Stihl Fs 90 R Manual

FS 90, FS 90 R
English
29
Opening the filler cap
NTurn the cap counterclockwise until 
it can be removed from the tank 
opening.
NRemove the filler cap.
Refueling
Take care not to spill fuel while fueling 
and do not overfill the tank.
Closing the filler cap
NPosition cap.
NTurn the cap clockwise as far as it 
will go and tighten it as securely as 
possible by hand.The type and style of the 
harness/shoulder strap depend on the 
market.
The use of the shoulder strap is 
described in the chapter on...

FS 90, FS 90 R
English
30
Attaching the unit to the harness
The type and style of the harness and 
carabiner (spring hook) depend on the 
market.
NAttach the carabiner (1) to the 
carrying ring (2) on the drive tube.NLoosen the screw (3).
Balancing the brushcutter
The unit is balanced differently, 
depending on the cutting attachment 
used.
Proceed as follows until the conditions 
specified under "Floating positions" 
have been met:
NAdjust the carrying ring.
NTighten the screw moderately.
NAllow...

FS 90, FS 90 R
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31
Detaching the unit from the harness
NPress down the bar on the 
carabiner (1) and pull the carrying 
ring (2) out of the carabiner.
Operating elements
Control handle on handlebar
1Throttle lever lock
2Throttle trigger
3Slide controlControl handle on shaft
1Throttle lever lock
2Throttle trigger
3Slide control
Slide control positions
4STOP-0 – engine off – ignition is 
switched off
5Operating position F – Run – engine 
is running or can start
6START – Start – the ignition is...

FS 90, FS 90 R
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32
Starting
NPress the throttle trigger lockout and 
throttle trigger in succession
NHold both triggers down
NMove the slide control to START 
and hold it in position too
NRelease the throttle trigger, slide 
control and throttle trigger lockout in 
succession = starting throttle 
position
NSet the choke knob (8)
NPress the manual fuel pump 
bulb (9) at least 5 times - even when 
bulb is filled with fuelStarting
NLay the machine on the ground in a 
secure position: It must rest on...

FS 90, FS 90 R
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33
Switching off the engine
NPush the slide control in the 
direction of the arrow at the stop 
signh to STOP-0
At very low temperatures
As soon as engine is running:
NBlip the throttle trigger = disengage 
starting throttle position – the slide 
control jumps to runF – engine 
begins to idle
NPress the throttle trigger slightly
NLet the engine warm up briefly
If the engine does not start
Choke knob
If the choke knob was not returned to e 
in time after the engine turned over for...

FS 90, FS 90 R
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34
250 mm Brush Knives
Circular Saw Blades
NDisconnect wire rod from the 
transport guard.
681BA270 KN
681BA272 KN
681BA268 KN
681BA269 KN
681BA271 KN
681BA272 KN
681BA302 KN
681BA275 KN1.
2. 

FS 90, FS 90 R
English
35 NSwing wire rod outwards.
NFit transport guard on saw blade 
from below, making sure the limit 
stop is properly seated in the 
recess.
NSwing wire rod into position.
NHook wire rod to the transport 
guard.
During break-in period
A factory-new machine should not be 
run at high revs (full throttle off load) for 
the first three tank fillings. This avoids 
unnecessary high loads during the 
break-in period. As all moving parts 
have to bed in during the break-in 
period, the...

FS 90, FS 90 R
English
36 Exhaust emissions are controlled by the 
design of the fundamental engine 
parameters and components (e.g. 
carburation, ignition, timing and valve or 
port timing) without the addition of any 
major hardware.The carburetor of the machine has been 
adjusted for optimum performance and 
fuel efficiency in all operating states at 
the factory.
Setting the idle speed
Engine stops when idling
NLet the engine warm up for approx. 
3min
NSlowly turn idle speed screw (LA) 
clockwise...

FS 90, FS 90 R
English
37 NTake out the screw (4).
NLift the spark arresting screen (5) 
and pull it out.
NClean the spark arresting screen. If 
the screen is damaged or heavily 
carbonized, fit a new one.
NRefit the spark arresting screen.
NInsert screw and tighten it down 
firmly.
NInstall the shroud.If engine is down on power, difficult to 
start or runs poorly at idling speed, first 
check the spark plug.
Fit a new spark plug after approx. 100 
operating hours or earlier if the 
electrodes are badly...

FS 90, FS 90 R
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38
WARNING
To reduce the risk of fire and burn injury, 
use only spark plugs authorized by 
STIHL. Always press spark plug boot (1) 
snugly onto spark plug terminal (2) of the 
proper size. (Note: If terminal has 
detachable SAE adapter nut, it must be 
securely attached.) A loose connection 
between spark plug boot and ignition 
wire connector in the boot may create 
arcing that could ignite combustible 
fumes and cause a fire.
Installing the spark plug
NScrew home the spark plug,...