STIHL FS 400, 450
Instruction Manual
Contents
English
Guide to Using this Manual 2
Safety Precautions and Working
Techniques 2
Approved Combinations of Cutting
Attachment, Deflector, Limit Stop
and Harness 13
Mounting the Bike Handle 15
Adjusting the Throttle Cable 16
Mounting the Deflector 16
Original Instruction ManualPrinted on chlorine-free paper
Mounting the Cutting Attachment 18
Fuel 22
Fueling 23
Fitting the Full Harness 24
Balancing the Machine 24
Starting / Stopping the Engine 24
Operating Instructions 27
Cleaning the Air Filter 27
Adjusting the Carburetor 27
Winter Operation 29
Electric Handle Heating 29
Spark Plug 30
Engine Running Behavior 31
Printing inks contain vegetable oils, paper can be recycled.
Lubricating the Gearbox 31
Storing the Machine 31
Sharpening Metal Cutting Blades 32
Maintaining the Mowing Head 32
Maintenance and Care 34
Minimize Wear and Avoid Damage 36
Main Parts 37
Specifications 38
Maintenance and Repairs 40
Disposal 40
EC Declaration of Conformity 41
Dear Customer,
Thank you for choosing a quality
engineered STIHL product.
It has been built using modern
production techniques and
comprehensive quality assurance.
Every effort has been made to ensure
your satisfaction and trouble-free use of
the product.
Please contact your dealer or our sales
company if you have any queries
concerning this product.
Your
Dr. Nikolas Stihl
© ANDREAS STIHL AG & Co. KG, 2020
0458-255-0121-B. VB0.L19.
0000006368_018_GB
FS 400, FS 450
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 the machine are explained in
this manual.
Depending on the model concerned, the
following pictograms may be attached to
your machine.
Fuel tank; fuel mixture of
gasoline and engine oil
Operate decompression
valve
Manual fuel pump
Operate manual fuel
pump
Tube of grease
Intake air: Summer
operation
Intake air: Winter
operation
Handle heating
Symbols in text
WARNING
Warning where there is a risk of an
accident or personal injury or serious
damage to property.
NOTICE
Caution where there is a risk of
damaging the machine or its individual
components.
Engineering improvements
STIHL's philosophy is to continually
improve all of its products. For this
reason we may modify the design,
engineering and appearance of our
products periodically.
Therefore, some changes, modifications
and improvements may not be covered
in this manual.
Safety Precautions and
Working Techniques
Some special safety precautions must be
observed to reduce the
risk of personal injury
when operating this
power tool because of the
very high speed of its cutting attachment.
It is important that you
read the instruction manual before first use and
keep it in a safe place for
future reference. Nonobservance of the
instruction manual may
result in serious or even
fatal injury.
Observe all applicable local safety
regulations, standards and ordinances.
If you have not used this type of power
tool before: Have your dealer or other
experienced user show you how to
operate your machine or attend a
special course in its operation.
Minors should never be allowed to use a
power tool.
Keep bystanders, especially children,
and animals away from the work area.
When the power tool is not in use, shut it
off so that it does not endanger others.
Secure it against unauthorized use.
The user is responsible for avoiding
injury to third parties or damage to their
property.
2
FS 400, FS 450
English
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.
The use of noise emitting power tools
may be restricted to certain times by
national or local regulations.
To operate the power tool you must be
rested, in good physical condition and
mental health.
If you have any condition that might be
aggravated by strenuous work, check
with your doctor before operating a
power tool.
Persons with pacemakers only: The
ignition system of your power tool
produces an electromagnetic field of a
very low intensity. This field may
interfere with some pacemakers. STIHL
recommends that persons with
pacemakers consult their physician and
the pacemaker manufacturer to reduce
any health risk.
Do not operate the power tool if you are
under the influence of any substance
(drugs, alcohol) which might impair
vision, dexterity or judgment.
Depending on the cutting attachment
fitted, use your power tool only for
cutting grass, wild growth, shrubs,
scrub, bushes, small diameter trees and
similar materials.
