STIHL FC 90 Owner's Manual
STIHL FC 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 - 39
Manual de
instrucciones
41 - 84
Contents
English
Guide to Using this Manual 2
Safety Precautions and Working
Techniques 3
Using the Unit 12
Mounting the Loop Handle 14
Adjusting the Throttle Cable 14
Mounting the Cutting Blade 15
4-MIX Engine 15
Original Instruction ManualPrinted on chlorine-free paper
Fuel 16
Fueling 17
Starting / Stopping the Engine 18
Operating Instructions 20
Cleaning the Air Filter 21
Engine Management 21
Adjusting the Carburetor 21
Spark Arresting Screen in Muffler 23
Spark Plug 23
Lubricating the Gearbox 24
Replacing the Starter Rope and
Rewind Spring 25
Storing the Machine 27
Replacing the Depth Wheel 27
Printing inks contain vegetable oils, paper can be recycled.
Replacing the Skirt 28
Replacing the Cutting Blade 28
Maintenance and Care 29
Main Parts 31
Specifications 32
Special Accessories 33
Maintenance and Repairs 34
STIHL Incorporated Federal
Emission Control Warranty
Statement 34
STIHL Incorporated California
Exhaust and Evaporative
Emissions Control Warranty
Statement 36
Trademarks 38
Allow only persons who fully understand
this manual to operate your edger.
To receive maximum performance and
satisfaction from your STIHL edger, 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
edger. 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 an edger 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 and handle for the type
of cutting attachment being used.
Always wear proper eye protection.
{
© ANDREAS STIHL AG & Co. KG, 2011
0458-237-8621-C. M2-25.A11.CP.
0000000816_002_GB
FC 90
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.
FC 90
English
Safety Precautions and
Working Techniques
Because an edger is a
high-speed, fast-cutting
power tool, 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.
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. Use only cutting
attachments that are specifically authorized by STIHL for use on your FC
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 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
blades, may result in serious or fatal
injury to the operator or bystanders.
Use your edger only for edging in grass,
weeds and soft green plants.
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.
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
edgers. Different models may have
different parts and controls. See the
appropriate section of your instruction
manual for a description of the controls
and function of the parts of your model.
Safe use of an edger 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.
FC 90
3
English
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.
Proper Clothing
Warning!
To reduce the risk of injury, the operator
should wear proper protective apparel.
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.
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.
Wear an approved safety hard hat to
reduce the risk of injury to your head
when there is a danger of head injuries.
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.
4
FC 90
English
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.
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 contact, never carry or
transport your power tool with the cutting attachment moving.
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 that the cutting attachment has
stopped before putting an edger down.
When transporting it in a vehicle, properly secure it to prevent turnover, fuel
spillage and damage to the unit.
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
FC 90
5
English
001BA220 KN
001BA227 KN
001BA226 KN
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
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 (in relation to 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.
6
FC 90
Screw Cap
002BA118 KN
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, stop switch, cutting
blade, 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. Never use a power tool that is
damaged or not properly maintained.
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 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, bent,
warped or damaged blades. Replace
damaged blades before using the power
tool.
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 contact and thrown
objects, make
sure your unit is equipped with the
proper deflector, handle and harness.
English
An arrow on the deflector shows the
correct direction of rotation of the cutting
blade.
The arrow on the deflector must always
face away from you, so that cuttings and
other debris will be diverted away from
the machine and your position (see
chapter "Working Techniques".)
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, practise releasing the
unit from the harness as quickly as
possible.
Starting
Warning!
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
other solid surface in an open area.
Maintain good balance and secure
footing.
FC 90
7
English
002BA054 KN
Warning!
To reduce the risk of injury from blade
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!
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.
Your right hand should grip the rear
handle. This also applies to left-handers.
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.
Warning!
To reduce the risk of injury from loss of
control, do not attempt to "drop start"
your power tool.
8
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.
FC 90
Warning!
15m (50ft)
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.
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
English
In the event of an emergency, switch off
the engine immediately – move the slide
control / stop switch to 0 or STOP.
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.
FC 90
Warning!
Do not operate your power tool using
the starting throttle lock, as you do not
have control of the engine speed.
9
English
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!
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 for cracks, wear
and damage.
Warning!
A loose blade may vibrate, crack, break
or come off the edger, 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 loosens after being
properly tightened, stop work immediately. The retaining nut may be worn or
damaged and should be replaced. If the
blade continues to loosen, see your
STIHL dealer. Never use an edger with
a loose cutting attachment.
Warning!
Replace 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 your edger, 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.
Warning!
If the 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 at regular
intervals.
Warning!
