Kawasaki FE120 Automobile Parts User Manual


 
DISASSEMBLY, REASSEMBLY, INSPECTION, AND MAINTENANCE 3-13
Ignition System
Description of Function
The ignition mechanism is the transistorized type and consists of the
following parts:
Ignition Coil
Igniter
Flywheel (with permanent magnet)
These components do not contain mechanical contact parts and do
not require regular inspection.
Electronic Ignition Device
The revolution of the flywheel generates voltage between terminals
[A] and [B], causing base current IB1 to flow from TR1. Then, current
IC1 that is amplified by TR1 flows to form the primary circuit.
The flywheel revolves further and the voltage that is generated
between terminals [A] and [B] increases. When the flywheel reaches
the position of the ignition timing, signal base current IB2 flows from
automatic ignition advance circuit C to transistor TR2. At that instant,
the current changes into collector current IC2, which is amplified by
transistor TR2.
In the meantime, because the internal resistance of TR2 is consider-
ably lower than TR1, IB1 that was flowing through TR1 until then will
turn into IC2, thus changing its direction to flow via TR2.
In this manner, base current IB1 of TR1 will not momentarily flow,
thus causing large current IC1 that was flowing between terminals
[A] and [B] until then to stop suddenly.
Due to the sudden change in the current in the primary circuit, a high
voltage is generated in secondary side [F], causing spark plug [G] to
spark.
A, B: Igniter Terminal
C: Automatic Ignition Advance Circuit
E: Primary Coil
F: Secondary Coil
G: Spark Plug
ESW: Engine Switch