Spark Plug; Engine Running Behavior; Storing The Machine - Stihl BR 450 Instruction Manual

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NOTICE
After returning from high altitude, reset the car‐
buretor to the standard setting.
If the setting is too lean there is a risk of engine
damage due to insufficient lubrication and over‐
heating.

13 Spark Plug

► If the engine is down on power, difficult to start
or runs poorly at idle speed, first check the
spark plug.
► 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 "Specifica‐
tions".
13.1 Removing the spark plug
► Pull off the spark plug boot (1) vertically.
► Unscrew the spark plug (2).
13.2 Checking the Spark Plug
► Clean dirty spark plug.
► Check electrode gap (A) and readjust if neces‐
sary – see "Specifications".
► Rectify the problems which have caused foul‐
ing of the spark plug.
Possible causes are:
– Too much oil in fuel mix.
– Dirty air filter.
16
2
A
– 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 inju‐
ries or damage to property.
► Use resistor type spark plugs with a properly
tightened adapter nut.
13.3 Installing the spark plug
► Screw home the spark plug, fit the boot and
press it down firmly.

14 Engine Running Behavior

If engine running behavior is unsatisfactory even
though the air filter is clean and the carburetor is
properly adjusted, the cause may be the muffler.
Have the muffler checked for contamination (car‐
bonization) by your servicing dealer.
STIHL recommends that you have servicing and
repair work carried out exclusively by an author‐
ized STIHL servicing dealer.

15 Storing the Machine

If out of use for periods of about 30 days or lon‐
ger
► Drain and clean the fuel tank in a well ventila‐
ted area.
► Dispose of fuel properly in accordance with
local environmental requirements.
► If a manual fuel pump is fitted: Press the man‐
ual fuel pump at least 5 times.
► Start the engine and run it at idling speed until
it stops
► Thoroughly clean the machine, especially the
cylinder fins and air filter.
► Store the machine in a dry and safe location.
Keep out of the reach of children and other
unauthorized persons
13 Spark Plug
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0458-391-8321-B