Do not use your power tool for any other
purpose because of the increased risk of
accidents.
Only use cutting attachments and
accessories that are explicitly approved
for this power tool model by STIHL or
are technically identical. If you have any
questions in this respect, consult a
servicing dealer. Use only high quality
tools and accessories in order to avoid
the risk of accidents and damage to the
machine.
STIHL recommends the use of genuine
STIHL tools and accessories. They are
specifically designed to match the
product and meet your performance
requirements.
Never attempt to modify your power tool
in any way since this may increase the
risk of personal injury. STIHL excludes
all liability for personal injury and
damage to property caused while using
unauthorized attachments.
Do not use a pressure washer to clean
the unit. The solid jet of water may
damage parts of the unit.
The deflector on this power tool cannot
protect the operator from all objects
thrown by the cutting attachment
(stones, glass, wire, etc.). Such objects
may ricochet and then hit the operator.
Clothing and Equipment
Wear proper protective clothing and
equipment.
Clothing must be sturdy
but allow complete freedom of movement. Wear
snug-fitting clothing, an
overall and jacket combination, do not wear a
work coat.
Avoid clothing that could
get caught on branches
or brush or moving parts
of the machine. Do not
wear a scarf, necktie or
jewelry. Tie up and confine long hair (e.g. with a
hair net, cap, hard hat,
etc.).
Wear steel-toed safety
boots with non-slip soles.
Sturdy shoes with non-slip soles may be
worn as an alternative only when using
mowing heads.
WARNING
To reduce the risk of eye
injuries, wear snug-fitting
safety glasses in accordance with European
Standard EN 166. Make
sure the safety glasses
are a good fit.
Wear a face shield and make sure it is a
good fit. A face shield alone does not
provide adequate eye protection.
Wear hearing protection, e.g. earplugs
or ear muffs.
Wear a safety hard hat for thinning
operations, when working in high scrub
and where there is a danger of head
injuries from falling objects.
Wear heavy-duty work
gloves made of durable
material (e.g. leather).
FS 400, FS 450
3
English
002BA079 KN
STIHL offers a comprehensive range of
personal protective clothing and
equipment.
Transporting the Power Tool
Always turn off the engine.
Carry the unit hanging from the shoulder
strap or properly balanced by the drive
tube.
To reduce the risk of cut injuries, fit
transport guard on the cutting
attachment, even when carrying the tool
for short distances – see also
"Transporting the Unit".
To reduce the risk of serious burn injuries, avoid
touching hot parts of the
machine, including the
gearbox housing.
Transporting by vehicle: Properly secure
your power tool to prevent turnover, fuel
spillage and damage.
Fueling
Gasoline is an extremely
flammable fuel. Keep
clear of naked flames. Do
not spill any fuel – do not
smoke.
Always shut off the engine before
refueling.
Do not fuel a hot engine – fuel may spill
and cause a fire.
Open the fuel cap carefully to allow any
pressure build-up in the tank to release
slowly and avoid fuel spillage.
Fuel your power tool only in wellventilated areas. If you spill fuel, wipe
the machine immediately – if fuel gets on
your clothing, change immediately.
After fueling, tighten
down the fuel tank cap as
securely as possible.
This reduces the risk of unit vibrations
causing the fuel cap to loosen or come
off and spill quantities of fuel.
To reduce the risk of serious or fatal
burn injuries, check for fuel leakage. If
fuel leakage is found, do not start or run
the engine until leak is fixed.
Before Starting
Check that your power tool is properly
assembled and in good condition – refer
to appropriate chapters in the instruction
manual.
– Check the fuel system for leaks,
paying special attention to visible
parts such as the tank cap, hose
connections and the manual fuel
pump (on machines so equipped). If
there are any leaks or damage, do
not start the engine – risk of fire.
Have your machine repaired by a
servicing dealer before using it
again.
– Use only an approved combination
of cutting attachment, deflector,
handle and harness. All parts must
be assembled properly and
securely.
– Slide control / stop switch must
move easily to STOP or 0.
