STIHL FS 45 Instruction Manual
STIHL FS 45, 46
Instruction Manual
Manual de instrucciones
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.
Contents
English / USA
Guide to Using this Manual .............. 2
Safety Precautions and
Working Techniques ......................... 3
Approved Combinations of
Cutting Tool, Deflector,
Handle and Harness ....................... 16
Mounting the Loop Handle ............. 17
BA_SE_011_005_01_12.fmPrinted on chlorine-free paper.
Mounting the Deflector ................... 18
Mounting Cutting Tools ................... 18
Fuel ................................................ 21
Fueling ............................................ 22
Starting / Stopping the Engine ........ 23
Operating Instructions .................... 26
Cleaning the Air Filter ..................... 26
Motor Management ........................ 27
Adjusting the Carburetor ................ 27
Catalytic Converter ......................... 29
Checking the Spark Plug ................ 29
Inspections and Maintenance by
STIHL Service ................................ 30
Rewind Starter ................................ 30
Storing the Machine ........................ 31
Replacing the Nylon Line ............... 31
Replacing the Nylon Line ............... 33
Maintenance Chart ......................... 35
Parts and Controls .......................... 36
Printing inks contain vegetable oils; paper can be recycled.
Specifications ................................. 38
Special Accessories ....................... 39
Maintenance and Repairs ............... 39
STIHL Incorporated
Federal Emission
Control Warranty Statement ........... 40
STIHL Incorporated
California Exhaust and
Evaporative Emissions Control
Warranty Statement ........................ 42
Trademarks .................................... 44
Allow only persons who understand this
manual to operate your trimmer.
To receive maximum performance and
satisfaction from your STIHL trimmer, it
is important that you read and understand the maintenance and safety
precautions, starting on page 3, before
using your trimmer.
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 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.
STIHL's philosophy is to continually
improve all of its products. As a result,
engineering changes and improvements are made from time to time. If the
operating characteristics or the appearance of your trimmer differs from those
described in this manual, please contact
your STIHL dealer for information and
assistance.
STIHl
© ANDREAS STIHL AG & Co. KG, 2008
0458 232 8621 C. M7.2. E8. HFP.
1FS 45, FS 46
English / USA
Guide to Using this Manual
Pictograms
All the pictograms attached to the
machine are shown and explained in
this manual.
The operating and handling instructions
are supported by illustrations.
Symbols in text
The individual steps or procedures
described in the manual may be marked
in different ways:
: A bullet marks a step or procedure
without direct reference to an
illustration.
A description of a step or procedure that
refers directly to an illustration may
contain item numbers that appear in the
illustration.
Example:
Loosen the screw (1)
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 described below:
Warning where there is a risk of an
accident or personal injury or
serious damage to property.
Caution where there is a risk of
damaging the machine or its
individual components.
Note or hint which is not essential
for using the machine, but may
improve the operator’s understanding of the situation and result
in better use of the machine.
Note or hint on correct procedure in
order to avoid damage to the
environment.
Equipment and features
This instruction manual may refer to
several models with different
features. Components that are not
installed on all models and related
applications are marked with an
asterisk (*). Such components may
be available as special accessories
from your STIHL dealer.
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. If the
operating characteristics or the
appearance of your machine differ from
those described in this manual, please
contact your STIHL dealer for
assistance.
Therefore some changes, modifications
and improvements may not be covered
in this manual.
2
FS 45, FS 46
Safety Precautions and
Working Techniques
English / USA
Because a trimmer 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.
The terminology utilized in this manual
when referring to the power tool reflects
the type of cutting attachments that 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). 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. 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 this trimmer.
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.
Thrown objects, including broken heads
or polymer blades, may result in serious
or fatal injury to the operator or
bystanders.
Use your trimmer equipped with the
appropriate cutting attachment only for
cutting grass and similar material. It
must not be used for any other
purposes, since such misuse may result
in an accident or 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.
3FS 45, FS 46
English / USA
!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. 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 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.
Keep the AV system well maintained. A
power tool with loose components or
with damaged or worn AV buffers will
tend to have higher vibration levels.
Maintain a firm grip at all times, but do
not squeeze the handles with constant,
excessive pressure. Wear gloves and
keep your hands warm. 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.
4
FS 45, FS 46
English / USA
!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.
!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 protective
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.
!Warning!
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,
blade and the cutting
attachment. 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.
5FS 45, FS 46
English / USA
THE POWER TOOL
For illustrations and definitions of the
power tool parts see the chapter on
“Main Parts and Controls.”
