STIHL 064, 066 46
5.1 Repairing Component
Parts
5.1.1 Spark Plug
Troubleshooting on the ignition Sooted or carbonized spark plug:
system should always begin at
the spark plug. - Use brass wire brush to clean the
spark plug and then blow it clear
In the event of starting difficulties, with compressed air.
low engine power, misfiring, etc.,
unscrew the spark plug and check Note: Never use a steel wire
that it is the approved type. Only brush for this job.
the spark plugs listed in the spe-
cifications may be used. Other
makes of spark plug are unsuit- Spark plug smeared with oil:
able because they have long-
reach electrodes. - Wash the insulator nose with a
grease solvent and blow it clear
Unlike analog ignition systems, the with compressed air.
spark plug is a functional compo
nent of ignition timing in machines
with digital ignition. The internal Electrode gap:
circuity is designed for suppressed
spark plugs. For this reason only Electrode gap becomes wider as
install one of the spark plugs listed a result of normal erosion.
in the specifications. The following
faults may occur if other spark
plugs are used:
- Misfiring at idle speed
- Misfiring when warm machine is
running at cutting speed
- Misfiring during acceleration
- Detonations in the crankcase at
idle speed and full load.
- Check the gap at regular intervals with a
feeler gauge. It should be 0.5 mm (0.02").
- Bend the ground electrode as
necessary.
Important: Always fit a new spark plug if the
electrodes are badly pitted.
Top:
Checking electrode gap with feeler
gauge
Bottom:
Resetting electrode gap with
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