STIHL FS 90 Owner's Manual
STIHL FS 90
Warning!
Read and follow all safety
precautions in Instruction Manual –
improper use can cause serious or
fatal injury.
Advertencia!
Lea y siga todas las precauciones
de seguridad dadas en el manual
de instrucciones – el uso incorrecto
puede causar lesiones graves o
mortales.
{
Instruction Manual
Manual de instrucciones
Instruction Manual
1 - 54
Manual de
instrucciones
55 - 113
Contents
English
Guide to Using this Manual 2
Safety Precautions and Working
Techniques 3
Approved Combinations of Cutting
Attachment, Deflector, Handle and
Harness 18
Approved Power Tool Attachments 20
Mounting the Bike Handle 20
Mounting the Loop Handle 22
Original Instruction ManualPrinted on chlorine-free paper
Adjusting the Throttle Cable 24
Fitting the Carrying Ring 24
Mounting the Deflector 24
Mounting the Cutting Attachment 25
4-MIX Engine 28
Fuel 29
Fueling 30
Fitting the Harness 31
Balancing the Trimmer/Brushcutter 32
Starting / Stopping the Engine 33
Operating Instructions 36
Cleaning the Air Filter 36
Engine Management 36
Printing inks contain vegetable oils, paper can be recycled.
Adjusting the Carburetor 37
Spark Arresting Screen in Muffler 38
Spark Plug 39
Lubricating the Gearbox 40
Replacing the Starter Rope and
Rewind Spring 40
Storing the Machine 42
Sharpening Metal Cutting Blades 43
Maintenance and Care 44
Main Parts 46
Specifications 48
Special Accessories 49
Maintenance and Repairs 49
STIHL Incorporated Federal
Emission Control Warranty
Statement 50
STIHL Incorporated California
Exhaust and Evaporative
Emissions Control Warranty
Statement 52
Trademarks 54
Allow only persons who fully understand
this manual to operate your trimmer /
brushcutter.
To receive maximum performance and
satisfaction from your STIHL trimmer /
brushcutter, it is important that you read,
understand and follow the safety
precautions and the operating and
maintenance instructions in chapter
"Safety Precautions and Working
Techniques" before using your trimmer /
brushcutter. For further information you
can go to www.stihlusa.com.
Contact your STIHL dealer or the STIHL
distributor for your area if you do not
understand any of the instructions in this
manual.
Warning!
Because a trimmer / brushcutter is a
high-speed cutting tool some special
safety precautions must be observed to
reduce the risk of personal injury. Careless or improper use may cause serious
or even fatal injury.
Make sure your unit is equipped with the
proper deflector, handle and harness for
the type of cutting attachment being
used. Always wear proper eye
protection.
{
© ANDREAS STIHL AG & Co. KG, 2011
0458-260-8621-C. M40.G11.CP.
0000000802_007_GB
FS 90, FS 90 R
1
English
Guide to Using this Manual
Pictograms
The meanings of the pictograms
attached to or embossed on the
machine are explained in this manual.
Depending on the model concerned, the
following pictograms may be on your
machine.
Fuel tank for gasoline
and engine oil mixture
Press to operate decompression valve
Manual fuel pump
Press to operate manual
fuel pump
Symbols in Text
Many operating and safety instructions
are supported by illustrations.
The individual steps or procedures
described in the manual may be marked
in different ways:
N A bullet marks a step or procedure.
A description of a step or procedure that
refers directly to an illustration may
contain item numbers that appear in the
illustration. Example:
N Loosen the screw (1).
N Lever (2) ...
In addition to the operating instructions,
this manual may contain paragraphs
that require your special attention. Such
paragraphs are marked with the
symbols and signal words described
below:
Danger!
Indicates an imminent risk of severe or
fatal injury.
Engineering Improvements
STIHL’s philosophy is to continually
improve all of its products. As a result,
engineering changes and improvements
are made from time to time. Therefore,
some changes, modifications and
improvements may not be covered in
this manual. If the operating
characteristics or the appearance of
your machine differs from those
described in this manual, please contact
your STIHL dealer for assistance.
Filler hole for gear
lubricant
Air intake summer mode
Air intake winter mode
Handle heating
2
Warning!
Indicates a hazardous situation which, if
not avoided, could result in severe or
fatal injury.
Caution!
Indicates a risk of property damage,
including damage to the machine or its
individual components.
FS 90, FS 90 R
English
Safety Precautions and
Working Techniques
Because a trimmer /
brushcutter is a highspeed, fast-cutting power
tool sometimes equipped
with sharp cutting blades,
special safety precautions must be observed to
reduce the risk of personal injury.
It is important that you
read, fully understand
and observe the following
safety precautions and
warnings. Read the
instruction manual and
the safety precautions
periodically. Careless or
improper use may cause
serious or fatal injury.
The terminology utilized in this manual
when referring to the power tool reflects
the fact that different types of cutting
attachments may be mounted on it. The
term "trimmer" is used to designate an
FS unit that is equipped with a nylon line
head or a head with flexible plastic
blades (i.e., the PolyCut head). A
"brushcutter" designates a unit
equipped with a rigid metal blade. Many
FS models may be used as either a
trimmer or a brushcutter – therefore, the
power tool is referred in this manual as a
"trimmer / brushcutter." Some smaller
and / or lightweight FS models may only
be used as a trimmer, i.e., they may not
be used with metal blades.
The term "clearing saw" indicates a
high-powered trimmer / brushcutter that
is particularly suited for use with a
circular saw blade to clear saplings or
small trees.
FS models with an "R" on the nameplate
were originally configured (at the time of
distribution) as a trimmer with a loop
handle.
Warning!
As more fully explained later in these
Safety Precautions, to reduce the risk of
personal injury, make sure your unit is
equipped with the proper handle, harness and deflector for the type of cutting
attachment you are using. Use only cutting attachments that are specifically
authorized by STIHL for use on your FS
model.
Have your STIHL dealer show you how
to operate your power tool. Observe all
applicable local safety regulations,
standards and ordinances.
Warning!
Do not lend or rent your power tool without the instruction manual. Be sure that
anyone using it understands the information contained in this manual.
Warning!
The use of this machine may be hazardous. If the rotating line or blade comes in
contact with your body, it will cut you.
When it comes in contact with solid foreign objects such as rocks or bits of
metal, it may fling them directly or by ricochet in the direction of bystanders or
the operator. Striking such objects could
damage the cutting attachment and may
cause blades to crack, chip or break.
Thrown objects, including broken heads
or blades, may result in serious or fatal
injury to the operator or bystanders.
STIHL does not recommend the use of
rigid blades when cutting in stony areas.
