STIHL FS 38
WARNING
Read Instruction Manual thoroughly
before use and follow all safety
precautions – improper use can
cause serious or fatal injury.
ADVERTENCIA
Antes de usar la máquina 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 - 41
Manual de instrucciones
42 - 88
Contents
English
Guide to Using this Manual 2
Safety Precautions and Working
Techniques 3
Approved Combinations of Cutting
Attachment, Deflector, Handle and
Harness 15
Mounting the Loop Handle 16
Mounting the Deflector 17
Mounting the Cutting Attachment 17
Original Instruction ManualPrinted on chlorine-free paper
Fuel 19
Fueling 21
Starting / Stopping the Engine 22
Operating Instructions 25
Cleaning the Air Filter 25
Engine Management 26
Adjusting the Carburetor 26
Spark Plug 27
Engine Running Behavior 28
Storing the Machine 29
Maintaining the Mowing Head 29
Inspections and Maintenance by
Dealer 30
Printing inks contain vegetable oils, paper can be recycled.
Maintenance and Care 31
Main Parts 33
Specifications 34
Maintenance and Repairs 35
Disposal 35
Limited Warranty 36
STIHL Incorporated Federal
Emission Control Warranty
Statement 36
STIHL Incorporated California
Exhaust and Evaporative
Emissions Control Warranty
Statement 38
Trademarks 40
Allow only persons who fully understand
this manual to operate your trimmer.
To receive maximum performance and
satisfaction from your STIHL trimmer, it
is important that you read, understand
and follow the safety precautions and
the operating and maintenance
instructions in chapter "Safety
Precautions and Working Techniques"
before using your trimmer. For further
information you can go to
www.stihlusa.com.
Contact your STIHL dealer or the STIHL
distributor for your area if you do not
understand any of the instructions in this
manual.
WARNING
Because a trimmer is a high-speed
cutting tool some special safety
precautions must be observed to reduce
the risk of personal injury. Careless or
improper use may cause serious or even
fatal injury.
Make sure your unit is equipped with the
proper deflector, handle and harness for
the type of cutting attachment being
used. Always wear proper eye
protection.
© ANDREAS STIHL AG & Co. KG, 2022
0458-234-8621-D. VB4.D22.
0000006367_024_GB
FS 38
This instruction manual is protected by copyright. All rights reserved, especially the rights to reproduce, translate and process
with electronic systems.
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
Filler hole for gear
lubricant
Air intake summer mode
Air intake winter mode
Handle heating
Symbols in Text
Many operating and safety instructions
are supported by illustrations.
The individual steps or procedures
described in the manual may be shown
in different ways:
N A bullet indicates 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. For example:
N Remove the screw (1)
N Pull the spark arresting screen (2)
upwards out of the muffler
In addition to the operating instructions,
this manual may contain paragraphs
that require your special attention. Such
paragraphs are indicated with the
symbols and signal words described
below:
DANGER
Indicates a hazardous situation that, if
not avoided, will result in death or
serious injury.
WARNING
Indicates a hazardous situation that, if
not avoided, could result in death or
serious injury.
NOTICE
Indicates a risk of property damage,
including damage to the machine or its
individual components.
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 or the STIHL
distributor for your area for assistance.
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FS 38
English
Safety Precautions and
Working Techniques
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.
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
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.
FS 38
3
English
WARNING
Be alert – if you get tired, take a break.
Tiredness may result in loss of control.
Working with any power tool can be
strenuous. If you have any condition that
might be aggravated by strenuous work,
check with your doctor before operating
this machine.
WARNING
Prolonged use of a power tool (or other
machines) exposing the operator to
vibrations may produce whitefinger
disease (Raynaud's phenomenon) or
carpal tunnel syndrome.
These conditions reduce the hand's
ability to feel and regulate temperature,
produce numbness and burning
sensations and may cause nerve and
circulation damage and tissue necrosis.
All factors which contribute to
whitefinger disease are not known, but
cold weather, smoking and diseases or
physical conditions that affect blood
vessels and blood transport, as well as
high vibration levels and long periods of
exposure to vibration are mentioned as
factors in the development of whitefinger
disease. In order to reduce the risk of
whitefinger disease and carpal tunnel
syndrome, please note the following:
Most STIHL power tools are available
with an anti-vibration ("AV") system
designed to reduce the transmission of
vibrations created by the machine to the
operator's hands. An AV system is
recommended for those persons using
power tools on a regular or sustained
basis.
– Wear gloves and keep your hands
warm.
– Keep the AV system well
maintained. A power tool with loose
components or with damaged or
worn AV elements will tend to have
higher vibration levels.
– Maintain a firm grip at all times, but
do not squeeze the handles with
constant, excessive pressure. Take
frequent breaks.
All the above-mentioned precautions do
not guarantee that you will not sustain
whitefinger disease or carpal tunnel
syndrome. Therefore, continual and
regular users should closely monitor the
condition of their hands and fingers. If
any of the above symptoms appear,
seek medical advice immediately.
