WM, Workshop Manual, K650, K700, K950, K1250, 2001-06, Power ...

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Ignition system
The engine is fitted with an electronic ignition system
consisting of flywheel, ignition coil and trigger
unit.
The ignition system has no moving parts. A defective
component cannot be repaired but must be replaced
with a new one.
The ignition spark in an electronic ignition system
has a very short burn time and may therefore be
experienced as weak, and sometimes be dif ficult to
see during trouble shooting.
NOTE!
During all test running of the cutting saw the
clutch and clutch cover must be fitted before the
engine is started!
C
N
3
B
B
2
S
N
A
1
S
+
0
-
Volts
1
D
2
G
E
3
F
E = Ignition point
F = Trigger unit
G = Stop switch
Principle of the ignition
system
The ignition system is completely enclosed
and no after-adjustment of the
ignition point is possible or necessary.
The ignition module is built up of an iron
core (C). Round this lies the primary coil
(A) which consists of a small number of
turns of thick copper wire. Outside this
lies the secondary coil (B) which has a
very large number of turns of copper
wire.
The trigger unit (F) is fitted on the
secondary coil and has the purpose of
breaking the current (D) in the primary
winding at exactly the right time, i.e. just
before the piston reaches the top dead
centre.
When the permanent magnet (1) on the
flywheel passes the ignition module’s
iron core, an electric current is generated
in the primary coil (A). At the breaking
moment the current in the primary coil
rises from 5 volts to approx. 200 volts by
means of induction.
In the secondary coil (B) a high voltage
(approx. 20 000 volts) is simultaneously
transformed to the spark plug.
Models K650,K700, K950 and K1250
have a built-in overspeeding protection
in the electronic unit which limits the
unloaded speed of the engine to about
9 750 rpm.
C
A
The ignition module components are
completely enclosed to protect them from
moisture and dirt.
In the event of a failure in the ignition
module it must be replaced with a new
one.
The ignition module components are
completely enclosed to protect them from
moisture and dirt.
In the event of a failure in the ignition
module it must be replaced with a new
one.
F
A = Primary coil
B = Secondary coil
C = Iron core
F = Trigger unit
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