Use your trimmer / brushcutter equipped
with the appropriate cutting attachment
only for cutting grass, brush, wood and
similar material.
Warning!
Do not use it for other purposes, since
misuse may result in personal injury or
property damage, including damage to
the machine.
Warning!
Minors should never be allowed to use
this power tool. Bystanders, especially
children, and animals should not be
allowed in the area where it is in use.
FS 90, FS 90 R
3
English
Warning!
To reduce the risk of injury to bystanders and damage to property, never let
your power tool run unattended. When it
is not in use (e.g. during a work break),
shut it off and make sure that unauthorized persons do not use it.
Most of these safety precautions and
warnings apply to the use of all STIHL
trimmers / brushcutters. Different
models may have different parts and
controls. See the appropriate section of
your instruction manual for a description
of the controls and the function of the
parts of your model.
Safe use of a trimmer / brushcutter
involves
1. the operator
2. the power tool
3. the use of the power tool.
THE OPERATOR
Physical Condition
You must be in good physical condition
and mental health and not under the
influence of any substance (drugs,
alcohol, etc.) which might impair vision,
dexterity or judgment. Do not operate
this machine when you are fatigued.
Warning!
Be alert – if you get tired, take a break.
Tiredness may result in loss of control.
Working with any power tool can be
strenuous. If you have any condition
that might be aggravated by strenuous
work, check with your doctor before
operating this machine.
Warning!
Prolonged use of a power tool (or other
machines) exposing the operator to
vibrations may produce whitefinger disease (Raynaud's phenomenon) or
carpal tunnel syndrome.
These conditions reduce the hand's
ability to feel and regulate temperature,
produce numbness and burning
sensations and may cause nerve and
circulation damage and tissue necrosis.
All factors which contribute to
whitefinger disease are not known, but
cold weather, smoking and diseases or
physical conditions that affect blood
vessels and blood transport, as well as
high vibration levels and long periods of
exposure to vibration are mentioned as
factors in the development of whitefinger
disease. In order to reduce the risk of
whitefinger disease and carpal tunnel
syndrome, please note the following:
– Most STIHL power tools are
available with an anti-vibration
("AV") system designed to reduce
the transmission of vibrations
created by the machine to the
operator's hands. An AV system is
recommended for those persons
using power tools on a regular or
sustained basis.
– Wear gloves and keep your hands
warm.
– Keep the AV system well
maintained. A power tool with loose
components or with damaged or
worn AV elements will tend to have
higher vibration levels.
– Maintain a firm grip at all times, but
do not squeeze the handles with
constant, excessive pressure. Take
frequent breaks.
All the above-mentioned precautions do
not guarantee that you will not sustain
whitefinger disease or carpal tunnel
syndrome. Therefore, continual and
regular users should closely monitor the
condition of their hands and fingers. If
any of the above symptoms appear,
seek medical advice immediately.
Warning!
The ignition system of the STIHL unit
produces an electromagnetic field of a
very low intensity. This field may interfere with some pacemakers. To reduce
the risk of serious or fatal injury, persons
with a pacemaker should consult their
physician and the pacemaker manufacturer before operating this tool.
4
FS 90, FS 90 R
English
Proper Clothing
To reduce the risk of injury, the operator
should wear proper protective apparel.
Warning!
The deflector provided with your power
tool will not protect the operator from all
foreign objects (gravel, glass, wire, etc.)
thrown back by the rotating cutting
attachment. Thrown objects may also
ricochet and strike the operator.
Warning!
To reduce the risk of
injury to your eyes never
operate your power tool
unless wearing goggles
or properly fitted protec-
tive glasses with
adequate top and side protection complying with ANSI Z 87.1 (or your
applicable national standard). To
reduce the risk of injury to your face
STIHL recommends that you also wear
a face shield or face screen over your
goggles or protective glasses.
Wear an approved safety hard hat to
reduce the risk of injury to your head
when there is a danger of head injuries.
Power tool noise may damage your
hearing. Wear sound barriers (ear plugs
or ear mufflers) to protect your hearing.
Continual and regular users should
have their hearing checked regularly.
Be particularly alert and cautious when
wearing hearing protection because
your ability to hear warnings (shouts,
alarms, etc.) is restricted.
Always wear gloves
when handling the
machine and metal
blades. Heavy-duty, nonslip gloves improve your
grip and help to protect
your hands.
Clothing must be sturdy
and snug-fitting, but allow
complete freedom of
movement. Wear long
pants made of heavy
material to help protect
your legs. Do not wear
shorts, sandals or go
barefoot.
Avoid loose-fitting jackets, scarfs,
neckties, jewelry, flared or cuffed pants,
unconfined long hair or anything that
could become caught on branches,
brush or the moving parts of the unit.
Secure hair so it is above shoulder level.
Good footing is very
important. Wear sturdy
boots with nonslip soles.
Steel-toed safety boots
are recommended.
THE POWER TOOL
For illustrations and definitions of the
power tool parts see the chapter on
"Main Parts."
Warning!
Never modify this power tool in any way.
Only attachments supplied by STIHL
and expressly approved by STIHL for
use with the specific STIHL model are
authorized. Although certain unauthorized attachments are useable with
STIHL power tools, their use may, in
fact, be extremely dangerous. For the
cutting attachments authorized by
STIHL for your unit, see the chapter
"Approved Combinations of Cutting
Attachment, Deflector, Handle and Harness" in the instruction manual or the
STIHL "Cutting Attachments, Parts &
Accessories" catalog.
If this tool is subjected to unusually high
loads for which it was not designed (e.g.
heavy impact or a fall), always check
that it is in good condition before
continuing work. Check in particular that
the fuel system is tight (no leaks) and
that the controls and safety devices are
working properly. Do not continue
operating this machine if it is damaged.
In case of doubt, have it checked by your
STIHL servicing dealer.
THE USE OF THE POWER TOOL
Transporting the Power Tool
Warning!
To reduce the risk of injury from loss of
control and blade or line contact, never
carry or transport your power tool with
the cutting attachment moving.
FS 90, FS 90 R
5
English
389BA019 KN
001BA220 KN
It may be carried only in a horizontal
position. Grip the shaft in a manner that
the machine is balanced horizontally.
Keep the hot muffler away from your
body and the cutting attachment behind
you.
Warning!
Always shut off the engine and make
sure the cutting attachment has stopped
before putting a trimmer / brushcutter
down. When transporting it in a vehicle,
properly secure it to prevent turnover,
fuel spillage and damage to the unit.
STIHL recommends that you keep
metal blades covered with the transport
guard (optional accessory).
Fuel
Your STIHL power tool uses an oilgasoline mixture for fuel (see the
chapter on "Fuel" of your instruction
manual).