WARNING
The ignition system of the STIHL unit
produces an electromagnetic field of a
very low intensity. This field may
interfere with some pacemakers. To
reduce the risk of serious or fatal injury,
persons with a pacemaker should
consult their physician and the
pacemaker manufacturer before
operating this tool.
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 Z87 "+" (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.
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FS 38
English
234BA016 KN
Be particularly alert and cautious when
wearing hearing protection because
your ability to hear warnings (shouts,
alarms, etc.) is restricted.
Always wear heavy duty
work gloves (e.g. made of
leather or other wear
resistant material) when
handling the machine
and metal blades. Heavyduty, nonslip gloves
improve your grip and
help to protect your
hands.
Clothing must be sturdy
and snug-fitting, but allow
complete freedom of
movement. Wear long
pants made of heavy
material to help protect
your legs. Do not wear
shorts, sandals or go
barefoot.
Avoid loose-fitting jackets, scarfs, neckties,
jewelry, flared or cuffed
pants, unconfined long
hair or anything that
could become caught on
branches, brush or the
moving parts of the unit.
Secure hair so it is above
shoulder level.
Good footing is very
important. Wear sturdy
boots with nonslip soles.
Steel-toed safety boots
are recommended.
THE POWER TOOL
For illustrations and definitions of the
power tool parts see the chapter on
"Main Parts."
WARNING
Never modify this power tool in any way.
Only attachments supplied by STIHL
and expressly approved by STIHL for
use with the specific STIHL model are
authorized. Although certain
unauthorized attachments are useable
with STIHL power tools, their use may,
in fact, be extremely dangerous. For the
cutting attachments authorized by
STIHL for your unit, see the chapter
"Approved Combinations of Cutting
Attachment, Deflector, Handle and
Harness" in the instruction manual or the
STIHL "Cutting Attachments, Parts &
Accessories" catalog.
If this tool is subjected to unusually high
loads for which it was not designed (e.g.
heavy impact or a fall), always check
that it is in good condition before
continuing work. Check in particular that
the fuel system is tight (no leaks) and
that the controls and safety devices are
working properly. Do not continue
operating this machine if it is damaged.
In case of doubt, have it checked by your
STIHL servicing dealer.
THE USE OF THE POWER TOOL
Transporting the Power Tool
WARNING
To reduce the risk of injury from loss of
control and 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 oil-
gasoline mixture for fuel (see the "Fuel"
chapter in this instruction manual).
FS 38
5
English
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 fuel or the power
tool. Note that combustible fuel vapor may
escape from the fuel
system.
Fueling Instructions
WARNING
To reduce the risk of fire and serious
personal injury, always place the power
tool on the ground before attempting to
fuel the machine.
WARNING
Pick a Safe Location
To reduce the risk of fire and explosion,
fuel your power tool in a well-ventillated
area, outdoors away from flames, pilot
lights, heaters, electric motors, and
other sources of ignition. Vapors can be
ignited by a spark or flame many feet
away. 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 power tool. Take care not to get fuel
on your clothing. If this happens, change
your clothing immediately.
Allow the Power Tool to Cool Before
Removing the Fuel Cap
WARNING
Gasoline vapor pressure may build up
inside the fuel tank. The amount of
pressure depends on a number of
factors such as the fuel used, altitude
and temperature. To reduce the risk of
burns and other personal injury from
escaping gas, vapor and fumes, always
shut off the engine and allow it to cool
before removing the fuel cap.
The engine is air cooled. When it is shut
off, cooling air is no longer drawn across
the cylinder and engine temperatures
will rise for several minutes before
starting to cool. In hot environments,
cooling will take longer. To reduce the
risk of burns and other personal injury
from escaping gas, vapor and fumes,
allow the power tool to cool. If you need
to refuel before completing a job, turn off
the machine and allow the engine to cool
before opening the fuel tank.
Fuel Spraying or “Geysering”
WARNING
Removing the cap on a pressurized fuel
tank can result in gasoline, vapors and
fumes being forcefully sprayed out from
the fuel tank in all directions. The
escaping gasoline, vapors or fumes can
cause serious personal injury, including
fire and burn injury, or property damage.
Sometimes also referred to as "fuel
geysering," fuel spraying is an expulsion
of fuel, vapors and fumes which can
occur in hot conditions, or when the
engine is hot, and the tank is opened
without allowing the power tool to cool
adequately. It is more likely to occur
when the fuel tank is half full or more.
Pressure is caused by fuel and heat and
can occur even if the engine has not
been running. When gasoline in the fuel
tank is heated (by ambient
temperatures, heat from the engine, or
other sources), vapor pressure will
increase inside the fuel tank.
Some blends of gasoline, particularly
those designed for use in winter, are
more volatile and may cause tanks to
pressurize more quickly or create
greater pressure. At higher altitudes,
fuel tank pressurization is more likely.
How to Avoid Fuel Spraying
Removing the fuel cap on a pressurized
tank can result in gasoline, vapors and
fumes being forcefully sprayed out from
the fuel tank in all directions. To reduce
the risk of burns, serious injuries or
property damage from fuel spraying:
– Follow the fueling instructions in this
chapter.
