Wacker Neuson WM 90 User Manual

Sub Systems WM 90 Repair
wc_tx000390gb.fm 72
9. Sub Systems
9.1 Magneto
The ignition system of the WM 90 is a breakerless flywheel magneto
with an automatic advancing system.
This system has no breaker points and thus is free from the starting
and running problems associated with dirty, burnt, or corroded breaker
points.
The electronic automatic advancing ensures easy starts and high
performance at operating speed by advancing the ignition timing to the
most suitable point.
9.2 Engine Basic Electric Theory
See Graphic: wc_gr001916
9.2.1 Revolution of the flywheel generates electricity in the primary side of
the ignition coil, and the base current I
1
flows to the power transistor.
Current I
1
turns the power transmitter “ON” and the electric current I
2
flows.
9.2.2 At lower engine revolution, when the flywheel reaches the ignition
point, the low speed ignition timing control circuit operates to run the
base current I
3
to turn the signal transistor A “ON” allowing the current
I
1
to bypass as current I
4
.
At this moment, the power transistor turns “OFF” and the current I
2
is
abruptly shut off resulting in the high voltage generated in the
secondary coil which produces sparks at the spark plug.
9.2.3 At higher engine revolution, the advancing control circuit operates at
the ignition timing to run the base current I
5
to turn the signal transistor
B “ON” allowing the current I
1
to bypass as current I
6
.
At this moment the power transistor turns “OFF” and the current I
2
is
abruptly shut off resulting in the high voltage generated in the
secondary coil which produces sparks at the spark plug.
The operating timing of the advancing control circuit advances in
accordance with the increase of engine speed resulting in the
advancing of the ignition timing shown in the chart.

Wacker Neuson WM 90 Specifications

General

Brand	Wacker Neuson
Model	WM 90
Category	Engine
Language	English