Warning!
Gasoline is an extremely
flammable fuel. If spilled
and ignited by a spark or
other ignition source, it
can cause fire and seri-
ous burn injury or
property damage. Use extreme caution
when handling gasoline or fuel mix. Do
not smoke or bring any fire or flame near
the fuel or the power tool. Note that
combustible fuel vapor may escape
from the fuel system.
Fueling Instructions
Warning!
To reduce the risk of serious injury from
burns, never attempt to refuel the unit
until it has been completely removed
from the operator.
Warning!
Fuel your power tool in well-ventilated
areas, outdoors. Always shut off the
engine and allow it to cool before refueling. Gasoline vapor pressure may
build up inside the fuel tank depending
on the fuel used, the weather conditions
and the tank venting system.
In order to reduce the risk of burns and
other personal injury from escaping gas
vapor and fumes, remove the fuel filler
cap on your power tool carefully so as to
allow any pressure build-up in the tank
to release slowly. Never remove the fuel
filler cap while the engine is running.
Select bare ground for fueling and move
at least 10 feet (3 m) from the fueling
spot before starting the engine. Wipe off
any spilled fuel before starting your
machine.
Warning!
Check for fuel leakage
while refueling and during operation. If fuel
leakage is found, do not
start or run the engine
until the leak is fixed and
any spilled fuel has been wiped away.
Take care not to get fuel on your clothing. If this happens, change your
clothing immediately.
Different models may be equipped with
different fuel caps.
Toolless cap with grip
Warning!
In order to reduce the risk of fuel spillage and fire from an improperly
tightened fuel cap, correctly position
and tighten the fuel cap in the fuel tank
opening.
To do this with this STIHL cap, raise the
grip on the top of the cap until it is upright
at a 90° angle. Insert the cap in the fuel
tank opening with the raised positioning
6
FS 90, FS 90 R
English
001BA227 KN
001BA226 KN
marks on the grip of the cap and on the
fuel tank opening lining up. Using the
grip, press the cap down firmly while
turning it clockwise as far as it will go
(approx. 1/4 turn).
Fold the grip flush with
the top of the cap. Grip
the cap and check for
tightness. If the grip does
not lie completely flush
with the cap and the
detent on the grip does
not fit in the corresponding recess in the filler
opening, or if the cap is
loose in the filler opening,
the cap is not properly
seated and tightened and
you must repeat the
above steps.
Misaligned, damaged or broken cap
N If the cap does not drop fully into the
opening when the positioning marks
line up and/or if the cap does not
tighten properly when twisted, the
base of the cap may be prematurely
rotated (vis-à-vis the top) to the
closed position. Such misalignment
can result from handling, cleaning
or an improper attempt at
tightening.
Left: Base of cap in closed posi-
tion (with open space)
Right: Base of cap correctly posi-
tioned for installation
N To return the cap to the open
position for installation, turn the cap
(with the grip up) until it drops fully
into the tank opening. Next, twist the
cap counterclockwise as far as it will
go (approx. 1/4 turn) – this will twist
the base of the cap into the correct
position. Then, twist the cap
clockwise, closing it normally.
N If your cap still does not tighten
properly, it may be damaged or
broken; immediately stop use of the
unit and take it to your authorized
STIHL dealer for repair.
Screw Cap
Warning!
Unit vibrations can cause
an improperly tightened
fuel filler cap to loosen or
come off and spill quantities of fuel. In order to
reduce the risk of fuel
spillage and fire, tighten the fuel filler
cap by hand as securely as possible.
See also the "Fueling" chapter in your
Instruction Manual for additional
information.
Before Starting
Warning!
Always check your power tool for proper
condition and operation before starting,
particularly the throttle trigger, throttle
trigger lockout, slide control / stop
switch, cutting attachment, deflector
and harness. The throttle trigger must
move freely and always spring back to
the idle position. Never attempt to modify the controls or safety devices.
Warning!
Never operate your power tool if it is
damaged, improperly adjusted or maintained, or not completely or securely
assembled.
FS 90, FS 90 R
7
English
A
000BA006 KN
B
000BA007 KN
Warning!
Do not attach any cutting attachment to
a unit without proper installation of all
required parts. Failure to use the proper
parts may cause the blade or head to fly
off and seriously injure the operator or
bystanders.
Warning!
The cutting attachment must be properly tightened and in safe operating
condition. Inspect for loose parts (nuts,
screws, etc.) and for cracked or damaged heads or cracked, bent, warped or
damaged blades. Replace damaged
heads or blades before using the power
tool. Always keep blades sharp.
Keep the handles clean and dry at all
times; it is particularly important to keep
them free of moisture, pitch, oil, fuel mix,
grease or resin in order for you to
maintain a firm grip and properly control
your power tool.
Warning!
Check that the spark plug boot is
securely mounted on the spark plug – a
loose boot may cause arcing that could
ignite combustible fumes and cause a
fire.
Warning!
To reduce the risk
of personal injury
to the operator
from blade or line
contact and
thrown objects, make sure your unit is
equipped with the proper deflector, handle and harness for the type of cutting
attachment being used (see chart in the
chapter on "Approved Combinations of
Cutting Attachment, Deflector, Handle
and Harness").
As can be seen in that chart, some
cutting attachments may require you to
change your deflector, handle and / or
harness.
Keep the deflector (and the attached
skirt where appropriate) adjusted
properly at all times (see chapters on
"Mounting the Deflector" and "Mounting
the Cutting Attachment" of your
instruction manual).
Arrows on the deflector (A) and limit
stop (B) (as seen from the underside)
show the correct direction of rotation of
the cutting attachment. When viewed
from above, however, the cutting
attachment rotates counterclockwise.
Adjust carrying harness and hand grip to
suit your size before starting work. The
machine should be properly balanced as
specified in your instruction manual for
proper control and less fatigue in
operation. To be better prepared in case
of an emergency, practice releasing the
unit from the harness as quickly as
possible.
Starting
Start the engine at least 10 feet (3 m)
from the fueling spot, outdoors only.
For specific starting instructions, see the
appropriate section of your manual.
Place the power tool on firm ground or
8
FS 90, FS 90 R
English
002BA055 KN
002BA054 KN
other solid surface in an open area.
Maintain good balance and secure
footing.
Warning!
To reduce the risk of injury from blade or
line contact, be absolutely sure that the
cutting attachment is clear of you and all
other obstructions and objects, including the ground, because when the
engine starts at starting-throttle, engine
speed will be fast enough for the clutch
to engage and move the cutting
attachment.
Once the engine has started,
immediately blip the throttle trigger,
which should release the starting throttle
and allow the engine to slow down to
idle.
