30
English / USA
FS 90, FS 90 R
STIHL FixCut 25-2
: Place the mowing head on the 
thrust plate (2).
Collar (arrows) must locate in the 
mowing head’s mounting hole
: Push the thrust washer (3) over the 
shaft (1) so that it locates against 
the base.
: Block the output shaft.
: Screw the mounting nut (4) with the 
combination wrench (5) 
counterclockwise on to the output 
shaft and tighten down firmly.
Remove the tool used to block the 
shaft.
Removing the Mowing Head
: Block the output shaft.
STIHL SuperCut 20-2, 
STIHL AutoCut 25-2, 
STIHL AutoCut C 25-2, 
STIHL TrimCut 30-2, 
STIHL PolyCut 20-3
: Unscrew the mowing head 
clockwise.
STIHL FixCut 25-2
: Use the combination wrench to 
unscrew the mounting nut clockwise 
from the output shaft
If the mounting nut is too loose, fit a 
new one
Adjusting Nylon Line
STIHL SuperCut
Fresh line is advanced automatically if 
remaining line is still min. 2 1/2" (6 cm) 
long. The blade on the deflector trims 
overlong line to the correct length.
STIHL AutoCut
: Hold the rotating mowing head 
above the ground – tap it on the 
ground once – about 1 1/4" (3 cm) 
fresh line is advanced. 
The blade on the deflector trims 
overlong line to the correct length – 
avoid tapping head more than once at a 
time.
Line feed operates only if both lines 
still have a minimum length of 1" 
(2.5 cm).
All other mowing heads
Refer to the instructions supplied with 
the mowing head.
To reduce the risk of injury, always 
shut off the engine before adjusting 
the nylon line by hand.
Replacing Nylon Line or Cutting 
Blades
Refer to the instructions supplied with 
the mowing head.