STIHL 009, 010, 011 24
4.4 Function and Repai
of Components
4.4.1 Spark Plug
The high-tension pulse generated in
ignition system is fed to the spark
plug and discharge as a sparkover
between the center and ground
electrodes.
When the spark plug is in good
condition and the electrode gap is
correct, the spark ignites the fuel-air
mixture.
The appearance of the spark
plug'sinsulator nose gives valuable
information with regard to the effects
of various operating conditions:
Troubleshooting on the ignition
system should always begin at
the spark plug.
In the event of starting difficulties,
low engine power or misfiring etc.,
unscrew the spark plug and check
whether it is one of the types
approved by STIHL.The Champion
RCJ 6Y suppressed spark plug is an
approved
alternative to the standard Bosch the
WSR 6 F (formerly WKA 200 TR 6).
These spark plugs cover a wide
thermal range and have better
operating characteristics under
severe conditions.
Appearance of insulator nose Some conditions associated
with appearance
Normal:
grey/yellow to brown, dry Engine in order; spark plug
heat range is correct
Sooted:
velvelt-like, dull black coating Mixture too rich, lack of air
of soot (dirty air filter, choke valve
partly closed), electrode gap
too wide, heat range too high
Smeared with oil:
coating of damp oil carbon Too much oil in fuel mix
and soot
Overheated:
welding beads on insulator Mixture too lean, spark plug
nose, eroded electrodes loose, heat range too low
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