With the engine running only at idle,
attach the power tool to the spring hook
of your harness (see appropriate
chapter of this manual).
Warning!
Your power tool is a one-person
machine. Do not allow other persons in
the general work area, even when
starting.
Warning!
To reduce the risk of injury from loss of
control, do not attempt to "drop start"
your power tool.
Warning!
When you pull the starter grip, do not
wrap the starter rope around your hand.
Do not let the grip snap back, but guide
the starter rope to rewind it properly.
Failure to follow this procedure may
result in injury to your hand or fingers
and may damage the starter
mechanism.
Important Adjustments
Warning!
To reduce the risk of personal injury
from loss of control or contact with the
running cutting attachment, do not use
your unit with incorrect idle adjustment.
At correct idle speed, the cutting attachment should not move. For directions on
how to adjust idle speed, see the appropriate section of your instruction
manual.
If you cannot set the correct idle speed,
have your STIHL dealer check your
power tool and make proper
adjustments and repairs.
During Operation
Holding and Controlling the Power
Tool
Always hold the unit firmly with both
hands on the handles while you are
working. Wrap your fingers and thumbs
around the handles, keeping the
handles cradled between your thumb
and forefinger. Keep your hands in this
position to have your power tool under
control at all times. Make sure your
trimmer handles and grips are in good
condition and free of moisture, pitch, oil,
fuel mix or grease.
FS 90, FS 90 R
9
English
Warning!
Never attempt to operate
your power tool with one
hand. Loss of control of
the power tool resulting in
serious or fatal injury may
result. To reduce the risk
of cut injuries, keep hands and feet
away from the cutting attachment.
Never touch a moving cutting attachment with your hand or any other part of
your body.
Warning!
Do not overreach. Keep proper footing
and balance at all times. Special care
must be taken in slippery conditions
(wet ground, snow) and in difficult, overgrown terrain. Watch for hidden
obstacles such as tree stumps, roots
and ditches to avoid stumbling. For better footing, clear away scrub and
cuttings. Be extremely cautious when
working on slopes or uneven ground.
Warning!
To reduce the risk of injury from loss of
control, never work on a ladder or on
any other insecure support. Never hold
the cutting attachment above waist
height.
Working Conditions
Operate and start your power tool only
outdoors in a well ventilated area.
Operate it under good visibility and
daylight conditions only. Work carefully.
Warning!
As soon as the engine is
running, this product generates toxic exhaust
fumes containing chemicals, such as unburned
hydrocarbons (including
benzene) and carbon monoxide, that
are known to cause respiratory problems, cancer, birth defects, or other
reproductive harm. Some of the gases
(e.g. carbon monoxide) may be colorless and odorless. To reduce the risk of
serious or fatal injury / illness from inhaling toxic fumes, never run the machine
indoors or in poorly ventilated locations.
Warning!
If the vegetation being cut or the surrounding ground is coated with a
chemical substance (such as an active
pesticide or herbicide), read and follow
the instructions and warnings that
accompanied the substance at issue.
Warning!
Inhalation of certain dusts, especially
organic dusts such as mold or pollen,
can cause susceptible persons to have
an allergic or asthmatic reaction. Substantial or repeated inhalation of dust
and other airborne contaminants, in particular those with a smaller particle size,
may cause respiratory or other illnesses. Control dust at the source
where possible. Use good work practices, such as operating the unit so that
the wind or operating process directs
any dust raised by the power tool away
from the operator. Follow the recommendations of EPA / OSHA / NIOSH
and occupational and trade associations with respect to dust ("particulate
matter"). When the inhalation of dust
cannot be substantially controlled, i.e.,
kept at or near the ambient (background) level, the operator and any
bystanders should wear a respirator
approved by NIOSH / MSHA for the type
of dust encountered.
Operating Instructions
Warning!
Do not operate your power tool using
the starting throttle lock, as you do not
have control of the engine speed.
In the event of an emergency, shut off
the engine immediately – move the slide
control / stop switch to 0 or STOP.
10
FS 90, FS 90 R
English
15m (50ft)
Warning!
The cutting attachment
continues to rotate for a
short period after the
throttle trigger is released
(flywheel effect).
Warning!
The rotating cutting attachment may
fling foreign objects directly or by ricochet a great distance.
To reduce the risk of eye and other injury
always wear proper eye protection (see
the chapter on "Proper Clothing") and
ensure that bystanders are at least
50 feet (15 m) away. To reduce the risk
of damage to property, also maintain this
distance from such objects as vehicles
or windows. Any coworkers who must be
in the restricted area should also wear
goggles or protective glasses. Stop the
engine immediately if you are
approached.
Warning!
Before you start work,
examine the area for
stones, glass, fence wire,
metal, trash or other solid
objects. The cutting
attachment could throw
objects of this kind.
Warning!
This trimmer / brushcutter is normally to
be used at ground level with the cutting
attachment parallel to the ground. Use
of a trimmer / brushcutter above ground
level or with the cutting attachment perpendicular to the ground may increase
the risk of injury, since the cutting
attachment is more fully exposed and
the power tool may be more difficult to
control. Never use your trimmer / brushcutter as a hedge trimmer.
Warning!
During cutting, check the tightness and
the condition of the cutting attachment
at regular short intervals with the engine
and attachment stopped. If the behavior
of the attachment changes during use,
stop the engine immediately, wait until
the cutting attachment stops, and check
the nut securing the attachment for
tightness and the blade or head for
cracks, wear and damage.
Warning!
A loose blade or head may vibrate,
crack, break or come off the trimmer /
brushcutter, which may result in serious
or fatal injury. Make sure that the cutting
attachment is properly tightened. Use
the wrench supplied or one of sufficient
length to obtain the proper torque. If the
blade or head loosens after being properly tightened, stop work immediately.
The retaining nut may be worn or damaged and should be replaced. If the
blade or head continues to loosen, see
your STIHL dealer. Never use a trimmer
/ brushcutter with a loose cutting
attachment.
Warning!
Replace a cracked, damaged or wornout head or a cracked, bent, warped,
damaged, dull or worn out blade immediately, even if damage is limited to
superficial cracks. Such attachments
may shatter at high speed and cause
serious or fatal injury.
Warning!
When using rigid blades, avoid cutting
close to fences, sides of buildings, tree
trunks, stones or other such objects that
could cause the power tool to kick out or
could cause damage to the blade.
STIHL recommends use of the nylon
line heads for such jobs. In addition, be
alert to an increased possibility of ricochets in such situations.
FS 90, FS 90 R
11
English
Warning!
