Ignition System - Husqvarna K1270 Workshop Manual

Ignition system

9. IGNITION SYSTEM
9.1. FUNCTION
The ignition system is fully enclosed and has no
moving parts. It is insensitive to moisture and dirt.
The design is such that the ignition point does not
need to readjustment.
Husqvarna K1270 has integrated overspeed
protection in the electronic unit that limits the
engine's speed to 9,300 rpm.
The ignition system consists of the primary coil (A)
and secondary coil (B) which are both surround ed
by the iron core (C). An electronic digital unit (D)
manages the switch function.
Current is generated in the primary coil when the
flywheel's permanent magnet passes the coil and
has the voltage sequence illustrated in the diagram
to the right. (The dashed line indicates the voltage
that should be generated if the current is not
broken.)
The ignition point is determined by the electronic
unit, which sense the voltage variation in the
primary coil and breaks the current at the right
level, at the same time the engine piston is just
below the upper turning point. At the breaking
instant the voltage in the primary coil rises from 5
V (volt) to approximately 200 V through induction.
At the same time a high voltage, approximately
20,000 volt, is transformed in the secondary coil to
the spark plug.
9.2. IGNITION MODULE
The ignition module components are fully enclosed
to withstand external effects. Individual compo-
nents cannot be replaced.
The ignition cable, the contact unit to the spark
plug and the seal on the ignition module can be
replaced.
The ignition module requires no routine service
measures. (However, the distance to the flywheel
magnet can be adjusted where necessary.)
Besides the connection to the spark plug there are
two connections on the ignition module. The arrow-
marked flat pin connector connects to the stop
switch. The other is the power outlet for machines
with OilGuard.
9.3. SPARK PLUG
The spark plug's electrode gap should be .02
in./0.5 mm.
The electrodes should be free of soot deposits and
oil. Brush clean with a wire brush.
A convex centre electrode and a worn side elec-
trode impair the ignition characteristics.
Replace the spark plug.
30
- English
A
C B
2 1
3
FUNCTION
IGNITION MODULE
.02 in.
0.5 mm
SPARK PLUG
2
+
Volts
Ignition
point
0
3
-
1
Electronic
circuit
D
breaker
STOP
control