– Always assume your fuel tank is
pressurized.
– Allow the power tool to cool before
removing the fuel cap.
6
FS 38
English
– In hot environments, cooling will
take longer.
– The engine is air cooled. When it is
shut off, cooling air is no longer
drawn across the cylinder and the
engine temperature will rise for
several minutes before starting to
cool.
After the power tool has cooled
appropriately, follow the safety
instructions in this chapter for removing
the cap.
Never remove the fuel filler cap by
turning it directly to the open position.
First check for residual pressure in the
tank by slowly turning the cap
approximately 1/2 turn counterclockwise. The cap should be held in
place by the threads while allowing
residual vapor/pressure to be relieved.
Once the fumes or vapor have been
relieved, turn the cap further until it can
be removed from the tank opening.
Use only good quality fuel that is
appropriate for the season (summer v.
winter blends). Some blends of
gasoline, particularly winter blends, are
more volatile and can contribute to fuel
spraying.
Removing the Threaded Fuel Filler Cap
WARNING
After allowing the power tool to cool,
remove the fuel filler cap slowly and
carefully to allow any remaining
pressure build-up in the tank to release:
– While maintaining steady,
downward pressure, slowly turn the
cap approximately 1/2 turn counterclockwise.
– If any significant venting occurs,
immediately re-seal the tank by
turning the cap clockwise to the
closed position. Allow the power
tool to cool further before
attempting to open the tank.
– Turn the cap to the open position
only after the contents of the tank
are no longer under pressure.
– Never remove the cap by turning it
directly to the open position. First
allow the power tool to cool
adequately and then release any
residual pressure by slowly turning it
approximately 1/2 turn counterclockwise.
– Never attempt to remove the cap
while the engine is still hot or
running.
Installing the Threaded Fuel Filler Cap
WARNING
Unit vibrations can cause
an improperly tightened
fuel filler cap to loosen or
come off and spill quantities of fuel. To reduce the
risk of fuel spillage and
fire, tighten the fuel filler
cap by hand with as
much force as possible.
Damaged or Broken Cap
If your fuel cap does not tighten properly,
it may be damaged or broken. Stop
using the power tool and take it to your
authorized STIHL dealer for repair.
Vapor Lock
WARNING
Vapor lock occurs when fuel in the fuel
line or carburetor vaporizes, causing
bubbles to block the free flow of liquid
fuel into the carburetor. Vapor lock
cannot be relieved or affected by
opening the fuel tank. Removing the fuel
filler cap without first allowing the power
tool to cool adequately can result in fuel
spraying. Always follow the instructions
in this section when removing the fuel
cap.
FS 38
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English
To relieve vapor lock:
– Press the manual fuel pump bulb at
least 20 to 30 times – even if the
bulb is already filled with fuel – to
clear the vapor and send liquid fuel
into the carburetor. Then start the
power tool. For specific starting
instructions, see the appropriate
section of your instruction manual.
– If the manual fuel pump bulb will not
be filled, place the Choke Lever to
the cold start position g and pull
the starter cord until the engine runs
or fires.
– If your power tool will not restart, or
if vapor lock occurs again, the
power tool is being used in
conditions too extreme for the fuel
being used. Discontinue use and let
the engine cool completely before
attempting to start the power tool.
Before Operation
WARNING
Always check your power tool for proper
condition and operation before starting,
particularly the throttle trigger, throttle
trigger lockout, stop switch, cutting
attachment, deflector and harness. The
throttle trigger must move freely and
always spring back to the idle position.
Never attempt to modify the controls or
safety devices.
WARNING
Check fuel system for leaks, especially
the visible parts, e.g., filler cap, hose
connections, manual fuel pump (only for
power tools equipped with a manual fuel
pump). Do not start the engine if there
are leaks or damage – risk of fire. Have
the power tool repaired by a STIHL
servicing dealer before using it.
WARNING
Never operate your power tool if it is
damaged, improperly adjusted or
maintained, or not completely and
securely assembled.
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
Do not mount any cutting attachment to
a unit without proper installation of all
required parts. Failure to use the proper
parts may cause the blade or head to fly
off and seriously injure the operator or
bystanders.
WARNING
The cutting attachment must be properly
tightened and not damaged. Inspect for
loose parts (nuts, screws, etc.) and for
cracked or damaged heads. 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, fuel mix,
grease or resin in order for you to
maintain a firm grip and properly control
your power tool.
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 Attachment" of your
instruction manual.)
Arrow on the deflector (as seen from the
underside) shows the correct direction of
rotation of the cutting attachment. When
viewed from above, however, the cutting
attachment rotates clockwise.
8
FS 38
English
002BA056 KN
Adjust carrying harness (if you are
wearing one) 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.
For specific starting instructions, see the
appropriate section of your instruction
manual.
Starting
Start the engine at least 10 feet (3 m)
from the fueling spot, outdoors only.
For specific starting instructions, see the
appropriate section of your manual.
Place the power tool on firm ground or
other solid surface in an open area.
