Stihl FS 55R Instruction Manual page 29

Rule of thumb:
Turn the high speed screw (H) about
one quarter of a turn for every 1000 m
(3300 ft) 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
line limiter blade on the deflector).
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".
N Carry out the standard setting.
N Start the engine and, with the
mowing head mounted, warm it up
for about 3 minutes.
N Open the throttle wide.
At high altitude
N Turn the high speed screw (H)
clockwise (leaner), no further than
stop, until there is no further
noticeable increase in engine
speed.
At sea level
N Turn the high speed screw (H)
counterclockwise (richer), no further
than stop, until there is no further
noticeable increase in engine
speed.
It is possible that maximum engine
speed may be reached with the standard
setting in each case.
FS 55, FS 55 C, FS 55 R, FS 55 RC
Aadjusting 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).
N Warm up the engine.
Engine stops while idling
N
Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly – the cutting
attachment must not turn.
Cutting attachment rotates when
engine is idling
N
Turn the idle speed screw (LA)
counterclockwise until the cutting
attachment stops moving and then
rotate the screw another 1/2 to 1
turn in the same direction.
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:
N
Idle setting is too lean: Rotate the
low speed screw (L) about 1/4 turn
counterclockwise until the engine
runs and accelerates smoothly.
Erratic idling behavior
Idle setting is too rich
N Rotate the low speed screw (L)
about 1/4 turn clockwise until the
engine runs and accelerates
smoothly.
English
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