MS 193 C
English
33
N
Turn the low speed screw (L)
counterclockwise, 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 engine does not run
satisfactorily:
N
Carry out the standard setting.
N
Warm up the engine.
N
Turn high speed screw (H) slightly
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.
N
If the engine is down on power,
check the spark arresting screen in
the muffler.
N
Wait for the muffler to cool down.
N
Remove the sprocket cover.
N
Take out the screw (1).
N
Remove the baffle plate (2).
N
Remove the spark arresting
screen (3).
N
Clean the spark arresting screen. If
the screen is damaged or heavily
carbonized, fit a new one.
N
Refit the spark arresting screen.
N
Fit the baffle plate.
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
Insert a suitable tool in the side of
the spark plug boot.
N
Pry off the spark plug boot.
N
Unscrew the spark plug.
Spark Arresting Screen in
Muffler
3
1
467BA020 KN
2
Spark Plug
418BA009 KN