Maintain good balance and secure
footing.
WARNING
To reduce the risk of injury from blade or
line contact, be absolutely sure that the
cutting attachment is clear of you and all
other obstructions and objects, including
the ground, because when the engine
starts at starting-throttle, engine speed
will be fast enough for the clutch to
engage and move the cutting
attachment.
Once the engine has started,
immediately blip the throttle trigger,
which should release the starting throttle
and allow the engine to slow down to
idle.
With the engine running only at idle,
attach the power tool to the spring hook
of your harness 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
Always hold the unit firmly with both
hands on the handles while you are
working. Wrap your fingers and thumbs
around the handles, keeping the
handles cradled between your thumb
and forefinger. Keep your hands in this
position to have your power tool under
control at all times. Make sure your
trimmer handles and grips are in good
condition and free of moisture, pitch, oil,
fuel mix or grease.
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.
FS 38
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15m (50ft)
WARNING
Never attempt to operate
your power tool with one
hand. Loss of control of
the power tool resulting in
serious or fatal injury may
result. To reduce the risk
of cut injuries, keep
hands and feet away
from the cutting attachment. Never touch a
moving cutting attachment with your hand or
any other part of your
body.
WARNING
Do not overreach. Keep proper footing
and balance at all times. Special care
must be taken in slippery conditions (wet
ground, snow) and in difficult, overgrown
terrain. Watch for hidden obstacles such
as tree stumps, roots and ditches to
avoid stumbling. For better footing, clear
away scrub and cuttings. Be extremely
cautious when working on slopes or
uneven ground.
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.
10
WARNING
As soon as the engine is
running, this product generates toxic exhaust
fumes containing chemicals, such as unburned
hydrocarbons (including
benzene) and carbon
monoxide, that are
known to cause respiratory problems, cancer,
birth defects, or other
reproductive harm. Some
of the gases (e.g. carbon
monoxide) may be colorless and odorless. To
reduce the risk of serious
or fatal injury / illness
from inhaling toxic fumes,
never run the machine
indoors or in poorly ventilated locations.
WARNING
If the vegetation being cut or the
surrounding ground is coated with a
chemical substance (such as an active
pesticide or herbicide), read and follow
the instructions and warnings that
accompanied the substance at issue.
WARNING
Inhalation of certain dusts, especially
organic dusts such as mold or pollen,
can cause susceptible persons to have
an allergic or asthmatic reaction.
Substantial or repeated inhalation of
dust and other airborne contaminants, in
particular those with a smaller particle
size, may cause respiratory or other
illnesses. Control dust at the source
where possible. Use good work
practices, such as operating the unit so
that the wind or operating process
directs any dust raised by the power tool
away from the operator. Follow the
recommendations of EPA / OSHA /
NIOSH and occupational and trade
associations with respect to dust
("particulate matter".) When the
inhalation of dust cannot be
substantially controlled, i.e., kept at or
near the ambient (background) level, the
operator and any bystanders should
wear a respirator approved by NIOSH /
MSHA for the type of dust encountered.
Operating Instructions
WARNING
Do not operate your power tool using the
starting throttle lock, as you do not have
control of the engine speed.
In the event of an emergency, shut off
the engine immediately – move the slide
control / stop switch to 0 or STOP.
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
FS 38
English
50 feet (15 m) away. To reduce the risk
of damage to property, also maintain this
distance from such objects as vehicles
or windows. Even maintaining a
minimum distance of 15 meters cannot
exclude the potential danger. Any
coworkers who must be in the restricted
area should also wear goggles or
protective glasses. Stop the engine
immediately if you are approached.
Never use metal
blades on this trimmer. Only mowing
heads are
authorized.
WARNING
Inspect the work area: To
reduce the risk of injury,
remove stones, pieces of
metal and other solid
objects which could be
thrown 15 meters or more
by the cutting attachment
or damage the cutting
attachment and property
(e.g. parked vehicles,
windows).
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
Some STIHL mowing heads have a
metal core. High-speed contact with
rock or other hard objects may create
sparks, which can ignite flammable
materials under certain circumstances.
Flammable materials include dry
vegetation and brush, particularly when
weather conditions are hot and dry.
When there is a risk of fire or wildfire, do
not use a mowing head with a metal core
around dry vegetation or brush. Contact
your local fire authorities or the U.S.
Forest Service if you have any question
about whether vegetation and weather
conditions are suitable for the use of a
mowing head with a metal core. STIHL
does not recommend using a mowing
head with a metal core when cutting in
rocky areas or in areas with debris or
other objects that could create sparks.
WARNING
If the head, blade or deflector becomes
clogged or stuck, always shut off the
engine and make sure the cutting
attachment has stopped before
cleaning. Grass, weeds, etc. should be
cleaned off the blade or from around the
head at regular intervals.
WARNING
To reduce the risk of unintentional
rotation of the cutting attachment and
injury, always shut off the engine and
remove the spark plug boot before
replacing the cutting attachment. To
reduce the risk of injury, always shut off
the engine before adjusting the length of
the nylon line on manually adjustable
mowing heads.
