Ignition System; Ignition Timing On All Models; Ignition Module / Control Unit; Removing And - Stihl MS 661 Manual

7.

Ignition System

Exercise extreme caution when
troubleshooting and carrying out
maintenance or repair work on the
ignition system. The high voltages
which occur can cause serious or
fatal accidents.
Do not turn the engine over with the
rewind starter when the spark plug
boot or the spark plug is removed
– there is otherwise a risk of fire due
to sparking outside the cylinder.
Troubleshooting on the ignition
system should always begin at the
spark plug, b 3.5
– Remove the rewind starter,
b 9.2
Models without M-Tronic
2 1
The electronic (breakerless) ignition
system basically consists of an
ignition module (1) and flywheel (2).
Models with M-Tronic
For operation and description see
chapter on M-Tronic, b 8.
MS 661, MS 661 C-M
7.1 Ignition Timing
on All Models
Ignition timing is fixed and cannot
be adjusted during repair work.
Since there is no mechanical wear
in these systems, ignition timing
cannot get out of adjustment during
operation.
7.2 Ignition Module /
Control Unit
Ignition module
The ignition module accommodates
all the components required to
control ignition timing. There are
two electrical connections on the
coil body:
– the high voltage output (1) for the
ignition lead
– the connector tag (2) for the short
circuit wire
Testing in the workshop is limited to
a spark test. A new ignition module
must be installed if no ignition spark
is obtained (after checking that
wiring and stop switch are in good
condition).
Control Unit
The control unit accommodates all
the components required to control
ignition timing and fuel feed. There
are three electrical connections on
the control unit:
1
– the high voltage output (1) for the
ignition lead
2
– Connector tag (2) for the black
wire – short circuit wire
– Connector tag (3) for the read
wire
– M-Tronic
Testing the control unit is not limited
to the spark test alone. If the ignition
spark or another function fails, the
system must be checked with the
aid of the troubleshooting chart and
the control unit of M-Tronic wiring
harness replaced if necessary,
b 8.7
7.3 Removing and Installing
– Remove the rewind starter,
b 9.2
– Remove the filter cover and pull
off the spark plug boot.
1
3
2
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