– Smooth action of throttle trigger
lockout (if fitted) and throttle trigger
– the throttle trigger must return
automatically to the idle position.
– Check that the spark plug boot is
secure – a loose boot may cause
arcing that could ignite combustible
fumes and cause a fire.
– Check cutting tool or attachment for
correct and secure assembly and
good condition.
4
FS 400, FS 450
English
002BA055 KN
002BA080 KN
– Check protective devices (e.g.
deflector for cutting attachment,
rider plate) for damage or wear.
Always replace damaged parts. Do
not operate your machine with a
damaged deflector or worn rider
plate (lettering and arrows no longer
legible).
– Never attempt to modify the controls
or safety devices in any way.
– Keep the handles dry and clean –
free from oil and dirt – for safe
control of the power tool.
– Adjust the harness and handle(s) to
suit your height and reach. See
chapters on "Fitting the Harness"
and "Balancing the
Trimmer/Brushcutter".
To reduce the risk of accidents, do not
operate your power tool if it is damaged
or not properly assembled.
If you use a shoulder strap or full
harness: Practice removing and putting
down the power tool as you would in an
emergency. To avoid damage, do not
throw the power tool to the ground when
practicing.
Start the engine.
Start the engine at least 3 meters from
the fueling spot, outdoors only.
Place the unit on firm ground in an open
area. Make sure you have good balance
and secure footing. Hold the unit
securely. The cutting attachment must
be clear of the ground and all other
obstructions because it may begin to run
when the engine starts.
Your power tool is a one-person unit. To
reduce the risk of injury from thrown
objects, do not allow other persons
within a radius of 15 meters of your own
position – even when starting.
To reduce the risk of
injury, avoid contact with
the cutting attachment.
Do not drop start the
power tool – start the
engine as described in
the instruction manual.
Note that the cutting
attachment continues to
run for a short period
after you let go of the
throttle trigger – flywheel
effect.
Check idle speed setting: The cutting
attachment must not rotate when the
engine is idling with the throttle trigger
released.
To reduce the risk of fire, keep hot
exhaust gases and hot muffler away
from easily combustible materials (e.g.
wood chips, bark, dry grass, fuel).
Holding and Controlling the Power Tool
Always hold the power tool firmly with
both hands on the handles.
Make sure you always have good
balance and secure footing.
Models with bike handle
Right handle on control handle, left hand
on left handle.
Models with loop handle
On models with a loop handle and
barrier bar, left hand on loop handle,
right hand on control handle, even if you
are left-handed.
During Operation
Make sure you always have good
balance and secure footing.
In the event of impending danger or in
an emergency, switch off the engine
immediately by moving the slide control
/ stop switch to STOP or 0.
FS 400, FS 450
5
English
15m (50ft)
The cutting attachment may catch and
fling objects a great distance and cause
injury - therefore, do not allow any other
persons within a radius of 15 meters of
your own position. To reduce the risk of
damage to property, also maintain this
distance from other objects (vehicles,
windows). Even maintaining a distance
of 15 meters or more cannot exclude the
potential danger.
The correct engine idle speed is
important to ensure that the cutting
attachment stops rotating when you let
go of the throttle trigger.
Check and correct the idle speed setting
regularly. If the cutting attachment
continues to rotate when the engine is
idling, have the machine checked by
your servicing dealer. STIHL
recommends an authorized STIHL
servicing dealer.
Take special care in slippery conditions
(ice, wet ground, snow), on slopes or
uneven ground.
Watch out for obstacles: Roots and tree
stumps which could cause you to trip or
stumble.
Always stand on the ground while
working, never on a ladder, work
platform or any other insecure support.
Be particularly alert and cautious when
wearing hearing protection because
your ability to hear warnings (shouts,
alarms, etc.) is restricted.
To reduce the risk of accidents, take a
break in good time to avoid tiredness or
exhaustion.
Work calmly and carefully – in daylight
conditions and only when visibility is
good. Stay alert so as not to endanger
others.