FS 38
11
English
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
Never modify your muffler. Any
modification could cause an increase in
heat radiation, sparks or sound level,
thereby increasing the risk of fire, burn
injury or hearing loss. You may also
permanently damage the engine. Have
your muffler serviced and repaired by
your STIHL servicing dealer only.
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. 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
An improperly mounted or damaged
cylinder housing or a
damaged/deformed muffler shell may
interfere with the cooling process of the
muffler. 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 muffler is furnished with a spark
arresting screen designed to reduce the
risk of fire from the emission of hot
particles. Never operate your unit with a
missing or damaged spark arresting
screen. If your gas/oil mix ratio is correct
(i.e., not too rich), this screen will
normally stay clean as a result of the
heat from the muffler 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. Some state or federal laws or
regulations may require a properly
maintained spark arrestor for certain
uses. See the "Maintenance, Repair and
Storing" section of these Safety
Precautions. Remember that the risk of
a brush or forest fire is greater in hot or
dry conditions.
WARNING
Some STIHL power tools
are equipped with a cata-
lytic converter, which is
designed to reduce the
exhaust emissions of the
engine by a chemical pro-
cess in the muffler. Due
to this process, the muf-
fler does not cool down
as rapidly as conven-
tional mufflers when the
engine returns to idle or
is shut off. To reduce the
risk of fire and burn inju-
ries when using a
catalytic converter,
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 com-
bustible materials while it
is still hot.
Using the Cutting Attachments
For an illustration of the various cutting
attachments and instructions on proper
mounting see the chapter on "Mounting
the Cutting Attachment" in your
instruction manual.
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.
12
FS 38
English
000BA019 KN
1
002BA073 KN
2
002BA074 KN
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 "Main
Parts" chapter in your instruction
manual.)
If the lawn edges are planted with trees
or bordered by a fence etc., it is best to
use a nylon line head. It achieves a
"softer" cut with less risk of damaging
tree bark etc. than polymer blades.
However, the polymer-bladed STIHL
PolyCut produces a better cut if there
are no plants along the edge of the lawn.
Sharpening is not necessary, and worn
polymer blades are easily replaced.
WARNING
To reduce the risk of serious injury,
never use wire or metal-reinforced line
or other material in place of the nylon
cutting lines. Pieces of wire could break
off and be thrown at high speed toward
the operator or bystanders.
STIHL AutoCut mowing head
Nylon cutting cord advances
automatically when tapped against the
ground (TapAction)
STIHL PolyCut mowing head 6-3
Uses nonrigid, pivoting polymer blades.
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.
FS 38
13
English
Do not continue using the mowing head
if the raised moldings (1) on the base
are missing or worn – see right
illustration above. The mowing head
may otherwise shatter and flying objects
could result in injury to the operator or
bystanders. Install a new mowing head.
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, 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.
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.
Your muffler is equipped with a sparkarresting screen to reduce the risk of
fire; never operate your power tool if the
screen is missing, damaged or clogged.
Remember that the risk of a brush or
forest fire is greater in hot or dry
weather.
In California, it is a violation of § 4442 or
§ 4443 of the Public Resources Code to
use or operate gasoline-powered tools
on forest-covered, brush-covered or
grass-covered land unless the engine’s
exhaust system is equipped with a
complying spark arrester that is
maintained in effective working order.
The owner/operator of this product is
responsible for properly maintaining the
spark arrester. Other states or
governmental entities/agencies, such as
the U.S. Forest Service, may have
similar requirements. Contact your local
fire agency or forest service for the laws
or regulations relating to fire protection
requirements.
WARNING
Never 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.
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.
14
FS 38
Approved Combinations of Cutting Attachment, Deflector, Handle and Harness
0000-GXX-0401-A4
1
6
7
5
2
3
4
Cutting Attachment Deflector Handle Harness
English
Approved Combinations
The complete combination includes:
– Cutting attachment
– Deflector
– Handle
– Harness
Select correct combination from the
table according to the cutting
attachment you intend to use.
WARNING
To reduce the risk of injury, no other
combinations are permitted.
Cutting Attachments
Mowing heads
1 STIHL AutoCut C 6-2
2 STIHL DuroCut 5-2
3 STIHL PolyCut 7-3
4 STIHL PolyCut 6-2
Deflector
5 Deflector with blade, for mowing
heads
Handle
6 Loop handle
Harness
7 Shoulder strap may be used
WARNING
Based on the cutting attachment being
used:
Choose the proper deflector in order to
reduce the risk of injury from thrown
objects and contact with the cutting
attachment.
Make sure your unit is equipped with the
proper handle and harness in order to
reduce the risk of injury from loss of
control and contact with the cutting
attachment.
Do not use rigid polymer blades, metal
cutting attachments or circular saw
blades on this unit.
Only mowing heads may be used on
loop-handled trimmers with a curved
drive tube.
FS 38
15
English
50 mm
234BA003 KN
5
1
3
4
A
(2")
2
1
239BA008 KN
234BA023 KN
234BA026 KN
A
Mounting the Loop Handle
The loop handle comes in two different
versions.
