5-4 ELECTRONIC IGNITION SYSTEM
The electronic ignition system features a power transistor as the current control element. Therefore, the igni-
tion system is an electronic contact point-free type that operates with the power transistor impulses control-
ling the current. This system is also called TIC (transistor igniter circuit) and is virtually free of ignition fail-
ure which generally results from contamination of the contact points, a typical problem with contact type
ignition systems.
Because this ignition system has no contact points, it is not affected by moisture, oil, dust, or other contami-
nants. As a result, this electronic ignition system ensures sure and positive ignition with reduced maintenance.
The TIC mechanism consists of a transistor-incorporated ignition coil and a permanent magneto built-in fly-
wheel which is press-fitted on the rotor shaft of the generator.
I
IGNITION COIL
IGNITION
TIMING
DETECTING
CIRCUIT
SPARK PLUG
Fig. 5- 70
(1) When the permanenet magneto built-in flywheel starts rotating, power is generated in the primary coil of
of the ignition coil and current flows to the resistor @ .
From the resistor, current flows to the power transistor. With this current, the power transistor turns on,
releasing current @ . This stage corresponds to the closing of contact points.
(2) As the flywheel comes to the point of ignition, the ignition timing detecting circuit is activated while the
current @ is flowing through the circuit.
When the ignition timing detecting circuit is activated, the signal transmitter transistor actuates with cur-
rent d flowing. When current @ starts flowing, current @ flowing through the power transistor is
cut quickly. As a result, high voltage is produced in the secondary coil and this voltage is applied simul-
taneously to the spark plug which ignites for ignition. This stage corresponds to the opening of contact
points.
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