Your power tool produces
toxic exhaust fumes as
soon as the engine is
running. These fumes
may be colorless and
odorless and contain
unburned hydrocarbons
and benzol. Never run
the engine indoors or in
poorly ventilated locations, even if your model
is equipped with a catalytic converter.
To reduce the risk of serious or fatal
injury from breathing toxic fumes,
ensure proper ventilation when working
in trenches, hollows or other confined
locations.
To reduce the risk of accidents, stop
work immediately in the event of
nausea, headache, visual disturbances
(e.g. reduced field of vision), problems
with hearing, dizziness, deterioration in
ability to concentrate. Apart from other
possibilities, these symptoms may be
caused by an excessively high
concentration of exhaust gases in the
work area.
Operate your power tool so that it
produces a minimum of noise and
emissions – do not run the engine
unnecessarily, accelerate the engine
only when working.
To reduce the risk of fire, do not smoke
while operating or standing near your
power tool. Note that combustible fuel
vapor may escape from the fuel system.
The dusts, vapor and smoke produced
during operation may be dangerous to
health. If the work area is very dusty or
smoky, wear a respirator.
If your power 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 – see also
"Before Starting".
Check the fuel system in particular for
leaks and make sure the safety devices
are working properly. Do not continue
operating your power tool if it is
damaged. In case of doubt, consult your
servicing dealer.
Do not operate your power tool in the
starting throttle position – engine speed
cannot be controlled in this position.
To reduce the risk
of injury from
thrown objects,
never operate the
unit without the
proper deflector for
the type of cutting
attachment being
used.
6
FS 400, FS 450
English
Inspect the work area:
Stones, pieces of metal
or other solid objects may
be thrown more than 15
meters and cause personal injury or damage
the cutting attachment
and property (e.g. parked
vehicles, windows).
Special care must be taken when
working in difficult, over-grown terrain.
When cutting high scrub, under bushes
and hedges: Keep cutting attachment at
a minimum height of 15 cm to avoid
harming small animals.
Always shut off the engine before
leaving the unit unattended.
Check the cutting attachment at regular
short intervals during operation or
immediately if there is a noticeable
change in cutting behavior:
– Turn off the engine. Hold the unit
firmly and wait for the cutting
attachment to come to a standstill.
– Check condition and tightness, look
for cracks.
– Check sharpness.
– Replace damaged or dull cutting
attachments immediately, even if
they have only superficial cracks.
Clean grass and plant residue off the
cutting attachment mounting at regular
intervals – remove any build up of
material from the cutting attachment and
deflector.
To reduce the risk of injury, shut off the
engine before replacing the cutting
attachment.
The gearbox becomes
hot during operation. To
reduce the risk of burn
injury, do not touch the
gearbox housing.
When using mowing heads
Equip the deflector with the additional
components specified in the instruction
manual.
Use only the deflector with properly
mounted line limiting blade to ensure the
mowing lines are automatically trimmed
to the approved length.
To reduce the risk of injury, always turn
off the engine before adjusting the nylon
line of manually adjustable mowing
heads
Using the unit with over-long nylon
cutting lines reduces the engine's
operating speed. The clutch then slips
continuously and this causes
overheating and damage to important
components (e.g. clutch, polymer
housing components) – and this can
increase the risk of injury from the
cutting attachment rotating while the
engine is idling.
Using metal cutting attachments
STIHL recommends the use of original
STIHL metal cutting attachments. They
are specifically designed to match your
model and meet your performance
requirements.
Metal cutting attachments rotate at very
high speed. The forces that occur act on
the machine, the attachment and the
material being cut.
Sharpen metal cutting attachments
regularly as specified.
Unevenly sharpened metal cutting
attachments cause out-of-balance
which can impose extremely high loads
on the machine and increase the risk of
breakage.
Dull or improperly sharpened cutting
edges can put a higher load on the
cutting attachment and increase the risk
of injury from cracked or broken parts.
Inspect metal cutting attachments for
cracks or warping after every contact
with hard objects (e.g. stones, rocks,
pieces of metal). To reduce the risk of
injury, remove burrs and other visible
build-ups of material (use a file) because
they may become detached and be
thrown at high speed during operation.
