Ignition System - Yamaha F50D Servise Manual

Ignition system

In order to determine the optimal ignition timing that is necessary for the proper operation of the
engine, the built-in microcomputer in the CDI unit detects the signals from various types of sensors
and controls the ignition timing in accordance with a control map that is based on those signals. The
microcomputer also effects controls to protect the engine against overheating, over revolution, and
oil pressure drops, as well as to control alert devices.
2
1
1 Pulser coil
2 Flywheel magnet
3 Charge coil
4 CDI unit
5 Microcomputer
Flywheel magnet
Three protrusions for the pulser coil are provided along the ambience of the flywheel magnet. The
purpose of these protrusions is for detecting the engine speed. Two of them are used for ignition sig-
nals, and one is used for identifying the cylinders, and these signals are transmitted to the
microcomputer.
4
3
5
8
9
6 Ignition coil #1 and #4
7 Ignition coil #2 and #3
8 Oil pressure switch
9 Thermoswitch
Electronic control system
6
7
0
1
2
3
4
5
6
7
8
9
10
A
2-2