Version A
Mounting the loop handle
N Fit the loop handle (1) on the drive
tube at distance (A) of about 15 cm
(6 in.) from the control handle (2).
N Place the clamp (3) against the
drive tube and push it into the loop
handle.
N Place the square nut (4) in the loop
handle,
N insert the screw (5) from the other
side and tighten it down firmly.
Adjusting loop handle to most
comfortable position
N Loosen the screw (5).
N Move the loop handle along the
drive tube as required.
N Tighten down the screw (5) firmly.
Version B
Your new power tool comes with the
loop handle mounted on the drive tube,
but it must be turned and lined up to suit
your requirements.
Line up the loop handle.
N Loosen the screw (1)
N Turn the handle to the vertical
position.
The loop handle can be adjusted to suit
the height and reach of the operator and
the application by changing
distance (A).
Recommendation: distance (A):
about 15 cm (6 in)
N Slide the handle to the required
position.
N Tighten down the screw so that the
handle cannot be rotated on the
drive tube
16
FS 38
English
1
2
232BA066 KN
4
232BA067 KN
3
546BA016 KN
232BA033 KN
1
2
3
4
Mounting the Deflector
N Push the deflector (1) over the
clamp (2) as far as stop.
N Insert the nut (3 ) in the hex recess in
the deflector – make sure the holes
line up.
N Insert the screw (4) and tighten it
down firmly.
Mounting the Cutting
Attachment
Placing power tool on the ground
N Switch off the engine.
N Lay your trimmer on its back with
the loop handle and shroud pointing
down and the output shaft facing up.
Thrust Plate
The thrust plate (1) is shipped with the
DuroCut 5-2 and PolyCut 6-3. It is only
required for these mowing heads.
STIHL AutoCut 5-2 mowing head,
STIHL AutoCut C 5-2 mowing head
N Pull the thrust plate (1), if fitted, off
the shaft (2).
STIHL PolyCut 5-2 mowing head,
STIHL FixCut 6-3 mowing head
N Slip the thrust plate (1) over the
shaft (2) and engage the hex
recess (3) on the external
hexagon (4).
FS 38
17
English
6
6
546BA017 KN
5
1
002BA385 KN
Blocking the Shaft
N To block the shaft, insert a suitable
tool (5) through the holes (6) in the
deflector and thrust plate – turn the
thrust plate back and forth if
necessary.
Fitting the mowing head with screw
mounting
Keep the supplement sheet for the
mowing head in a safe place.
N Fit the thrust plate
N Screw the mowing head
counterclockwise on to the shaft (1)
as far as it will go
N Retain the shaft
N Tighten the mowing head
NOTICE
Remove the tool that was used to block
the shaft.
Removing the Mowing Head
N Retain the shaft
N Turn the mowing head
counterclockwise
Fitting Mowing Head without Screw
Mounting
Keep the supplement sheet for the
mowing head in a safe place!
STIHL AutoCut C 6-2
1
2
3
4
0000-GXX-3937-A0
N Place the mowing head (2) on the
shaft (3) while inserting the internal
hexagon (2) on the hexagon (4)
N Hold the mowing head (2) with your
hand.
N Turn cap (1) clockwise and tighten it
firmly by hand.
18
FS 38
English
11
5
681BA019 KN
10
STIHL PolyCut 6-2, PolyCut 7-3
N Push thrust plate onto the shaft
N Insert the nut (10) into the mowing
head
N Turn the mowing head (11)
clockwise until it engages the shaft
(5)
N Retaining the Shaft
N Tighten the mowing head
WARNING
Nuts that move too easily must be
replaced.
NOTICE
Remove the tool that was used to block
the shaft.
Removing the Mowing Head
STIHL AutoCut
N Hold the spool housing steady
N Unscrew the cap counterclockwise.
STIHL PolyCut
N Retaining the Shaft
N Turn the mowing head
counterclockwise
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 two-stroke air
cooled engine oil.
Use mid-grade unleaded gasoline with a
minimum octane rating of 89 ((R+M)/2)
and no more than 10% ethanol content.
NOTICE
Fuel with an octane rating below 89 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 damage the
engine. For this reason STIHL
recommends that you use only quality
unleaded gasoline!
NOTICE
Gasoline with an ethanol content of
more than 10% can cause running
problems and major damage in engines
and should not be used.
For further details, see
www.STIHLusa.com/ethanol
The ethanol content in gasoline affects
engine speed – it may be necessary to
readjust the carburetor if you use fuels
with various ethanol contents.
FS 38
19
English
WARNING
To reduce the risk of personal injury
from loss of control and/or contact with
the running cutting tool, do not use your
unit with an incorrect idle adjustment. At
correct idle speed, the cutting tool
should not move.
If your machine’s idle speed is
incorrectly adjusted, have your
authorized STIHL servicing dealer
check your machine and make the
proper adjustments and repairs.
