Ignition Timing Control - Yamaha FT50C Service Manual

GEN
INFO

Ignition timing control

Control circuit diagram
Operation
Engine start
Acceleration
Over-revolution
Low oil pressure
Overheat
Basic control
The ignition timing is determined by using the map based on the engine speed (r/min). Then, igni-
tion signals are output from the microcomputer in accordance with the ignition timing map so that
ignition can take place at the optimal timing in relation to the engine speed. Then, the microcom-
puter corrects the ignition timing in accordance with the operating conditions of the engine as
detected by the signals that are input from the engine temperature sensor and oil pressure sensor.
The pulser signals that are output when the protrusions for cylinders #1 and #4, and for cylinders #2
and #3 pass by the pulser coil, are used to calculate the engine speed. In addition, the pulser sig-
nals are used to determine the forecast starting position of the ignition timing.
9
1 Cylinder identification protrusion
2 Pulser coil
3 Protrusion for cylinders #1 and #4
4 Protrusion for cylinders #2 and #3
5 Pulser coil signal
1-17
General information
Detection
Engine temperature
Engine speed
Oil pressure
2
3
1
5
7
6
Microcomputer
Ignition timing control
(optimized ignition
timing)
Engine speed control
Warning buzzer
(in remote-control
unit)
Warning lamp
(low oil pressure)
Warning lamp
(to overheat)
4
8
6 Cylinder identification signal
7 Identification signal for cylinders #1 and #4
8 Identification signal for cylinders #2 and #3
9 Rotating direction
Positive start
Quick acceleration
Damage prevention
S62Y1330
S62Y1340
62Y5A11