Spark Plug - Stihl BR 450 C-EF Instruction Manual

Erratic idling behavior, engine stops
even though setting of LA screw has
been corrected, poor acceleration
Idle setting is too lean
Turn the low speed screw (L)
N
counterclockwise, no further than
stop, until the engine runs and
accelerates smoothly.
Erratic idling behavior
Idle setting is too rich
Turn the low speed screw (L)
N
clockwise, no further than stop, until
the engine runs and accelerates
smoothly.
It is usually necessary to change the
setting of the idle speed screw (LA) after
every correction to the low speed
screw (L).
Fine Tuning for Operation at High
Altitude
A slight correction of the setting may be
necessary if the engine does not run
satisfactorily:
Carry out the standard setting.
N
Warm up the engine.
N
Turn high speed screw (H) slightly
N
clockwise (leaner) – no further than
stop.
NOTICE
After returning from high altitude, reset
the carburetor to the standard setting.
If the setting is too lean there is a risk of
engine damage due to insufficient
lubrication and overheating.
BR 450, BR 450 C

Spark Plug

If there is a loss of engine power, the
machine is difficult to start or runs poorly
at idle, first check the spark plug.
Install a new spark plug after approx.
100 operating hours or earlier if the
electrodes are eroded/corroded.
The wrong fuel mix (too much engine oil
in the gasoline), a dirty air filter and
unfavorable running conditions (mostly
at part throttle etc.) affect the condition
of the spark plug. These factors cause
deposits to form on the insulator nose,
which may degrade performance.
Removing the spark plug
2
Pull off the spark plug boot (1)
N
vertically.
Unscrew the spark plug (2).
N
Checking the Spark Plug
Clean dirty spark plug.
N
Check electrode gap (A) and
N
readjust if necessary – see chapter
"Specifications."
Use only resistor type spark plugs of
N
the approved range.
Rectify problems which have caused
fouling of spark plug:
too much oil in fuel mix,
–
dirty air filter,
–
unfavorable running conditions, e.g.
–
operating at part load.
English
A
21