If the head, blade or deflector becomes
clogged or stuck, always shut off the
engine and make sure the cutting
attachment has stopped before cleaning. Grass, weeds, etc. should be
cleaned off the blade or from around the
head at regular intervals.
Warning!
To reduce the risk of unintentional rotation of the cutting attachment and injury,
always shut off the engine and remove
the spark plug boot before replacing the
cutting attachment. To reduce the risk of
injury, always shut off the engine before
adjusting the length of the nylon line on
manually adjustable mowing heads.
Warning!
The gearbox becomes hot during operation. To reduce the risk of burn injury,
do not touch the gear housing when it is
hot.
Warning!
The muffler and other parts of the
engine (e.g. fins of the cylinder, spark
plug) become hot during operation and
remain hot for a while after stopping the
engine. To reduce risk of burns do not
touch the muffler and other parts while
they are hot.
Warning!
To reduce the risk of fire and burn injury,
keep the area around the muffler clean.
Remove excess lubricant and all debris
such as pine needles, branches or
leaves. Let the engine cool down sitting
on concrete, metal, bare ground or solid
wood away from any combustible
substances.
Warning!
Never modify your muffler. The muffler
could be damaged and cause an
increase in heat radiation or sparks,
thereby increasing the risk of fire and
burn injury. You may also permanently
damage the engine. Have your muffler
serviced and repaired by your STIHL
servicing dealer only.
Catalytic Converter
Warning!
Some STIHL power tools
are equipped with a cata-
lytic converter, which is
designed to reduce the
exhaust emissions of the
engine by a chemical
process in the muffler. Due to this process, the muffler does not cool down as
rapidly as conventional mufflers when
the engine returns to idle or is shut off.
To reduce the risk of fire and burn injuries, the following specific safety
precautions must be observed.
Warning!
Since a muffler with a catalytic converter
cools down less rapidly than conventional mufflers, always set your power
tool down in the upright position and
never locate it where the muffler is near
dry brush, grass, wood chips or other
combustible materials while it is still hot.
Warning!
An improperly mounted or damaged cylinder housing or a damaged / deformed
muffler shell may interfere with the cooling process of the catalytic converter.
To reduce the risk of fire or burn injury,
do not continue work with a damaged or
improperly mounted cylinder housing or
a damaged / deformed muffler shell.
Your catalytic converter is furnished with
screens designed to reduce the risk of
fire from the emission of hot particles.
Due to the heat from the catalytic
reaction, these screens will normally
stay clean and need no service or
maintenance. If you experience loss of
performance and you suspect a clogged
screen, have your muffler maintained by
a STIHL servicing dealer.
USING THE CUTTING ATTACHMENT
For an illustration of the various cutting
attachments and instructions on proper
mounting see the chapter on "Mounting
the Cutting Attachment" in your
instruction manual.
12
FS 90, FS 90 R
Warning!
002BA354 KN
002BA177 KN
To reduce the risk of severe or fatal
injury from blade contact and / or loss of
control, never attempt to use a metal
blade on an FS model for which it is not
authorized.
Using the Mowing Heads
Do not use with mowing line longer than
the intended length. With a properly
mounted deflector, the built-in linelimiting blade will automatically adjust
the line to its proper length.
Using the unit with an overly long nylon
cutting line increases the load on the
engine and reduces its operating speed.
This causes the clutch to slip
continuously and results in overheating
and damage to important components
(e.g. clutch, polymer housing
components). Such damage could,
among other things, cause the cutting
attachment to rotate at idle.
Mowing heads are to be used only on
trimmers / brushcutters equipped with a
line-limiting blade in the deflector in
order to keep the line at the proper
length (see "Main Parts" chapter in your
instruction manual).
If the lawn edges are planted with trees
or bordered by a fence etc., it is best to
use a nylon line head. It achieves a
"softer" cut with less risk of damaging
tree bark etc. than polymer blades.
However, the polymer-bladed STIHL
PolyCut produces a better cut if there
are no plants along the edge of the lawn.
Sharpening is not necessary, and worn
polymer blades are easily replaced.
Warning!
To reduce the risk of serious injury,
never use wire or metal-reinforced line
or other material in place of the nylon
cutting lines. Pieces of wire could break
off and be thrown at high speed toward
the operator or bystanders.
STIHL SuperCut mowing head
Fresh line is advanced automatically.
Frayed line is replaced by a simple
adjustment (see instruction sheet
supplied with mowing head).
STIHL AutoCut mowing head
Nylon cutting line advances
automatically when tapped against the
ground (TapAction).
STIHL TrimCut mowing head
Frayed line is replaced by a simple
adjustment (see instruction sheet
supplied with mowing head).
STIHL PolyCut mowing head
Uses either nylon lines or nonrigid,
pivoting polymer blades.
Observe wear indicators.
English
Warning!
Three rectangular wear limit marks are
applied to the base (periphery) of the
PolyCut. To reduce the risk of serious
injury from breakage of the head or
blades, the PolyCut must not be used
when it has worn as far as one of these
marks. It is important to follow the maintenance instructions supplied with the
head.
STIHL FixCut mowing head
Uses pre-cut lengths of nylon line.
Observe wear indicators.
Do not continue using the mowing head
if the raised moldings (1) on the base
are missing or worn – see right
illustration above. The mowing head
may otherwise shatter and flying objects
could result in injury to the operator or
bystanders. Install a new mowing head.
FS 90, FS 90 R
13
English
002BA135 KN
002BA355 KN
002BA066 KN
Risk of Kickout (Blade Thrust) with all
Rigid Cutting Blades
Warning!
Kickout (blade thrust) is the sudden and
uncontrolled motion towards the operator's right or rear that can occur when
the shaded area (especially the darkly
shaded area) of a rotating blade comes
in contact with a solid rigid object like a
tree, rock, bush or wall. The rapid counterclockwise rotation of the blade may
be stopped or slowed, and the cutting
attachment may be thrown to the right or
to the rear.
This kickout (blade thrust) may cause
loss of control of the power tool and may
result in serious or fatal injury to the
operator or bystanders. To reduce the
risk of injury, extreme caution should be
used when cutting with the shaded area
of any rigid blade.
Using the Grass Cutting Blade
All kinds of grass and weeds can be
easily cut with the grass cutting blade.
The power tool is swept in an arc similar
to a scythe.
Warning!
To reduce the risk of serious or fatal
injury from blade breakage, never
attempt to use this blade to cut woody
materials.
The 4-tooth grass cutting blade is
intended to cut grass and weeds. It has
4 cutting knives with cutting edges on
both sides, i.e. front and rear. When the
cutting edges on one side become dull,
the blade can be turned over to utilize
the cutting edges on the other side.
The 8-tooth grass cutting blade is
recommended for cutting fern or reed.
