Instruction Manual

MS 271, MS 271 C, MS 291, MS 291 C
English
37
N If the engine is down on power,
difficult to start or runs poorly at idle
speed, first check the spark plug.
N Fit a new spark plug after about 100
operating hours – or sooner if the
electrodes are badly eroded. Install
only suppressed spark plugs of the
type approved by STIHL – see
"Specifications".
Removing the spark plug
N Remove the shroud – see "Shroud".
N Move the Master Control lever to the
stop position (0).
N Pull off the spark plug boot.
N Clean away loose dirt from around
the spark plug.
N Insert the combination wrench
through the grommet (1) and turn it
as necessary to engage the spark
plug's hexagon.
N Push the combination fully home
against the cylinder.
N Unscrew the spark plug.
Checking the Spark Plug
N Clean dirty spark plug.
N Check electrode gap (A) and
readjust if necessary – see
"Specifications".
N Rectify the problems which have
caused fouling of the spark plug.
Possible causes are:
Too much oil in fuel mix.
Dirty air filter.
Unfavorable running conditions.
WARNING
Arcing may occur if the adapter nut (1) is
loose or missing. Working in an easily
combustible or explosive atmosphere
may cause a fire or an explosion. This
can result result in serious injuries or
damage to property.
N Use resistor type spark plugs with a
properly tightened adapter nut.
Installing the spark plug
N Insert the spark plug through the
grommet and screw it in by hand.
N Tighten down the spark plug, fit the
boot and press it down firmly.
N Install the shroud – see "Shroud".
Spark Plug
5902BA013 KN
000BA039 KN
A
1
000BA045 KN
5902BA016 KN