Stihl BT 45 - Checking the Spark Plug

BT 45
English
22
Fine Tuning for Operation in Mountains
or at Sea Level
A slight correction of the setting of the
high speed screw (H) may be necessary
if engine power is not satisfactory when
operating at high altitude or at sea level.
N Check the standard setting.
N Warm up the engine.
N Adjust idle speed properly.
At high altitude
N Turn high speed screw (H)
clockwise (leaner) – no further than
stop.
At sea level
N Turn high speed screw (H)
counterclockwise (richer) – no
further than stop.
If the setting is too lean there is a risk of
engine damage due to insufficient
lubrication and overheating.
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 result in trouble in operation.
If engine is down on power, difficult to
start or runs poorly at idling speed, first
check the spark plug.
N Remove spark plug – see "Starting /
Stopping the Engine".
N Clean dirty spark plug.
N Check electrode gap (A) and
readjust if necessary – see
"Specifications".
N Use only resistor type spark plugs of
the approved range.
Rectify problems which have caused
fouling of spark plug:
N Too much oil in fuel mix.
N Dirty air filter.
N Unfavorable running conditions,
e.g. operating at part load.
Fit a new spark plug after approx. 100
operating hours or earlier if the
electrodes are badly eroded.
3/4
H
421BA028 KN
Checking the Spark Plug
000BA002 KN