The idle speed and maximum speed of
the engine change if you switch from a
fuel with a certain ethanol content to a
fuel with a much higher or lower ethanol
content.
This problem can be avoided by always
using fuel with the same ethanol
content.
To ensure the maximum performance of
your STIHL engine, use a high quality 2cycle engine oil. To help your engine run
cleaner and reduce harmful carbon
deposits, STIHL recommends using
STIHL HP Ultra 2-cycle engine oil or ask
your dealer for an equivalent fully
synthetic 2-cycle engine oil.
To meet the requirements of EPA and
CARB we recommend to use STIHL HP
Ultra oil.
STIHL MotoMix
STIHL recommends the use of STIHL
MotoMix. STIHL MotoMix has a high
octane rating and ensures that you
always use the right gasoline/oil mix
ratio.
STIHL MotoMix uses STIHL HP Ultra
two-stroke engine oil suited for high
performance engines.
For further details, see
www.STIHLusa.com/ethanol
If not using MotoMix, use only STIHL
two-stroke engine oil or equivalent highquality two-stroke engine oils that are
designed for use in air cooled two-cycle
engines.
The use of non-seasonal gasoline
blends may increase the potential for
pressure to build in the fuel tank during
operation. For example, using a winter
blend during the summer will increase
pressure in the fuel tank. Always use
gasoline blends appropriate to the
season, altitude and other
environmental factors.
Do not use NMMA 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.).
WARNING
Take care when handling gasoline.
Avoid direct contact with the skin and
avoid inhaling fuel vapor. When filling at
the pump, first remove the container
from your vehicle and place the
container on the ground before filling. To
reduce the risk of sparks from static
discharge and resulting fire and/or
explosion, do not fill fuel containers that
are sitting in or on a vehicle or trailer.
The container should be kept tightly
closed in order to limit the amount of
moisture that gets into the mixture.
The machine's fuel tank should be
cleaned as necessary.
Fuel mix ages
If not using MotoMix, only mix sufficient
fuel for a few days of work, not to exceed
30 days of storage. Store in approved
fuel-containers only. When mixing, pour
oil into the container first, and then add
gasoline. Close the container and shake
it by hand to ensure proper mix of oil and
gasoline.
WARNING
Shaking fuel can cause pressure to build
in the fuel container. To reduce the risk
of fire and severe personal injury or
property damage from fuel spraying,
allow the fuel container to sit for several
minutes before opening. Open the
container slowly to release any residual
pressures. Never open the fuel
container in the vicinity of any ignition
source. Read and follow all warnings
and instructions that accompany your
fuel container.
Gasoline
US gal. US fl.oz.
12.6
2 1/2 6.4
5 12.8
Dispose of empty mixing-oil containers
only at authorized disposal locations.
Oil (STIHL 50:1 or equivalent high-quality oils)
20
FS 38
English
232BA046 KN
002BA447 KN
Fueling
WARNING
Removing the cap on a pressurized fuel
tank can result in gasoline, vapors and
fumes being forcefully sprayed out from
the tank in all directions. The escaping
gasoline, vapors or fumes, sometimes
referred to as fuel spraying or
"geysering," can cause serious personal
injury, including fire and burn injury, or
property damage.
Fuel spraying can occur when the
engine is hot and the tank is opened
while under pressure. It can occur in hot
environments even if the engine has not
been running. Spraying is more likely to
occur when the fuel tank is half full or
more.
Avoid Injuries from Fuel Spraying.
Always follow the fueling instructions in
this manual:
– Treat every fuel tank as if it is
pressurized, particularly if it is half
full or more.
– Always allow the power tool to cool
adequately before attempting to
open the fuel tank or refueling; this
will take longer in hot conditions.
– Never remove the cap by turning it
directly to the open position. Turn it
first approximately 1/2 of a turn
counter-clockwise to relieve any
residual pressure.
– Never open the fuel tank while the
engine is still hot or running.
– Never open the fuel tank or re-fuel
the power tool near any sparks,
flames or other ignition sources.
– Pick the right fuel: use only good
quality (89 octane or higher), fresh
fuel blended for the season.
– Vapor lock: do not remove the fuel
cap in an effort to relieve vapor lock.
Removing the cap has no effect on
vapor lock.
– Be aware that fuel spraying is more
likely at higher altitudes.
Preparations
N Before fueling, clean the filler cap
and the area around it to ensure that
no dirt falls into the tank.
N Position the machine so that the
filler cap is facing up.
WARNING
In order to reduce the risk of fire and
other personal injury from escaping gas
vapor and fumes, remove the fuel filler
cap slowly and carefully so as to allow
any pressure build-up in the tank to
release slowly.
Opening
WARNING
After allowing the power tool to cool,
remove the fuel filler cap slowly and
carefully to allow any remaining
pressure build-up in the tank to release:
N While maintaining steady,
downward pressure, slowly turn the
cap approximately a 1/2 turn
counter-clockwise.
N If any significant venting occurs,
immediately re-seal the tank by
turning the cap clockwise to the
closed position. Allow the power
tool to cool further before attempting
to open the tank.