To reduce the risk of unintentional rotation of the cutting attachment and injury,
always shut off the engine before
replacing the cutting attachment.
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.
USING THE CUTTING ATTACHMENT
For an illustration of the cutting
attachment and instructions on proper
mounting see the chapter on "Replacing
the Cutting Blade" in your instruction
manual.
10
FC 90
Warning!
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 FC model for which it is not
authorized.
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.
English
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.
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.
FC 90
11
English
241BA000 KN
2
1
241BA001 KN
A
B
241BA002 KN
2
3
Using the Unit
Your power edger is designed to
produce sharp contoured borders
around lawns and flower beds. It will cut
almost all types of grass, weeds and soft
green plants.
Preparations
If the soil is very dry, spray it with water
before you start work: this softens the
soil a little and also reduces the amount
of dust created. Slightly damp green
plants are easier to cut.
Clear away all obstacles and solid
objects from the work area.
N Plan the best route for edging.
Always hold and operate your edger
on the right-hand side of your body.
Adjusting Cutting Depth
N To reduce the risk of injury, shut
off the engine.
N Loosen the wingnut (1)
counterclockwise.
N Adjust the wheel (2): Upwards to
increase the depth of cut (A) or
downwards to reduce the depth of
cut (A).
Adjust correctly
The depth of cut depends on the
uneveness of the ground, your height
and the way you hold the edger. Use the
following procedure:
N Adjust the depth wheel (2) so that
the blade (3) just touches the
ground or breaks the surface of the
soil by no more than 0.2 in. (5 mm)
in the normal working position.
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FC 90
N Tighten down the wingnut
241BA003 KN
350BA022 KN
241BA004 KN
90°
241BA005 KN
1
clockwise.
N Standing in the normal working
position, check the depth of cut
again and correct it if necessary,
Do not adjust the deflector.
The deflector has been set at the factory
so that the arrow on the deflector and
the open side point away from the
operator. This ensures that cuttings and
other debris are directed away from the
machine and operator.
English
Lawn edging
N Use the gunning sight (1) to line up
the blade on the edge.
N Starting the Engine
N Start the cut at no less than half
throttle and continue cutting at full
throttle.
N Hold and guide your edger so that
the blade is vertical.
N Cut steadily so that the engine is not
lugged down – do not apply force.
N Cut at no more than a normal
walking pace.
N Do not push the blade into the
ground.
N Always walk forwards when cutting,
do not pull the unit towards you.
N Edge at a steady pace to avoid
having to make several passes.
FC 90
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English
3
355BA030 KN
1
2
A
343BA023 KN
5
4
50 mm
( 2" )
002BA163 KN
2
1
002BA161 KN
Mounting the Loop Handle
Mounting the Loop Handle
N Position the loop handle (1) on the
drive tube, about 8 in (20 cm) (A)
forward of the control handle (2).
N Place the clamp (3) against the
drive tube and push it into the loop
handle.
N Fit the square nut (4) in the loop
handle, insert the clamp screw (5)
from the other side and tighten it
down firmly.
Adjusting the loop handle
N Line up the loop handle and move it
to the most comfortable position.
N Loosen the screw (5).
N Move the loop handle along the
drive tube as required – tighten
down the screw firmly.
Adjusting the Throttle
Cable
A properly adjusted throttle cable is the
precondition for correct operation in the
full throttle, starting throttle and idle
positions.
N Adjust the throttle cable only when
the unit is completely and properly
assembled.
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.
FC 90
14
English
241BA006 KN
1
6
3
2
4
5
241BA011 KN
6
10
8
9
241BA012 KN
7
4
7
Mounting the Cutting Blade
N Lay the power edger on its back so
that the blade mounting (1) faces
up.
forth together with the thrust
washer (4) until the pin slips into
position and blocks the shaft.
N Fit the combination wrench (5) on
the nut (6).
N Loosen and unscrew the nut
clockwise (left-hand thread).
N Remove the thrust washer.
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.
N Insert the stop pin (2) or screwdriver
– see "Special Accessories" – into
the hole (3) as far as stop – apply
slight pressure and turn back and
FC 90
N Place the blade (7) on the thrust
plate (8).
Collar (see arrow) must engage
the blade's mounting hole.
N Fit the thrust washer (4) on the
shaft (9) and block the shaft.
N Screw the mounting nut (6) on to the
shaft counterclockwise and tighten
it down firmly.
If the cup spring (10) on the
nut (6) has lost its tension, fit a
new nut.
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English
Fuel
This engine is certified to operate on
unleaded gasoline and the STIHL twostroke engine oil at a mix ratio of 50:1.