!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 “Power Tools and 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 line 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 the cutting attachment has stopped
before putting a trimmer 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. For further
instructions see the safety precautions
and the chapter on “Fuel” of the
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 serious
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
389BA019 KN
fuel or the power tool. Note that
combustible fuel vapor may escape from
the fuel system.
6
FS 45, FS 46
English / USA
Fueling Instructions
!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, 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.
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
triangular marks on the grip of the cap
and on the fuel tank opening lining up.
Using the grip, turn the cap firmly
clockwise as far as it will go (approx. a
quarter turn).
Fold the grip flush with the
top of the cap. 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 neck,
the cap is not properly seated and
tightened and you must repeat the
above steps.
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.
Before Starting
!Warning!
Always check your power tool for proper
condition and operation before starting,
particularly the throttle trigger, throttle
trigger interlock, stop switch, cutting
attachment and deflector. 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 head to fly off and
seriously injure the operator or
bystanders.
7FS 45, FS 46
English / USA
!Warning!
The cutting attachment must be properly
tightened and in safe operating
condition. Inspect for loose parts (nuts,
screws, etc.). Replace damaged heads
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, 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").
Keep the deflector (and the attached
skirt where appropriate) adjusted
properly at all times (see chapters on
"Mounting the Deflector" and "Mounting
the Cutting Attachments" of your
instruction manual).
Arrows on the deflector (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 the hand grip and harness (if you
are wearing one) 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.
Starting
Start the engine at least 10 feet
(3 meters) from the fueling spot,
outdoors only.
Start and operate your power tool
without assistance. 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.
!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.
8
FS 45, FS 46
English / USA
With the engine running only at idle,
attach the power tool to the spring hook
of your harness if you are using one (see
appropriate chapter of the instruction
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
002BA054 KN
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
or grease.
9FS 45, FS 46
English / USA
!Warning!
Never attempt to operate
your power tool with one
hand. Loss of control of
the power tool resulting in
personal 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.
10
FS 45, FS 46
English / USA
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.
15m (50ft)
15m (50ft)
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 is normally to be used at
ground level with the cutting attachment
parallel to the ground. Use of a trimmer
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.
!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 head for cracks, wear
and damage.
!Warning!
A loose head may vibrate, crack, break
or come off the trimmer, 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 head loosens after
being properly tightened, stop work
immediately. The retaining nut may be
worn or damaged and should be
replaced. If the head continues to
loosen, see your STIHL dealer. Never
use a trimmer 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!
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.
11FS 45, FS 46
English / USA
!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
catalytic 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.
12
FS 45, FS 46
English / USA
USING THE CUTTING
ATTACHMENTS
For an illustration of the various cutting
attachments and instructions on proper
mounting see the chapter on "Mounting
the Cutting Attachments" in your
instruction manual.
!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 this trimmer.
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 equipped with a line-limiting
blade in the deflector in order to keep the
line at the proper length (see "Parts and
Controls" 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 AutoCut mowing head
Nylon cutting cord advances
automatically when tapped against the
ground (TapAction)
000BA019 KN
STIHL PolyCut mowing head
For mowing unobstructed edges of
meadows (without posts, fences, trees
or similar obstacles). Uses either nylon
lines or nonrigid, pivoting polymer
blades.
!Warning!
Three 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.
13FS 45, FS 46
English / USA
1
2
Do not continue using the PolyCut if one
of the circular holes (1; arrow) becomes
visible or if the projecting rim (2; arrow)
has worn away. Install a new mowing
head.
!Warning!
If the wear limit marks are ignored, there
is a risk of the cutting attachment
shattering and flying parts injuring the
operator or bystanders. To reduce the
risk of accidents from shattered blades,
avoid contact with stones, metal and
similar solid objects. Check PolyCut
blades for cracks at regular intervals. If a
crack is found on one blade, always
replace all blades.
STIHL FixCut mowing head
Uses pre-cut lengths of nylon line.
Observe wear indicators.
002BA073 KN
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
002BA074 KN
may otherwise shatter and flying objects
could result in injury to the operator or
bystanders. Install a new mowing head.
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.
Please refer to the maintenance charts
respectively the maintenance notes in
this 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.
14
FS 45, FS 46
English / USA
!Warning!
Use the specified spark plug, and make
sure it and the ignition lead are always
clean and in good condition. Always
press spark plug boot snugly onto spark
plug terminal of the proper size. (Note: If
terminal has 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 attempt to repair damaged or
broken heads. 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.
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.