If a rotating metal cutting attachment
makes contact with a rock or other solid
object there is a risk of sparking which
may cause easily combustible material
to catch fire under certain
circumstances. Dry plants and scrub are
also easily combustible, especially in hot
and dry weather conditions. If there is a
risk of fire, do not use metal cutting
attachments near combustible
materials, dry plants or scrub. Always
contact your local forest authority for
information on a possible fire risk.
Do not continue using or attempt to
repair damaged or cracked cutting
attachments by welding, straightening or
modifying the shape (out of balance).
This may cause parts of the cutting
attachment to come off and hit the
operator or bystanders at high speed
and result in serious or fatal injuries.
FS 400, FS 450
7
English
To reduce the above-mentioned risks
when using a metal cutting attachment,
never use a metal cutting attachment
with a diameter larger than specified. It
must not be too heavy. It must be
manufactured from materials of
adequate quality and its geometry must
be correct (shape, thickness).
To reduce the risk of injury, a metal
cutting attachment not manufactured by
STIHL must not be heavier, thicker,
have a different shape or a diameter
larger than the largest metal cutting
attachment approved by STIHL for this
power tool model.
Vibrations
Prolonged use of the power tool may
result in vibration-induced circulation
problems in the hands (whitefinger
disease).
No general recommendation can be
given for the length of usage because it
depends on several factors.
The period of usage is prolonged by:
– Hand protection (wearing warm
gloves)
– Work breaks
The period of usage is shortened by:
– Any personal tendency to suffer
from poor circulation (symptoms:
frequently cold fingers, tingling
sensations).
– Low outside temperatures.
– The force with which the handles
are held (a tight grip restricts
circulation).
Continual and regular users should
monitor closely the condition of their
hands and fingers. If any of the above
symptoms appear (e.g. tingling
sensation in fingers), seek medical
advice.
Maintenance and Repairs
Service the machine regularly. Do not
attempt any maintenance or repair work
not described in the instruction manual.
Have all other work performed by a
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer. STIHL dealers are
regularly given the opportunity to attend
training courses and are supplied with
the necessary technical information.
Only use high-quality replacement parts
in order to avoid the risk of accidents
and damage to the machine. If you have
any questions in this respect, consult a
servicing dealer.
STIHL recommends the use of genuine
STIHL replacement parts. They are
specifically designed to match your
model and meet your performance
requirements.
To reduce the risk of injury, always shut
off the engine before carrying out any
maintenance or repairs or cleaning the
machine. – Exception: Carburetor and
idle speed adjustments.
Do not turn the engine over on the
starter with the spark plug boot or spark
plug removed unless the slide control /
stop switch is on STOP or 0 since there
is otherwise a risk of fire from
uncontained sparking.
To reduce the risk of fire, do not service
or store your machine near open flames.
Check the fuel filler cap for leaks at
regular intervals.
Use only a spark plug of the type
approved by STIHL and make sure it is
in good condition – see "Specifications".
Inspect the ignition lead (insulation in
good condition, secure connection).
Check the condition of the muffler.
To reduce the risk of fire and damage to
hearing, do not operate your machine if
the muffler is damaged or missing.
Do not touch a hot muffler since burn
injury will result.
Vibration behavior is influenced by the
condition of the AV elements – check the
AV elements at regular intervals.
Symbols on Deflectors
An arrow on the deflector shows the
correct direction of rotation of the cutting
attachments.
Use deflector in
combination with
mowing heads
only. Do not use
metal cutting
attachments.
8
FS 400, FS 450
English
002BA364 KN
000BA015 KN
681BA209 KN
Harness / Strap
The harness is included in the scope of
supply or available as a special
accessory.
N Use a shoulder strap.
N With the engine running, attach the
machine to the shoulder strap.
Grass cutting blades, brush knives and
shredder blades must always be used in
combination with a full harness.
Circular saw blades must always be
used in combination with a full harness
with a quick-release system.
