Stihl FC 90 - Replacing the Starter Rope and Rewind Spring

26 Series 4180 Powerhead
– Adjust engine idle speed with the
aid of a tachometer,
b
3.1;
note that there is an ignition
spark on every revolution of
the crankshaft.
– Check idling behavior by opening
the throttle several times. Make
sure engine idles and
accelerates smoothly.
If the engine stops while idling:
– Turn the idle speed screw
clockwise until the attachment
begins to run. Then turn the
screw back one quarter of a turn
from that position
If the attachment runs while the
engine is idling:
– Turn idle speed screw
counterclockwise until the
attachment stops running. Then
turn the screw about another
quarter turn in the same direction.
A slight correction of the setting of
the high speed screw (H) may be
necessary (no further than stop) if
engine power is not satisfactory
when operating at high altitude, sea
level or after changing the
attachment.
– Turn the high speed screw H
clockwise (leaner) at high altitude
or counterclockwise (richer) at
sea level.
The limiter caps only need to be
removed from the screws if it is
necessary to replace the high speed
screw (H) or low speed screw (L),
clean the carburetor or carry out the
basic setting, b
6.4.1.
Remove the limiter caps to carry out
the basic setting:
: Push the puller
5910 890 4501 (1), with the
groove facing the limiter cap,
between the limiter cap (2) and
carburetor body.
VA
249RA161
21
: Pry off the cap (2). If the limiter
cap is stuck on the adjusting
screw, turn the puller over so that
its groove faces the carburetor
body. Pry off the limiter cap.
The basic setting must be carried
out after removing the limiter caps.
Do not re-install used caps because
they may have been damaged
during the removal process.
: Carefully screw the high speed
screw H (1) and low speed
screw L (2) clockwise down onto
their seats.
VA
249RA165
2
1
The basic setting is carried out with
the high speed screw H and the low
speed screw L as follows:
FS 90; FC 90, 95; KM 90
(C1Q-S110)
– Open the high speed screw H
3 1/2 turns counterclockwise.
– Open the low speed screw L
1 1/4 turns counterclockwise.
FS/FC/KM 100, 110; HT 100, 101
(C1Q-S72, C1Q-S81, C1Q-S88)
– Open the high speed screw H
2 turns counterclockwise.
– Open the low speed screw L
3 turns counterclockwise.
FS/KM 130; HT 130, 131
(C1Q-S98)
– Open the high speed screw H
4 turns counterclockwise.
– Open the low speed screw L
2 3/8 turns counterclockwise.
FS/KM 130; HT 131
(C1Q-S114) Brazil only
– Open the high speed screw H
2 1/2 turns counterclockwise.
– Open the low speed screw L
2 5/8 turns counterclockwise.
6.4.1 Basic Setting