Your engine requires a mixture of highquality gasoline and quality two-stroke
air cooled engine oil.
Use mid-grade unleaded gasoline with a
minimum octane rating of 89 (R+M/2). If
the octane rating of the mid-grade
gasoline in your area is lower, use
premium unleaded fuel.
Fuel with a lower octane rating may
increase engine temperatures. This, in
turn, increases the risk of piston seizure
and damage to the engine.
The chemical composition of the fuel is
also important. Some fuel additives not
only detrimentally affect elastomers
(carburetor diaphragms, oil seals, fuel
lines, etc.), but magnesium castings and
catalytic converters as well. This could
cause running problems or even
damage the engine. For this reason
STIHL recommends that you use only
high-quality unleaded gasoline!
Gasoline with an ethanol content of
more than 10% can cause running
problems and major damage in engines
with a manually adjustable carburetor
and should not be used in such engines.
Engines equipped with M-Tronic can be
run on gasoline with an ethanol content
of up to 25% (E25).
Use only STIHL two-stroke engine oil or
equivalent high-quality two-stroke
engine oils that are designed for use
only in air cooled two-cycle engines.
We recommend STIHL HP Ultra 2-Cycle
Engine Oil since it is specially
formulated for use in STIHL engines.
Do not use BIA or TCW rated (twostroke water cooled) mix oils or other
mix oils that state they are for use in both
water cooled and air cooled engines
(e.g., outboard motors, snowmobiles,
chain saws, mopeds, etc.).
Take care when handling gasoline.
Avoid direct contact with the skin and
avoid inhaling fuel vapor. When filling at
the pump, first remove the canister from
your vehicle and place the canister on
the ground before filling. Do not fill fuel
canisters that are sitting in or on a
vehicle.
The canister should be kept tightly
closed in order to avoid any moisture
getting into the mixture.
The machine‘s fuel tank and the canister
in which fuel mix is stored should be
cleaned as necessary.
Fuel mix ages
Only mix sufficient fuel for a few days
work, not to exceed 3 months of storage.
Store in approved fuel-canisters only.
When mixing, pour oil into the canister
first, and then add gasoline. Close the
canister and shake it vigorously by hand
to ensure proper mixing of the oil with
the fuel.
Gasoline
US gal. US fl.oz
12.6
2 1/2 6.4
5 12.8
Dispose of empty mixing-oil canisters
only at authorized disposal locations.
Oil (STIHL 50:1 or equivalent high-quality oils)
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FC 90
English
002BA420 KN
002BA418 KN
002BA419 KN
249BA053 KN
249BA054 KN
249BA055 KN
249BA056 KN
Fueling
Preparations
N Before fueling, clean the filler cap
and the area around it so that dirt
cannot fall into the tank.
N Always position the machine so that
the filler cap is facing upwards.
One of two different filler caps is
installed as standard at the factory.
Threaded filler cap
Opening the toolless filler cap
N Swing the grip into an upright
position.
Refueling
Take care not to spill fuel while fueling,
and do not overfill the tank. STIHL
recommends use of the STIHL filling
system (special accessory).
Closing the toolless filler cap
N Position the cap with the grip in an
upright position; the raised
positioning marks must line up.
N Turn cap clockwise as far as it will
go (approx. 1/4 turn).
Toolless filler cap (with folding grip)
FC 90
N Turn the cap counterclockwise
(approx. 1/4 turn).
N Remove the filler cap.
N Fold the grip down so that it is flush
with the surface.
If the grip is not flush with the surface
and the lug on the clip does not engage
entirely in the recess (arrow), the cap is
not properly closed and the steps
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English
200BA421 KN
200BA422 KN
3
STOP
2
5
6
4
7
002BA181 KN
START
STOP-
1
described above must be repeated. See
also the "Toolless cap with grip" section
in the Safety Precautions.
Opening the threaded filler cap
N Turn the cap counterclockwise until
it can be removed from the tank
opening.
N Remove the filler cap.
Refueling
Take care not to spill fuel while fueling
and do not overfill the tank. STIHL
recommends use of the STIHL filling
system (special accessory).
Closing the threaded filler cap
N Position cap.
N Turn the cap clockwise as far as it
will go and tighten it as securely as
possible by hand.
Starting / Stopping the
Engine
Control handle
Controls
1 Throttle trigger lockout
2 Throttle trigger
3 Slide control
Positions of slide control
4STOP-0 – engine off – the ignition is
switched off
5 F – normal run position – the engine
is running or can start
6 START – the ignition is switched on
– the engine can start
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FC 90
English
249BA057 KN
9
8
552BA014 KN
552BA015 KN
552BA016 KN
Symbol on slide control
7 h – stop symbol and arrow. To stop
the engine, push the slide control in
the direction of the arrow on the stop
symbol (h) to STOP-0.
