produced by
flywheel magnet turns on semiconductor switch, and
directly connects charged capacitor to primary coil of
transformer. As capacitor discharges energy, low voltage
at primary winding is transformed to high voltage in
secondary winding of module. A high voltage pulse
is then delivered to spark plug, where it arcs across
electrode gap and ignites fuel in combustion chamber.
This system consists of following components:
● Magnets, permanently affixed to flywheel.
● Spark plug with rubber boot.
● Electronic, capacitive discharge ignition module
mounted on engine crankcase.
● Kill switch (or key switch); grounds module to stop
engine.
14 690 01 Rev. G
H
G
F
E
D
C
B Flywheel
D Ignition Module
F Kill Terminal
H
Spark Plug Boot
Air Gap
J
0.254 mm (0.010 in.)

IDI Module Operation (cast iron flywheel)

Ignition System Components
I
A
Kill Switch/
A Off Position of
Key Switch
C Magnet
E Lamination
G Spark Plug
I Spark Plug Terminal
As flywheel rotates and magnet passes IDI ignition
module, magnetic field induces current in primary
coil. As ignition magnet completes its pass, it induces
current in a small triggering coil, which then turns on a
semiconductor switch. This causes previously induced
magnetic field in primary coil to collapse. As magnetic
field collapses, it causes voltage in secondary coil to
rise quickly. This sharp rise in voltage is sufficient to
arc across spark plug's gap, and ignite fuel mixture in
combustion chamber. This system consists of following
components:
● Magnets, permanently affixed to flywheel.
● Spark plug with metal boot.
● Electronic, inductive discharge ignition module
mounted on engine crankcase.
● Kill switch (or key switch); grounds module to stop
engine.
KohlerEngines.com
Electrical System
H
J
E
D
C
B
B
D Ignition Module
F Kill Terminal
H Spark Plug Boot
J
0.254 mm (0.010 in.)
G
I
F
Flywheel
Air Gap
29