Technical Tips; Tci System - Yamaha F2.5A Service Manual

Technical tips

TCI system

The TCI system operates as follows.
Before ignition
As the flywheel rotates, the primary coil generates a voltage and an electric current A. This electric
current opens transistor Q1 and, as a result, an electric current B flows to the primary coil.
A
Ignition
As the flywheel continues to rotate, the voltage generated by the primary coil increases.
When the voltage reaches the operation voltage of transistor Q2, an electric current C flows to tran-
sistor Q2 and opens it. As a result, electric current D flows.
Ignition timing occurs in this instant.
At ignition timing, the electric current B flowing to the primary coil through transistor Q1 is cut off,
the secondary coil generates a high voltage by electric induction and an ignition spark is fired by the
spark plug.
C
69M3E11
B
Q
1
Q
2
B
Q
1
D
Q
2
Features and benefits / Technical tips
1
1
2
3
4
S69M1200
5
6
7
8
9
S69M1210
1-12