Stihl FS 80 Instruction Manual page 41

English / USA
Rule of thumb
Turn high speed screw (H) about
1/4 turn over for every 1000m
(3.300 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 limiter blade on
the deflector).
If you mount a metal cutting tool,
use the standard setting.
: Carry out standard setting without
changing position of high speed
screw (H).
: 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.
40
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 high speed screw (H) counter-
clockwise (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.
Adjusting 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.
Cutting tool rotates when engine is
idling
: Turn idle speed screw (LA) slowly
counterclockwise until cutting tool
stops rotating and then turn the
1
screw about another /
the same direction.
Erratic idling behavior, engine stops
even though setting of LA screw is
correct, poor acceleration
Idle setting too lean:
: Turn low speed screw (L)
counterclockwise (about
until the engine runs and
accelerates smoothly.
Erratic idling behavior
Idle setting too rich:
: Turn low speed screw (L) clockwise
1
(about / turn) until the engine runs
4
and accelerates smoothly.
FS 80, FS 80 R, FS 85, FS 85 R
to 1 turn in
2
1
/ turn)
4