Mowing Head with Nylon Line
Nylon line achieves a soft cut for edging
and trimming around trees, fence posts,
etc. – less risk of damaging tree bark.
The mowing head comes with an
instruction leaflet. Refill the mowing
head with nylon line as described in the
instruction leaflet.
WARNING
To reduce the risk of serious injury,
never use wire or metal-reinforced line in
place of the nylon line.
If one of the wear limit marks imbedded
in the baseplate of the DuroCut
(exclamation marks) becomes visible,
do not continue using the mowing head
since it may otherwise be damaged.
Replace the worn baseplate.
The mowing head comes with
instruction leaflets. Equip the mowing
head only with nylon line as described in
the instruction leaflets.
WARNING
Never use wire in place of the nylon
mowing line – risk of injury.
STIHL Polycut Mowing Head with
Polymer Blades
For mowing unobstructed edges of
meadows (without posts, fences, trees
or similar obstacles).
Check the wear limit marks!
FS 400, FS 450
STIHL DuroCut
Check the wear limit marks!
9
English
002BA396 KN
002BA135 KN
000BA020 KN
If one of the wear limit marks on the
PolyCut mowing head is worn through
(arrow): Do not continue using the
mowing head. Install a new one. There
is otherwise a risk of injury from thrown
parts of the head.
It is important to follow the maintenance
instructions for the PolyCut mowing
head.
The PolyCut can also be equipped with
mowing line in place of the polymer
blades.
The mowing head comes with
instruction leaflets. Equip the mowing
head with polymers blades or nylon line
as described in the instruction leaflets.
WARNING
Never use wire in place of the nylon
mowing line – risk of injury.
Risk of Kickout (Blade Thrust) with Metal
Cutting Attachments
WARNING
When using metal cutting attachments there is
a risk of kickout when the
rotating blade comes into
contact with a solid object
such as a tree trunk,
branch, tree stump, rock
or similar. The machine is
thrown to the right or to
the rear – opposite to the
attachment's direction of
rotation.
The risk of kickout is greatest when the
black area of the rotating cutting
attachment comes into contact with a
solid object.
Grass Cutting Blade
Use for grass and weeds only – sweep
the brushcutter in an arc like a scythe.
WARNING
Improper use may damage the grass
cutting blade – risk of injury from thrown
parts.
Resharpen the grass cutting blade
according to instructions when it has
dulled noticeably.
10
Brush Knife
For cutting matted grass, wild growth
and scrub and thinning young stands
with a stem diameter of no more than
2 cm – do not cut thicker stems – risk of
accidents.
FS 400, FS 450
English
002BA355 KN
002BA509 KN
002BA210 KN
Use the brushcutter like a scythe (sweep
it to the right and left) at ground level
when cutting grass and thinning young
stands.
To cut wild growth and scrub, lower the
brush knife down onto the growth to
achieve a shredding effect – always
keep the cutting attachment below hip
level during this process.
Exercise extreme caution when using
this method of cutting. The higher the
cutting attachment is off the ground, the
greater the risk of injury from cuttings
being thrown sideways.
Warning! Improper use of a brush knife
may cause it to crack, chip or shatter –
risk of injury from thrown parts.
To reduce the risk of injury it is essential
to take the following precautions:
– Avoid contact with stones, rocks,
pieces of metal and other solid
foreign objects.
– Never cut wood or shrubs with a
stem diameter of more than 2 cm –
use a circular saw blade for such
work.
– Inspect the brush knife at regular
short intervals for signs of damage.
Do not continue working with a
damaged brush knife.
– Resharpen the brush knife regularly
and whenever it has dulled
noticeably, and have it balanced if
necessary (STIHL recommends a
STIHL servicing dealer).
Shredder Blade
Suitable for thinning and shredding
tough, matted grass and scrub.
To cut wild growth and scrub, lower the
shredder blade down onto the growth to
achieve a shredding effect – always
keep the cutting attachment below hip
level during this process.