Starting
N Press down the trigger lockout lever
and squeeze the throttle trigger.
N and hold them in that position.
N Move the slide control to START
and hold it there.
N Now release the throttle trigger,
slide control and trigger lockout in
that order. This is the starting
throttle position.
N Set the choke knob (8)
g if the engine is cold
e for warm start – also use this posi-
tion if the engine has been running
but is still cold.
N Press the fuel pump bulb (9) at least
five times – even if the bulb is
already filled with fuel.
Starting
N Place the unit on the ground: It must
rest securely on the engine support
and the deflector. Check that the
blade is not touching the ground or
any other obstacles.
N Make sure you have a safe and
secure footing.
N Hold the unit with your left hand and
press it down firmly – your thumb
should be under the fan housing.
Do not stand or kneel on the drive
tube.
N Hold the starter grip with your right
hand.
N Pull the starter grip slowly until you
feel it engage and then give it a brisk
strong pull.
Do not pull out the starter rope all
the way – it might otherwise
break.
N Do not let the starter grip snap back.
Guide it slowly back into the housing
so that the starter rope can rewind
properly.
N Crank the engine until it begins to
fire. After no more than five
attempts, turn the choke knob to
e.
N Continue cranking.
As soon as the engine runs
N Blip the throttle trigger. The slide
control moves to the normal run
position F – and the engine settles
down to idle speed.
Make sure the carburetor is
correctly adjusted. The cutting
blade must not rotate when the
engine is idling.
Your machine is now ready for
operation.
FC 90
19
English
Stopping the engine
N Push the slide control in the
direction of the arrow on the stop
symbol (h) to STOP-0.
At very low outside temperatures:
As soon as the engine runs:
N Blip the throttle trigger to disengage
the starting throttle position. The
slide control moves to the normal
run position (F) – and the engine
settles down to idle speed.
N Open the throttle slightly.
N Warm up the engine for a short
period.
If the engine does not start
Choke knob
If you did not turn the choke knob to e
quickly enough after the engine began to
fire, the combustion chamber is flooded.
N Turn the choke knob to e.
N Set the slide control, lockout lever
and throttle trigger to the starting
throttle position.
N Start the engine by pulling the
starter rope briskly – 10 to 20 pulls
may be necessary.
If the engine still does not start
N Move the slide control to STOP-0.
N Remove the spark plug – see
"Spark Plug".
N Dry the spark plug.
N Crank the engine several times with
the starter to clear the combustion
chamber.
N Refit the spark plug – see "Spark
Plug".
N Move the slide control to START.
N Set the choke knob to e – even if
the engine is cold.
N Now start the engine.
Throttle cable adjustment
N Check adjustment of throttle cable –
see chapter on "Adjusting the
Throttle Cable".
Fuel tank run until completely dry
N After refueling, press the fuel pump
bulb at least five times – even if the
bulb is filled with fuel.
N Set the choke knob according to
engine temperature.
N Start the engine.
Operating Instructions
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 frictional resistances in the
engine are greater during this period.
The engine develops its maximum
power after about 5 to 15 tank fillings.
During Operation
After a long period of full throttle
operation, allow the engine to run for a
short while at idle speed so that engine
heat can be dissipated by the flow of
cooling air. This protects enginemounted components (ignition,
carburetor) from thermal overload.
After Finishing Work
Storing for a short period: Wait for the
engine to cool down. Empty the fuel tank
and keep the machine in a dry place,
well away from sources of ignition, until
you need it again. For longer out-ofservice perionds – see "Storing the
Machine".
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FC 90
English
1
273BA006 KN
2
4
Cleaning the Air Filter
If there is a noticeable loss of engine
power
N Turn the choke knob to g
N Take out the screw (1) and remove
the filter cover (2).
N Clean away loose dirt from around
the filter.
N Grip the filter element (3) at the
cutout (arrow) in the filter
housing (4) and remove it.
N Fit a new filter element. As a
temporary measure you can knock it
out on the palm of your hand or blow
it out with compressed air. Do not
wash.
N Replace damaged parts.
Engine Management Adjusting the Carburetor
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 comes from the factory
with a standard setting.
This setting provides an optimum fuel-air
mixture under most operating
conditions.
With this carburetor it is only possible to
adjust the high speed and low speed
screws within fine limits.
Standard Setting
N Shut off the engine.
N Mount the cutting blade.
N Check the air filter and clean or
replace as necessary.