15FS 45, FS 46
English / USA
002BA000 KN
0
Approved Combinations of Cutting Tool, Deflector, Handle
and Harness
Cutting Tools
1 STIHL AutoCut C 5-2 mowing head
2 STIHL AutoCut 5-2 mowing head
3 STIHL PolyCut 6-3 mowing head
4 STIHL FixCut 5-2 mowing head
Deflector
5 Deflector with line limiting blade for
mowing heads only (see “Mounting
the Deflector”)
Handle
6 Loop handle
Equipment
The complete trimmer includes:
– Cutting tool
– Deflector
– Handle
– Shoulder strap (special accessory)
Select the correct combination from
the table according to the cutting tool
you intend to use. Read the table
horizontally from left to right.
Warning!
To reduce the risk of injury from
thrown objects or blade contact,
never operate your unit without the
proper deflector for the cutting
attachment being used. To reduce
the risk of injury from loss of control
and / or contact with the cutting tool,
make sure your unit is equipped with
a proper handle for the type of cutting
attachment being used.
Warning!
Only mowing heads (1, 2, 3, 4) may be
used on loop-handled trimmers with
a curved drive tube.
To reduce the risk of accidents and
Harness/Shoulder Strap
7 Shoulder strap may be used
injury, avoid contact with the rotating
cutting tool.
Cutting Tools Deflector Handle Shoulder Strap
1
Schnur/LINE 2
Schnur/LINE 1
681FK213 KN
2
5
3
681FK028 KN
6
7
02BA125 KN
4
16
FS 45, FS 46
Mounting the Loop Handle
223BA017 KN
6
English / USA
Adjusting loop handle to most
comfortable position
A
1
: Loosen the wingnut (6).
: Slide or rotate the loop handle (1) on
the drive tube as required.
: Tighten the wingnut (6).
2
5
3
4
223BA018 KN
: Place friction liner in the loop handle : Fit the loop handle (1) on the drive
tube, approx. 20 cm (8 in) (A)
forward of the control handle (2).
: Push the spacer (3) (not all markets)
into the loop handle until it fits
snugly.
: Insert the screw (4) through the loop
handle and the spacer so that the
screw head locates in the hexagon
recess.
: Fit the washer (5) and wingnut (6)
and tighten down firmly.
232BA069 KN
17FS 45, FS 46
English / USA
Mounting the Deflector
2
1
4
3
: Push the deflector (1) over the
clamp (2).
: Insert nut (3) in the hex recess in the
deflector.
: Make sure the holes line up.
: Fit screw (4) and tighten it down
firmly.
Mounting Cutting Tools
232BA066 KN
232BA067 KN
Preparations
: Lay your trimmer on its back with
the loop handle and shroud pointing
down and the output shaft facing up.
1
3
2
4
232BA026 KN
Thrust Plate
The thrust plate is shipped with the
Polycut 6-3 and FixCut 5-2. It is only
required for these mowing heads.
AutoCut 5-2 mowing head
AutoCut C 5-2 mowing head
: Pull the thrust plate (1) (if fitted) off
the shaft (2).
232BA033 KN
18
STIHL PolyCut 6-3 mowing head,
STIHL FixCut 5-2 mowing head
: Slip the thrust plate (1) over the
shaft (2) and engage hexagon
recess (3) on external hexagon (4).
FS 45, FS 46
English / USA
8
4
2
3
1
3
Mounting the Mowing Head
Keep instruction sheet for mowing
head in a safe place.
Assembling STIHL AutoCut 5-2
: Fit the spring (1) in the head (2).
All other steps are described in the
instruction sheet provided.
: Wind the nylon lines (3) onto the
spool (4).
: Thread the ends of the nylon lines
through the sleeves and place the
spool in the head.
2
7
5
6
232BA054 KN
STIHL AutoCut 5-2
: Push the mowing head (2) over the
shaft (5) and engage the hex recess
(7) on the external hexagon (6).
: Place the cap (8) on the head –
turn it clockwise as far as stop and
then tighten it down firmly.
8
Schnur/LINE 2
2
Schnur/LINE 1
9
232BA053 KN
STIHL AutoCut C 5-2
: Push the mowing head (2) over the
shaft – as with the AutoCut 5-2.
: Screw the spool (9) into the head
until the two arrow points are in
alignment (see illustration) – secure
the spool in this position.
: Push the cap (8) into the spool as
far as stop, turning it clockwise at
the same time.
: Turn cap as far as stop and tighten
it down by hand.
681BA018 KN
19FS 45, FS 46
English / USA
10
11
5
STIHL Polycut 6-3
: Fit the thrust plate on the shaft.
: Insert mounting nut (10) in the
mowing head.
: Screw mowing head (11) clockwise
onto the shaft (5) as far as stop.
: Block the output shaft with the stop
pin.
: Tighten down the mowing head.