Exercise extreme caution when using
this method of cutting. The higher the
cutting attachment is off the ground, the
greater the risk of injury from cuttings
being thrown sideways.
Warning! Improper use may damage the
shredder blade – risk of injury from
thrown parts.
To reduce the risk of injury it is essential
to take the following precautions:
– Avoid contact with stones, rocks,
pieces of metal and other solid
foreign objects.
– Never cut wood or shrubs with a
stem diameter of more than 2 cm –
use a circular saw blade for such
work.
– Inspect the shredder blade at
regular short intervals for signs of
damage. Do not continue working
with a damaged shredder blade.
– Resharpen the shredder blade
regularly and whenever it has dulled
noticeably, and have it balanced if
necessary (STIHL recommends a
STIHL servicing dealer).
Circular Saw Blade
For cutting shrubs and trees:
Up to a stem diameter of 4 cm when
used on brushcutters.
Up to a stem diameter of 7 cm when
used on clearing saws.
Before starting the cut, accelerate the
engine up to full throttle. Perform cut
with uniform pressure.
FS 400, FS 450
11
English
002BA068 KN
Use circular saw blades only with a
matching limit stop of the correct
diameter.
WARNING
To reduce the risk of blade damage,
avoid contact with stones and the
ground. Resharpen the blade properly in
good time – dull teeth may result in the
blade cracking and shattering and
causing serious injury.
When felling, maintain a distance of at
least two tree lengths from the next
felling site.
Risk of kickout
The risk of kickout is highest in the black
area of the blade: Do not use this area of
the circular saw blade for cutting.
There is also a risk of kickout when
using the lighter shaded areas of the
blade: These areas of the blade should
only be used by experienced operators
with specialized training.
STIHL recommends that you use the
non-shaded area of the circular saw
blade. Always start the cut with this area
of the blade.
12
FS 400, FS 450
Approved Combinations of Cutting Attachment, Deflector, Limit Stop and Harness
Cutting Attachment Deflector, Limit Stop Harness
16
English
1
2
3
4
18
17
23
9
5
6
8
7
19
9
20
10
21
11
12
23
13
FS 400, FS 450
14
15
22
0000-GXX-0375-A0
13
English
Approved Combinations
Select correct combination from the
table according to the cutting
attachment you intend to use.
WARNING
For safety reasons only the cutting
attachments and deflectors or limit stops
shown in each row of the table may be
used together. No other combinations
are permitted because of the risk of
accidents.
Cutting Attachments
Mowing heads
1 STIHL SuperCut 40-2
2 STIHL AutoCut 46-2
3 STIHL TrimCut 41-2
4 STIHL DuroCut 40-4
Metal cutting attachments
5 Grass cutting blade 230-4
(230 mm dia.)
6 Grass cutting blade 255-8
(255 mm dia.)
7 Grass cutting blade 250-40 Spezial
(250 mm dia.)
8 Brush knife 305-2 Spezial
(305 mm dia.)
9 Brush knife 300-3
(300 mm dia.)
10 Shredder blade 270-2
(270 mm dia.)
11 Scratcher tooth circular saw blade
200
(200 mm dia.)
12 Chisel tooth circular saw blade 200-
22 (4119), chisel tooth circular saw
blade 200-22 HP (4000)
13 Scratcher tooth circular saw blade
225
(225 mm dia.)
14 Chisel tooth circular saw blade 225
(225 mm dia.)
15 Carbide tipped circular saw blade
225
(225 mm dia.)
WARNING
Non-metal grass cutting blades, brush
knives, shredder blades and circular
saw blades are not approved.
Deflectors, Limit Stops
16 Deflector for mowing heads
17 Deflector with
18 skirt and blade, for mowing heads
19 Deflector without skirt and blade, for
metal cutting attachments 8 to 12
20 Deflector for shredder blade
21 Limit stop for circular saw blades,
items 14 and 15
22 Limit stop for circular saw blades,
items 16 and 18
1)
for FS 450 only
Harness
23 Full harness must be used
14
FS 400, FS 450
Mounting the Bike Handle
3
1
2
256BA001 KN
A
4
1
256BA002 KN
9
5
7
8
4
9
002BA256 KN
6
7
English
N Hold the lower clamp (1) steady.