Both types of grass cutting blade have to
be resharpened when all cutting edges
are dull.
Using the Brush Knife
When fitted to the power tool, the brush
knife is suitable for applications ranging
from cutting matted grass to clearing
weeds, wild growth and scrub.
To cut wild growth and scrub, lower the
rotating brush knife down onto the
growth to achieve a chopping effect –
but keep the tool below waist height at
all times.
Warning!
Exercise extreme caution when using
this method of cutting. The higher the
cutting attachment is off the ground, the
greater the risk of loss of control and of
cuttings being thrown sideways.
Use the power tool like a scythe to cut
grass, i.e. sweep it to and fro in an arc.
Warning!
When cutting woody materials, use the
left side of the blade to avoid "kickout"
(blade thrust) situations.
Warning!
Improper use of a brush knife may
cause it to crack, chip or shatter.
Thrown blade fragments may seriously
or fatally injure the operator or bystanders. To reduce the risk of injury, avoid
contact with hard or solid foreign objects
such as stones, rocks or pieces of
metal.
14
FS 90, FS 90 R
English
000BA016 KN
002BA214 ST
Warning!
When cutting young saplings or other
woody materials up to 2 cm (3/4 in.) in
diameter, use the left side of the blade
to avoid "kickout" situations (see section
on "Risk of kickout (blade thrust) with all
rigid cutting blades"). Do not attempt to
cut woody material with a larger diameter, since the blade may catch or jerk the
power tool forward. This may cause
damage to the blade or power tool or
loss of control of the power tool, resulting in personal injury. Use a circular saw
blade for such work.
Warning!
Inspect the brush knife at regular short
intervals for signs of damage. Do not
continue working with a damaged brush
knife. Resharpen the brush knife regularly (when it has dulled noticeably).
Using the Circular Saw Blade
Circular saw blades are suitable for
thinning brush and cutting small trees up
to a diameter of 4 cm (1 1/2 in.). Do not
attempt to cut trees with larger
diameters, since the blade may catch or
jerk the trimmer / brushcutter forward.
This may cause damage to the blade or
loss of control of the power tool and
result in serious injury. Use a chain saw
for such work.
standard deflector be removed and
replaced by the special limit stop
deflector (see chapter on "Mounting the
Deflector"). This limit stop helps to keep
the unit positioned against the tree
during the cutting process.
Inexperienced users should place the
left side of the stop against the tree trunk
before beginning to cut. This will keep
the trimmer / brushcutter against the tree
during the cutting operation and will
reduce the risk of loss of control and
possible kickout (described above and
briefly again below).
Before starting the cut, accelerate the
engine up to full throttle. Perform cut
with uniform pressure. STIHL
recommends that the circular saw blade
be applied to the right of the tree, using
the non-shaded area of the blade, as
shown in the illustration above.
FS 90, FS 90 R
Warning!
To reduce the risk that the blade will
crack and / or break, avoid all contact
with stones, rocks or the ground.
Sharpen blades in a timely manner as
specified – dull teeth may cause the
blade to crack or shatter.
When a trimmer / brushcutter with a
circular saw blade is used to cut down
small trees, STIHL recommends that the
15
English
002BA068 KN
Warning!
The risk of kickout is highest when cutting in the darker shaded area. To
reduce the risk of kickout and resulting
injury, do not use this area of the circular
saw blade for cutting trees or shrubs.
Special techniques using the lighter
shaded areas of the blade to cut shrubs
and trees should only be used by experienced operators with specialized
training in the use and control of the
trimmer / brushcutter.
Warning!
To reduce the risk of loss of control and
serious injury to the operator or
bystanders by a kickout, never use a circular saw blade on a trimmer /
brushcutter with a loop handle, but
rather only on one with a bicycle handle.
When felling small trees, maintain a
distance of at least two tree lengths from
the nearest coworker.
Warning!
In order to reduce the risk of injury from
thrown objects or operator contact with
the blade or head, be sure to remount
the standard deflector when no longer
using a circular saw blade.
MAINTENANCE, REPAIR AND
STORING
Maintenance, replacement, or repair
of the emission control devices and
systems may be performed by any
nonroad engine repair establishment
or individual. However, if you make a
warranty claim for a component
which has not been serviced or
maintained properly or if
nonapproved replacement parts were
used, STIHL may deny coverage.
Warning!
Use only identical STIHL replacement
parts for maintenance and repair. Use of
non-STIHL parts may cause serious or
fatal injury.
Strictly follow the maintenance and
repair instructions in the appropriate
sections of your instruction manual.
Warning!
Always stop the engine and make sure
that the cutting attachment is stopped
before doing any maintenance or repair
work or cleaning the power tool. Do not
attempt any maintenance or repair work
not described in your instruction manual. Have such work performed by your
STIHL servicing dealer only.
Wear gloves when handling or
performing maintenance on blades.
Warning!
Use the specified spark plug, and make
sure it and the ignition lead are always
clean and in good condition. Always
press the spark plug boot snugly onto
the spark plug terminal of the proper
size. (Note: If the terminal has a detachable SAE adapter nut, it must be
securely attached.) A loose connection
between the spark plug and the ignition
wire connector in the boot may create
arcing that could ignite combustible
fumes and cause a fire.
Warning!
Never test the ignition system with the
spark plug boot removed from the spark
plug or with a removed spark plug, since
uncontained sparking may cause a fire.
Warning!
Do not operate your power tool if the
muffler is damaged, missing or modified. An improperly maintained muffler
will increase the risk of fire and hearing
loss. If your muffler was equipped with a
spark-arresting screen to reduce the
risk of fire, never operate your power
tool if the screen is missing or damaged.
Remember that the risk of forest fires is
greater in hot or dry weather.
Warning!
Never repair damaged cutting attachments by welding, straightening or
modifying the shape. This may cause
parts of the cutting attachment to come
off and result in serious or fatal injuries.
16
FS 90, FS 90 R
Keep blades sharp. Tighten all nuts,
bolts and screws, except the carburetor
adjustment screws, after each use.
Do not clean your machine with a
pressure washer. The solid jet of water
may damage parts of the machine.
Store the power tool in a dry and high or
locked location out of reach of children.
Before storing for longer than a few
days, always empty the fuel tank. See
chapter "Storing the Machine" in the
instruction manual.
English
FS 90, FS 90 R
17
English
24
13
12
249BA064 KN
1
2
6
7
3
8
18
17
20
22
21
4
23
15
19
18
19
20
20
16
10
11
5
9
14
22
23
23
Approved Combinations of Cutting Attachment, Deflector, Handle and Harness
Cutting attachment Deflector Handle Harness
18
FS 90, FS 90 R
English
Permissible combinations
The complete equipment comprises:
– Cutting attachment
– Deflector
– Handle
– Harness
Choose the proper combination from the
table depending on the cutting
attachment. Read the table horizontally
from left to right.
