Stihl FS 85 Instruction Manual page 86

English
H
3 / 4
Turn high speed screw (H)
N
counterclockwise as far as stop (no
more than 3/4 turn).
Turn the low speed screw (L)
N
carefully clockwise as far as stop,
then turn it back 1 turn
Start and warm up the engine.
N
Adjust idle speed with the idle speed
N
screw (LA) so that the cutting
attachment does not run.
Fine Tuning
A slight correction of the setting of the
high speed screw (H) may be necessary
if engine power is not satisfactory when
operating at high altitude, sea level or
after changing the cutting attachment.
84
Rule of thumb:
Turn the high speed screw (H) about
one quarter turn for every 1000 m (3300
ft) change in altitude.
L
1 Conditions for adjustment
WARNING
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 line limiter blade on the
deflector).
LA
If a metal cutting attachment is mounted,
use the standard setting and adjust the
high speed screw (H) as described
above under "Rule of thumb".
Carry out the standard setting.
N
Start the engine and, with the
N
mowing head mounted, warm it up
for about 3 minutes.
Open the throttle wide.
N
At high altitude
Turn the high speed screw (H)
N
clockwise (leaner), no further than
stop, until there is no noticeable
increase in engine speed.
At sea level
Turn the high speed screw (H)
N
counterclockwise (richer), no further
than stop, until there is no
noticeable increase in engine
speed.
It is possible that maximum engine
speed may be reached with the standard
setting in each case.
Adjust 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.
N
Engine stops while idling
Turn the idle speed screw (LA)
N
slowly clockwise until the engine
runs smoothly – the cutting
attachment must not run.
Cutting attachment runs when engine is
idling
Turn the idle speed screw (LA)
N
counterclockwise until the cutting
attachment stops moving and then
rotate the screw another 1/2 to 1
turn in the same direction.
WARNING
If the cutting attachment continues to run
when the engine is idling, have your
machine checked and repaired by your
servicing dealer.
Erratic idling behavior, engine stops
even though setting of LA screw has
been corrected, poor acceleration
Idle setting is too lean
Idle setting is too lean: Rotate the
N
low speed screw (L) about 1/4 turn
counterclockwise until the engine
runs and accelerates smoothly.
Erratic idling behavior
Idle setting is too rich:
FS 85, FS 85 R