N Turn the cap to the open position
only after the contents of the tank
are no longer under pressure.
N Remove the fuel filler cap.
FS 38
21
English
002BA448 KN
2
232BA080 KN
1
6
7
5
4
3
WARNING
Never remove the cap by turning it
directly to the open position. First allow
the power tool to cool adequately and
then release any residual pressure by
slowly turning the cap approximately
1/2 turn counter-clockwise. Never
attempt to remove the cap while the
engine is still hot or running.
Refueling
Take care not to spill fuel while fueling
and do not overfill the tank – leave
approximately 1/2" (13 mm) air space.
Closing
WARNING
An improperly tightened fuel filler cap
can loosen or come off and spill
quantities of fuel. To reduce the risk of
fuel spillage and fire from an improperly
installed fuel cap, tighten the fuel filler
cap by hand with as much force as
possible:
N If your fuel cap still does not tighten
properly, it may be damaged or
broken. Stop using the power tool
and take it to your authorized STIHL
dealer for repair or replacement.
Starting / Stopping the
Engine
Controls
1 Stop switch
2 Throttle trigger lockout
3 Throttle trigger
4 Tongue of throttle trigger
5 Catch
Positions of stop switch
6I – normal run position – the engine
is running or can start
70 – Stop – engine off – the ignition is
switched off
22
FS 38
English
233BA047 KN
4
9
8
232BA011 KN
232BA012 KN
232TI013 KN
Starting
N Move the stop switch to I.
N Press down the throttle trigger
lockout and hold it there.
N Squeeze the throttle trigger until the
catch on the tongue (4) can be
engaged on the housing (arrow).
N Now release the throttle trigger,
tongue and trigger lockout in that
order. This is the starting throttle
position.
N Set the choke lever (8) to
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 manual fuel pump
bulb (9) at least five times – even if
the bulb is filled with fuel.
Cranking
N Place the unit on the ground: It must
rest securely on the engine support
and the deflector.
To reduce the risk of accidents, check
that the cutting attachment is not
touching the ground of any other
obstacles.
N Make sure you have a firm footing,
either standing, stooping or
kneeling.
N Hold the unit firmly on the ground
with your left hand and press down
– thumb under the fan housing – do
not touch the throttle trigger or
trigger lockout.
FS 38
NOTICE
Do not stand or kneel on the drive tube.
23
English
232BA014 KN
8
232TI015 KN
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.
NOTICE
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 Continue cranking.
When engine begins to fire
N After no more than five pulls, move
the choke lever (8) to e and
N continue cranking.
As soon as the engine runs
N Squeeze the throttle trigger to
disengage the tongue – the engine
will settle down to idle speed.
WARNING
Make sure the carburetor is correctly
adjusted. The cutting attachment must
not rotate when the engine is idling.
Your machine is now ready for
operation.
Stopping the Engine
N Move the stop switch to 0.
If engine does not start
N Set choke lever to e and
N move the stop switch to I, throttle
trigger lockout 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 stop switch to 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 stop switch to I.
N Set choke lever to e – even if the
engine is cold.
N Now start the engine.
Fuel tank run until completely dry
N After refueling, press the manual
fuel pump bulb at least five times –
even if the bulb is filled with fuel.
N Set the choke lever to suit the
engine temperature.
N Now start the engine.
24
Choke lever
If you did not move the choke lever
quickly enough to e after the engine
began to fire, the engine is flooded.
FS 38
Operating Instructions Cleaning the Air Filter
232BA017 KN
1
2
232BA018 KN
4
3
English
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 periods – see "Storing the
Machine".
If there is a noticeable loss of engine
power
N Set the choke lever to g.
N Press in the tab (1) and swing the
filter cover (2) down.
N Clean away loose dirt from around
the filter.
N Remove the felt element (3) from
the filter housing (4) and replace it –
knock out or blow out as a
temporary measure – do not wash.
N Replace damaged parts.
N Fit the felt element (3) in the filter
housing (4).
N Close the filter cover so that it snaps
into position.
FS 38
25
English
L
H
LA
233BA050 KN
Engine Management Adjusting the Carburetor
Exhaust emissions are controlled by the
design of the engine and components
(e.g. carburation, ignition, timing and
valve or port timing).
General Information
The carburetor comes from the factory
with a standard setting.
This setting provides an optimum fuel-air
mixture under most operating
conditions.
Preparations
N Shut off the engine.
N Mounting the cutting attachment.
N Check the air filter and clean or
replace if necessary.
N Check the spark arresting screen in
the muffler and clean or replace if
necessary. STIHL recommends that
you have servicing and repair work
carried out exclusively by an
authorized STIHL servicing dealer.
Standard setting
N Turn high speed screw (H)
counterclockwise as far as stop (no
more than 3/4 turn).
N Turn the low speed screw (L)
carefully clockwise as far as stop,
then turn it back 3/4 turn.
26
Adjust idle speed
N Carry out the standard setting.
N Start and warm up the engine.
Engine stops while idling
N Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly – the cutting
attachment must not rotate.
FS 38
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