Cutting attachments
Mowing heads
1 STIHL SuperCut 20-2
2 STIHL AutoCut C 25-2
3 STIHL AutoCut 25-2
4 STIHL TrimCut 31-2
5 STIHL FixCut 25-2
6 STIHL PolyCut 20-3
Metal cutting attachments
7 Grass cutting blade 230-4
8 Grass cutting blade 230-8
9 Brush knife 250-3
10 Circular saw blade 200 scratcher
tooth
11 Circular saw blade 200 chisel tooth
Circular saw blades of other, nonmetal materials must not be used.
14 Skirt and blade for all mowing heads
(see “Mounting the deflector”)
15 Deflector without skirt and blade for
all metal mowing tools and brush
knives
16 Limit stop for circular saw blades
Handles
17 Loop handle
18 Loop handle with
19 Barrier bar
20 Bike handle
Harnesses
21 Shoulder strap can be used
22 Shoulder strap must be used
23 Full harness can be used
24 Full harness must be used
Warning!
Based on the cutting attachment being
used:
Choose the proper deflector in order to
reduce the risk of injury from thrown
objects and contact with the cutting
attachment.
Make sure your unit is equipped with the
proper handle and harness in order to
reduce the risk of injury from loss of control and contact with the cutting
attachment.
Use grass cutting metal blades and
brush knifes on this unit only if equipped
with a bike handle or a loop handle with
barrier bar.
Use circular saw blades on this unit only
if equipped with a bike handle.
Do not use rigid plastic blades on this
unit.
Deflectors, stop
12 Deflector only for mowing heads
13 Deflector with
FS 90, FS 90 R
19
English
228BA047 KN
BF
FH
FCS
KB
KW
HT
Approved Power Tool
Attachments
The following STIHL interchangeable
attachments may be mounted on the
basic machine:
Interchangeable
2)
Use
Soil cultivator
Edger
Scrub cutter
Hedge trimmer
Hedge trimmer
Pole pruner
Bristle brush
Sweeper drum
attachment
1)
BF
2) 3)
FCS
1)
FH
2)
HL 0°
HL 135°
HT
1) 2)
2)
KB (4601)
KW (4601)
2)
assembly
1)
stop (barrier bar) on loop handle is
required
2)
not approved for machines with
bicycle handle
3)
harness need not be used
Mounting the Bike Handle
Attaching the bicycle handle with
rotating handlebar support
The machine is delivered with the
rotating handlebar support already
attached to the shaft. The clamps must
be removed in order to attach the
handlebar.
Removing the clamps
20
N hold onto the lower (1) and upper
clamps (2)
N Unscrew the tommy screw (3) –
after the tommy screw has been
unscrewed, the parts are loose and
are pressed apart by the two
springs (4, 5)!
FS 90, FS 90 R
English
1
7
A
250BA046 KN
002BA234 KN
8
N Remove the tommy screw –
washer (6) remains on the tommy
screw
N Separate clamps – springs (4, 5)
remain in the lower clamp!
Fastening the handlebar
N Position the handlebar (7) in the
lower clamp (1) so that distance (A)
is not more than 6 in. (15 cm)
N Place the upper clamp on top and
hold both clamps together
N Insert the tommy screw with the
washer on it through both clamps as
far as it will go – hold all parts
together and secure them
N Position the entire secured
assembly on the handlebar
support (8) with the tommy screw
facing the motor
N Press the tommy screw into the
handlebar support as far as it will go
and then screw it in – do not tighten
it down yet
N Align the handlebar so that it is
perpendicular to the shaft – check
distance (A)
N Tighten tommy screw
Attaching the control handle
N Unscrew the bolt (9) – the nut (10)
remains in the control handle (11)
N Push the control handle with the
throttle trigger (12) facing toward
the gearbox onto the end of the
handlebar (7) until the holes (13)
align
N Screw in and tighten the bolt (9)
Fastening the throttle cable
Do not kink the throttle cable or
run it in tight radiuses – the
throttle trigger must move freely!
FS 90, FS 90 R
21
English
15
14
15
14
15
250BA002 KN
2
002BA098 KN
1
1
N Press throttle cable (14) into the
throttle cable support (15)
Adjusting the throttle cable
N Check throttle cable adjustment –
see "Adjusting the throttle cable"
Swiveling the handlebar
Into the transport position
N Loosen the tommy screw (3) and
unscrew it until it is possible to
swivel the handlebar (7) clockwise
N Turn the handle bar 90° and then
swivel it downward
N Tighten tommy screw (3)
Into the working position
N Swivel and turn the handlebar
counterclockwise in the opposite of
the order described above
Mounting the Loop Handle
Loop handle with barrier bar
N Fit the square nuts (1) in the barrier
bar (2); the holes must line up.
22
FS 90, FS 90 R
English
5
4
002BA099 KN
2
3
6
7
4
5
002BA136 KN
1
6
1
3
8
7
8
7
10
9
4
002BA147 KN
A
N Fit the clamp (3) in the loop
handle (4) and place them both on
the drive tube (5).
N Place the clamp (6) in position.
N Place the barrier bar (2) in position
as shown.
N Line up the holes.
N Insert the screws (7) and tighten
them down moderately against the
barrier bar.
N Go to "Securing the loop handle".
Loop handle without barrier bar
N Fit the clamp (3) in the loop
handle (4) and place them both on
the drive tube (5).
N Place the clamp (6) in position.
N Line up the holes.
N Fit washers (7) on the screws (8)
and insert the screws in the holes.
Fit the square nuts (1) and screw
them down as far as stop.
N Go to "Securing the loop handle".
Securing the loop handle
N Secure the loop handle (4) about
20cm/8in (A) forward of the control
handle (9).
N Line up the loop handle.
N Tighten down the screws firmly –
lock the nuts if necessary.
The sleeve (10) (not fitted on all models)
must be between the loop handle and
the control handle.
FS 90, FS 90 R
23
English
002BA163 KN
STOP
249BA017 KN
1
2
002BA142 KN
1
2
1
002BA380 KN
2
1
3
3
Adjusting the Throttle
Cable
Some machine versions are equipped
with a throttle cable adjuster on the
control handle.
A properly adjusted throttle cable is the
precondition for correct operation in the
full throttle, starting throttle and idle
positions.
Adjust the throttle cable only after the
unit is fully assembled – the control
handle must be in the normal operating
position.
N Use a suitable tool to push the slide
to the end of the slot (see
illustration).