N Check that the throttle cable is
properly adjusted – readjust if
necessary – see chapter on
"Adjusting the Throttle Cable".
N Check the spark arresting screen
and clean or replace as necessary.
Installing the filter
N Install the filter element in the filter
housing and fit the cover.
N Insert the screw and tighten it down
firmly.
FC 90
21
English
249BA051 KN
N Carefully turn both adjusting screws
counterclockwise as far as stop:
– The high speed screw (H) is 3/4 turn
open.
– The low speed screw (L) is 3/4 turn
open.
N Start and warm up the engine.
N Adjust idle speed with the idle speed
screw (LA) so that the cutting blade
does not rotate.
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 or at sea level.
Rule of thumb:
Turn the high speed screw (H) about
one quarter of a turn for every 3300 ft
(1000 m) change in altitude.
Conditions for adjustment
N Carry out the standard setting
without disturbing the high speed
screw (H).
N Warm up the engine 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.
Readjust idle
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 for about 3
minutes.
Engine stops while idling
N Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly – the cutting blade
must not rotate.
Blade rotates when engine is idling
N Turn the idle speed screw (LA)
counterclockwise until the cutting
blade stops rotating and then turn
the screw about another 1/2 to 3/4
turn in the same direction.
If the cutting blade continues to
rotate 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 Turn the low speed screw (L)
counterclockwise, no further than
stop, until the engine runs and
accelerates smoothly.
Erratic idling behavior
Idle setting is too rich
N Turn the low speed screw (L)
clockwise, no further than stop, until
the engine runs and accelerates
smoothly.
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FC 90
English
249BA059 KN
1
2
3
2
249BA060 KN
1
249BA063 KN
Spark Arresting Screen in
Muffler
In some countries the muffler is
equipped with a spark arresting screen.
N If the engine is down on power,
check the spark arresting screen in
the muffler.
N Wait for the muffler to cool down.
N Move the slide control to STOP-0.
N Take out the screw (1).
N Take out the screw (4).
N Lift the spark arresting screen (5)
and pull it out.
N Clean the spark arresting screen. If
the screen is damaged or heavily
carbonized, fit a new one.
N Refit the spark arresting screen.
N Insert the screw and tighten it down
firmly.
N Fit the shroud.
Spark Plug
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 eroded.
Wrong fuel mix (too much engine oil in
the gasoline), a dirty air filter and
unfavorable running conditions (mostly
at part throttle etc.) affect the condition
of the spark plug. These factors cause
deposits to form on the insulator nose
which may result in trouble in operation.
Removing the spark plug
N Move the slide control to STOP-0.
N Take out the screws (2) and remove
the shroud (3).
FC 90
N Pull off the spark plug boot (1).
N Unscrew the spark plug.
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English
000BA039 KN
A
2
1
002BA363 KN
1
241BA018 KN
2
Checking the Spark Plug
N Clean dirty spark plug.
N Check electrode gap (A) and
readjust if necessary – see
"Specifications".
N Use only resistor type spark plugs of
the approved range.
Rectify problems which have caused
fouling of spark plug:
– Too much oil in fuel mix.
– Dirty air filter.
– Unfavorable running conditions,
e.g. operating at part load.
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
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
N Screw home the spark plug, fit the
boot and press it down firmly.
Lubricating the Gearbox
Check grease level regularly, about
every 25 hours of operation.
N Unscrew the filler plug (1). If no
grease can be seen on the inside of
the filler plug, screw the tube (2) of
STIHL gear lubricant for
brushcutters – see "Special
Accessories" – into the filler hole.
N Squeeze up to 0.2 oz (5 g) grease
into the gearbox.
Do not completely fill the gearbox
with grease.
N Refit the filler plug and tighten it
down firmly.
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FC 90
Replacing the Starter Rope
1
1
249BA061 KN
2
1
4
3
5
249BA013 KN
249BA014 KN
6
249BA015 KN
and Rewind Spring
Replacing the Starter Rope
English
N Push the slide control in direction of
arrow h – to STOP-0.
N Take out the screws (1).
N Remove the starter cover (2) from
the housing.
FC 90
N Ease the spring clip (3) off the
starter post.
N Remove the rope rotor with
washer (4) and pawl (5).
N Remove the remaining rope from
the rotor and starter grip.
N Tie a simple overhand knot in the
new rope and then thread it through
the top of the grip and the rope
bushing (6).
N Thread the rope through the rotor
and secure it with a simple
overhand knot.
N Coat the rope rotor bearing bore
with non-resinous oil.
N Slip the rotor over the starter post –
turn it back and forth to engage the
anchor loop of the rewind spring.
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