Stihl BT 120 C - Spark Plug Inspection and Cleaning

21BT 120 C
English / USA
Adjusting Idle Speed
Engine stops while idling
: Standardeinstellung an der
Leerlaufstellschraube (L)
vornehmen
: Turn the idle speed screw (LA)
clockwise until the engine runs
smoothly – the drilling spindle must
not rotate.
Drilling spindle rotates when engine
is idling
: Turn the idle speed screw (LA)
counterclockwise until the drilling
spindle stops rotating – then turn the
screw about another half to one full
turn in the same direction from that
position.
Erratic idling behavior, poor
acceleration
: Carry out standard setting with the
low speed screw (L).
Idle setting too lean:
: Turn the low speed screw (L)
counterclockwise 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 the carburetor for
operation at high altitude
A slight correction may be necessary if
the engine does not run satisfactorily:
: Check the standard setting.
: Warm up the engine.
: Turn the high speed screw (H)
clockwise (leaner).
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.
Checking the Spark Plug
000BA002 KN