Remove the tool used to block the
shaft.
681BA019 KN
Blocking the shaft
: Block the shaft by pushing the stop
pin (12) through the holes (13) in the
deflector and thrust plate – turn the
thrust plate back and forth if
necessary.
: Tighten down the mowing head
firmly.
Remove the tool used to block the
shaft.
5
4
3
1
2
232BA074 KN
STIHL FixCut 5-2
: Fit the thrust plate (2) on the shaft.
: Place the mowing head on the
thrust plate (2).
Collar (arrow) must locate in the
mowing head’s mounting hole.
: Push the thrust washer (3) over the
shaft (1) so that it locates against
the base.
: Block the output shaft.
: Use the combination wrench (5) to
screw the mounting nut (4)
counterclockwise onto the output
shaft and it tighten down firmly.
Remove the tool used to block the
shaft.
20
FS 45, FS 46
Fuel
English / USA
2
1
Adjusting Nylon Line
STIHK AutoCut
: old the rotating cutting head
horizontal to the ground – tap it on
the ground – about 1 1/4" (3 cm)
fresh line is advanced.
: The blade (1) on the deflector (2)
trims surplus line to the correct
length. Avoid tapping the head more
than once.
Line feed operates only if both lines
still have a minimum length of 1"
(2.5 cm).
Removing the Mowing Head
STIHL AutoCut
: Hold the mowing head steady
and unscrew the cap
counterclockwise.
STIHL PolyCut
: Block the shaft.
: Unscrew the mowing head
counterclockwise.
STIHL FixCut
: Block the shaft.
: Use the combination wrench to
232BA007 KN
loosen and unscrew the mounting
nut clockwise from the output shaft.
If the mounting nut is too loose, fit a
new one.
Replacing Nylon Line / Cutting
Blades
STIHL AutoCut
See chapter on "Replacing Nylon Line".
STIHL PolyCut, FixCut
Refer to instructions supplied with the
mowing head.
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
nationally recognized high-quality
unleaded gasoline!
21FS 45, FS 46
English / USA
Fueling
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 50:1 two-stroke
engine oil since it is specially formulated
for use in STlHL 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,
chainsaws, 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
Oil (STIHL 50:1 or
equivalent high-quality oils)
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.
232BA046 KN
Before fueling, clean the filler cap and
the area around it to ensure that no dirt
falls into the tank.
Always thoroughly shake the mixture in
the canister before fueling your
machine.
In order to reduce the risk of burns
or other personal injury from
escaping gas vapor and fumes,
remove the fuel filler cap carefully
so as to allow any pressure build-up
in the tank to release slowly.
After fueling, tighten fuel cap as
securely as possible by hand.
22
FS 45, FS 46
Starting / Stopping
the Engine
2
1
3
6
7
English / USA
9
4
8
6
5
Controls
Stop switch (1) with positions:
I - normal run position (2) and
O - stop (3).
Throttle trigger interlock (4).
Throttle trigger (5) with tongue (6) and
catch (7).
232BA064 KN
Starting
: Move the stop switch to position I.
: Press down the throttle trigger
interlock and hold it there.
: Squeeze the throttle trigger until the
catch on the tongue (6) can be
engaged in the housing (arrow).
: Now release the throttle trigger,
tongue and throttle trigger interlock
in that order. This is the starting
throttle position.
232BA065 KN
: Set the choke lever (8):
For cold start to
For warm start to e
– also use this position if the engine
has been running but is still cold.
: Press fuel pump bulb (9) at least five
times even if bulb is filled with fuel.
g
232BA011 KN
23FS 45, FS 46
English / USA
: Put the unit on the ground: It must
rest securely on the engine support
and deflector.
Check that the cutting tool is not
touching the ground or any other
obstacles.
: Make sure you have a firm footing:
Hold the unit with your left hand and
press it down firmly – your thumb
should be under the housing.
Do not stand or kneel on the drive
tube!
232BA012 KN
232TI013 KN
Standard versions:
: Pull the starter grip slowly with your
right hand 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 break.
Versions with ErgoStart:
: Pull the starter grip slowly with your
right hand until you feel the first stop
– and then pull it out slowly and
steadily.
Do not pull out the starter rope to its
full length – it might break.
: Do not let the starter grip snap back.
Guide it slowly back into the housing
so that the starter rope can rewind
properly.
8
: Continue cranking until engine runs.
: After no more than 5 pulls, move the
232BA014 KN
choke lever e and continue
cranking.
As soon as the engine runs
: Squeeze throttle until the tongue
disengages – the engine will settle
down to idle speed.
Make sure the carburetor is
correctly adjusted – the cutting tool
must not rotate when the engine is
idling.
