Stihl FS 120 User Manual

39FS 120, FS 120 R, FS 200, FS 200 R, FS 250, FS 250 R
English / USA
Standard Setting
: Shut off the engine.
: Mount the cutting tool.
: Check the air filter and replace if
necessary.
: Check that throttle cable is properly
adjusted – readjust if necessary –
see chapter "Adjusting the Throttle
Cable".
: Turn high speed screw (H)
counterclockwise (max.
3
/
4
turn) as
far as stop.
: Carefully screw the low speed
screw (L) down onto its seat. Then
open it one turn counterclockwise.
: Start the engine and run it until it is
warm.
: Adjust idle speed with the idle speed
screw (LA) so that the cutting tool
does not rotate.
Fine Tuning
A slight correction of the setting of the
high speed screw (H) may be necessary
if engine power is not satisfactory after a
change in altitude (mountains, sea level)
or after changing the cutting tool.
Rule of Thumb
Rotate the high speed screw (H)
about one eighth of a turn for every
3300 ft (1000 meter) change in
altitude.
Conditions for Adjustment
Adjust the high speed screw (H)
only if you are using a mowing head,
making sure the cutting lines are full
length (as far as the limiter blade on
the deflector).
If you mount a metal cutting tool,
use the standard setting.
: Carry out the standard setting.
Maximum engine speed is normally
reached with the standard setting.
: Warm up engine for about 5 minutes
if you are using a metal cutting tool
or about 3 minutes if you are using a
mowing head.
: Open the throttle wide – and:
At high altitude
: Turn high speed screw (H) clock-
wise (leaner) no further than stop
until there is no noticeable increase
in engine speed.
At sea level
: Turn the high speed screw (H)
counterclockwise (richer) no further
than stop until there is no noticeable
increase in engine speed
Idle Speed
It is usually necessary to change the
setting of the idle speed screw (LA)
after every correction to the low speed
screw (L).
: Warm up the engine.
Engine stops while idling
: Turn idle speed screw (LA) slowly
clockwise until the engine runs
smoothly – the cutting tool must not
rotate.

Stihl FS 120 Specifications

General

Power source	Gasoline
Type	Brush cutter
Cordless	Yes
Head type	Nylon line
Handle type	U-type handle
Engine power	1.8 hp
Product color	Black, Metallic, Orange
Uncertainty K	2 m/s²
Sound power level	110 dB
Fuel tank capacity	0.64 L
Vibration emission	4.9 m/s²
Engine displacement	30.8 cm³
Sound pressure level	98 dB
Cutting diameter (max)	- mm

Weight and Dimensions

Length	1760 mm
Weight	6300 g