N Press down the throttle trigger
lockout (1) and squeeze the throttle
trigger (2) (full throttle) – this sets
the throttle cable correctly.
Fitting the Carrying Ring
The carrying ring comes standard with
the machine or is available as a special
accessory.
For position of carrying ring see "Main
Parts".
N Place the clamp (1) against the
drive tube with the tapped hole on
the left (viewed from engine).
N Squeeze the two ends of the clamp
together and hold in that position.
N Insert the M6x14 screw (2).
N Line up the carrying ring.
N Tighten down the screw firmly.
Mounting the Deflector
Mounting the Deflector
1 Deflector for mowing attachments
2 Deflector for mowing heads
Deflectors (1) and (2) are both mounted
to the gearbox in the same way.
N Place the deflector on the gearbox
flange.
N Insert the screws (3) and tighten
them down firmly.
24
FS 90, FS 90 R
English
4
1
5
4
002BA103 KN
7
002BA382 KN
6
002BA104 KN
Fitting the Skirt and Blade
These parts must be fitted to the
deflector (1) when you use a
mowing head.
N Slide the lower guide slot of the skirt
(4) onto the deflector (1) – it must
snap into position.
N Push the blade (5) into the upper
guide slot on the skirt and line it up
with the first hole.
N Insert the screw and tighten it down
firmly.
Mounting the Limit Stop
Always fit the limit stop (6) when
you use a circular saw blade.
N Position the limit stop (6) on the
gearbox flange.
N Insert the screws (7) and tighten
them down firmly.
Mounting the Cutting
Attachment
Preparations
N Lay your brushcutter on its back so
that the cutting attachment
mounting face is facing up.
Mounting hardware for cutting
attachments
The mounting hardware supplied
depends on the cutting attachment that
comes as original equipment with the
new machine.
Mounting hardware is not packed
with machine
Only mowing heads can be mounted.
FS 90, FS 90 R
25
English
2
002BA164 KN
1
3
4
5
7
8
2
002BA166 KN
7
N Pull the hose (1) (protector for
shipping) off the shaft (2).
N Go to "Mounting the mowing head".
If you want to mount a metal cutting
attachment in place of a mowing head,
you will need the following additional
parts: Nut (3), rider plate (4) and thrust
washer (5) (special accessories).
Mounting hardware is packed with
machine
Mowing heads and metal cutting
attachments may be mounted.
If the parts are packed with the
machine
N Pull the hose (1) (protector for
shipping) off the shaft (2).
The nut (3), rider plate (4) and thrust
wsher (5) are in the parts kit supplied
with the machine.
N Go to "Mounting the mowing head"
or "Mounting the metal cutting
attachment".
If the parts are mounted to the
gearbox
N Go to "Removing the mounting
hardware".
Removing the mounting hardware
N Block the shaft – see next chapter
on "Blocking the output shaft".
N Use the combination wrench (6) –
comes standard with machine or is
available as special accessory – to
unscrew the nut (3) clockwise (lefthand thread) from the shaft (2).
N Pull the thrust washer (5) off the
shaft (2).
The rider plate (4) is in the parts kit
supplied with the machine.
N Go to "Mounting the mowing head"
or "Mounting the metal cutting
attachment".
Blocking the output shaft
N Insert the stop pin (7) or screwdriver
– come standard with machine or
are available as special accessories
– in the hole (8) in the gearbox as
far as stop, and apply slight
pressure.
N Rotate the nut or cutting attachment
on the shaft (2) until the stop pin
slips into position and blocks the
shaft.
Attaching the mowing head
Keep the information sheet for the
mowing head in a safe place.
STIHL SuperCut 20-2,
STIHL AutoCut 25-2,
STIHL AutoCut C 25-2,
26
FS 90, FS 90 R
English
1
002BA081 KN
STIHL TrimCut 31-2,
STIHL FixCut 25-2,
STIHL PolyCut 20-3
N Turn the mowing head
counterclockwise until it is flush
against the shaft (1)
N Block the shaft
N Tighten the mowing head
Remove the tool used to block the
shaft.
Removing the mowing head
N Block the shaft
STIHL SuperCut 20-2,
STIHL AutoCut 25-2,
STIHL AutoCut C 25-2,
STIHL TrimCut 31-2,
STIHL FixCut 25-2,
STIHL PolyCut 20-3
N Turn the mowing head clockwise
Feed out mowing line
STIHL SuperCut
Line is fed out automatically if the
mowing line is at least 2 1/2 in. (6 cm)
long – the blade on the deflector
shortens excessively long mowing line
to optimum length.
STIHL AutoCut
N Hold the mowing head parallel
above the surface of the lawn – tap
it on the ground – approx. 1 1/4 in.
(3 cm) of mowing line is fed out
The blade on the deflector shortens
excessively long mowing line to
optimum length – thus repeated tapping
in succession is to be avoided!
Mowing line is only fed out if both
mowing lines are still at least 1in.
(2.5 cm) long!
For all other mowing lines
Proceed as described in the mowing
head information sheet.
Always switch off the engine to
fed out mowing line by hand –
otherwise there is a risk of injury!
Replacing mowing line and/or cutting
blade
Proceed as described in the mowing
head information sheet.
Mounting metal cutting attachments
The skirt and lne limiting blade are not
required on the deflector for grass
cutting blades 230-4 (1), 230-8 (2) or the
brush knife (3) – see "Mounting the
Deflector".
Fit the approriate limit stop for
circular saw blades 200 (4, 5) –
see "Mounting the deflector".
Lay your brushcutter on its back with the
cutting attachment mounting face
pointing up: The cutting edges of (1) and
(3) may point in either direction. The
cutting edges of (2), (4) and (5) must
point clockwise.
Direction of rotation is indicated by an
arrow on the inside of the mowing
attachment deflector or limit stop.
FS 90, FS 90 R
27
English
N Place the cutting attachment (6) on
the thrust plate (7).
Collar (see arrow) must engage
the mowing head's mounting hole.
N Fit the thrust washer (8) and rider
plate (9) on the shaft (10).
N Block the drive shaft.
N Use the combination wrench (12) to
screw the mounting nut (11) on to
the output shaft counterclockwise
and tighten it down firmly.
If the mounting nut turns too
freely, fit a new one.
Removing the metal cutting
attachment
N Block the drive shaft.
N Unscrew the mounting nut
clockwise.
N Take the parts off the shaft – do not
remove the thrust plate (7).
4-MIX Engine
The STIHL 4-MIX engine features
mixture lubrication and must be run on a
fuel mixture of gasoline and engine oil.
It operates otherwise on the 4-stroke
principle.
28
FS 90, FS 90 R
Loading...