Your machine is now ready for
operation.
232TI015 KN
24
FS 45, FS 46
English / USA
To shut down the engine:
: Move the stop switch to O.
If the engine does not start
Choke lever
If you did not move the choke lever to e
quickly enough after the engine began to
fire, the combustion chamber has
flooded.
: Set the choke lever to e
: Move stop switch to I, interlock lever
and throttle trigger to starting throttle
position.
: Start the engine by pulling the
starter rope firmly. 10 to 20 pulls
may be necessary.
If the engine still does not start
10
: Unscrew and dry off the spark plug.
: Open the throttle wide.
: Crank the engine several times with
the starter to clear the combustion
chamber.
: Refit the spark plug.
: Connect the spark plug boot – push
it down firmly.
: Move the stop switch to I
: Set choke lever to e
– even if engine is cold.
: Now start the engine.
Fuel tank run until dry
: After refueling, press the fuel pump
bulb at least fives times even if the
bulb is filled with fuel.
: Set the choke lever according to
engine temperature.
: Now start the engine.
232BA048 KN
: Move stop switch to O.
: Pull off the spark plug boot (10).
25FS 45, FS 46
English / USA
Operating Instructions Cleaning the Air Filter
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 engine to run for a while
at idle speed so that the heat in the
engine can be dissipated by flow of
cooling air. This protects enginemounted components (ignition,
carburetor) from thermal overload.
After finishing work
Wait for engine to cool down. Drain the
fuel tank. Store the machine in a dry
place. Check tightness of nuts and
screws (not adjusting screws) at regular
intervals and retighten as necessary.
1
Dirty air filters reduce engine power
increase fuel consumption and make
starting more difficult.
If there is a noticeable loss of engine
power
: Set choke lever to g
: Press in the tab (1) and swing the
filter cover (2) open.
: Clean away loose dirt from around
the filter.
2
4
3
232BA017 KN
: Remove the felt filter element (3).
: Do not wash the felt element. Fit a
new one. As a temporary measure,
clean it by knocking it out on the
palm of your hand or blowing it out
with compressed air.
Replace damaged parts of filter.
: Place the felt element (3) in the filter
housing (4).
: Close the filter cover so that it snaps
into position.
232BA018 KN
26
FS 45, FS 46
Motor Management Adjusting the Carburetor
English / USA
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.
L
H
1
4/
3
LA
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 engine idle speed within fine
limits.
Standard Setting
: Shut off the engine.
: Mount the cutting tool.
: Check the air filter and replace if
necessary.
: Turn high speed screw (H)
counterclockwise (max.
far as stop.
: Carefully screw the low speed
screw (L) down onto its seat. Then
open it one turn counterclockwise
: Start and warm up the engine.
: Adjust idle speed with the idle speed
screw (LA) so that the cutting tool
does not rotate.
233BA028 KN
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.
3
/4 turn) as
27FS 45, FS 46
English / USA
Rule of thumb
Turn high speed screw (H) about
1/4 turn over for every 1000m
(3.300 ft) change in altitude.
Conditions for adjustment
Carry out adjustment with nylon line
mowing head, making sure the
cutting lines are at full length (as far
as limiter blade on deflector).
: Carry out standard setting without
changing the high speed screw (H).
: Warm up engine for about
3 minutes.
: Open the throttle wide.
At high altitudes
: Turn the high speed screw (H)
clockwise (leaner) no further than
stop until there is no noticeable
increase in engine speed.
At sea level
: Turn the high speed screw (H)
counterclockwise (richer) no further
than stop until there is no noticeable
increase in engine speed.
it is possible that maximum engine
speed will already be reached with
the standard setting in each case.
Adjusting Idle Speed
It is usually necessary to change the
setting of the idle speed screw (LA)
after every correction to the low speed
screw (L).
: Warm up engine.
Engine stops while idling
: Turn idle speed screw (LA) slowly
clockwise until the engine runs
smoothly – cutting tool must not
rotate.
Cutting tool rotates when engine is
idling
: Turn idle speed screw (LA) slowly
counterclockwise until cutting tool
stops rotating and then turn the
screw about another
1
/2 to 1 turn in
the same direction.
Erratic idling behavior, engine stops
even though setting of LA screw is
correct, poor acceleration
Idle setting too lean:
: Turn low speed screw (L)
counterclockwise (about 1/4 turn)
until the engine runs and
accelerates smoothly.
Erratic idling behavior
Idle setting too rich:
: Turn low speed screw (L) clockwise
(about
1
/4 turn) until the engine runs
and accelerates smoothly.
28
FS 45, FS 46
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