N Unscrew and remove the clamping
screw (2). The clamps are loose
once the clamping screw has been
removed.
N Remove the upper clamp (3) from
the lower clamp.
FS 400, FS 450
N Place the handlebar (4) in the lower
clamp (1) so that distance A is no
more than 15 cm.
N Place the upper clamp in position
and press it down.
N Insert the clamping screw.
N Line up the handlebar at a right
angle to the drive tube.
N Tighten down the clamping screw
firmly.
N Take out the screw (5), the nut (6)
remains in the control handle (7).
N Push the control handle onto the
end of the handlebar (4) until the
holes (9) line up – the throttle
trigger (8) must point towards the
gearbox.
N Insert the screw and tighten it down
firmly.
N Go to "Adjusting the Throttle Cable".
Transport and storage position: Loosen
the clamping screw, turn the handlebar
in line with the drive tube and fold the
handles down.
15
English
002BA163 KN
STOP
249BA017 KN
1
2
002BA513 KN
1
002BA514 KN
2
002BA515 KN
2
002BA516 KN
3
Adjusting the Throttle Cable
Some machine versions are equipped
with a throttle cable adjuster on the
control handle.
A properly adjusted throttle cable is the
precondition for correct operation in the
full throttle, starting throttle and idle
positions.
Adjust the throttle cable only after the
unit is fully assembled – the control
handle must be in the normal operating
position.
N Use a suitable tool to push the slide
to the end of the slot (see
illustration).
Mounting the Deflector
Use the Right Deflector
WARNING
Deflector (2) may also be used for
mowing heads if it is equipped with the
skirt and line limiter blade, see
"Mounting Skirt and Blade".
WARNING
Deflector (1) is approved for mowing
heads only and must therefore be
mounted before fitting a mowing head.
WARNING
Deflector (3) is approved for shredder
blades only and must therefore be
mounted before fitting a shredder blade.
N Press down the throttle trigger
lockout (1) and squeeze the throttle
trigger (2) (full throttle) – this sets
the throttle cable correctly.
16
WARNING
Deflector (2) is approved for grass
cutting blades and brush knives only and
must therefore be mounted before fitting
a grass cutting blade or brush knife.
FS 400, FS 450
English
002BA517 KN
4
5
002BA520 KN
6
7
2
1
3
2
002BA526 KN
1
4
002BA527 KN
5
1
4
1
2
WARNING
The limit stop (4) is approved as a
deflector for circular saw blades only
and must therefore be mounted before
fitting a circular saw blade. It is also
necessary to change the guard ring (5),
see "Mounting the Cutting Attachment" /
"Mounting Circular Saw Blades".
Mounting the Deflector
Deflectors (1 to 4) are mounted to the
gearbox in the same way.
Fitting the Skirt
When using mowing heads
The deflector for metal mowing
attachments (1) must be equipped with
the skirt (2) when you use mowing
heads.
N Slide the lower guide slot (3) of the
skirt (2) onto the deflector (1) – it
must snap into position.
Mounting the Blade
When using nylon line mowing heads
The deflector for metal mowing
attachments (1) must be equipped with
the line limiter blade (4) when you use
nylon line mowing heads.
N Push the blade (4) into the upper
guide slot (5) on the skirt (2) and
line it up with the first hole.
N Insert the screw and tighten it down
firmly.
N Remove dirt from joints on gearbox
and deflector – make sure that no
dirt gets into the screw holes in the
gearbox.
N Place the deflector on the
gearbox (6).
N Insert the screws (7) and tighten
them down firmly.
FS 400, FS 450
17
English
002BA406 KN
002BA295 KN
1
2
3
4
1
2
1
681BA196 KN
2
Mounting the Cutting
Attachment
Placing power tool on the ground
N Shut off the engine.
N Lay your power tool on its back so
that the cutting attachment
mounting face is pointing up.
Mounting Hardware
The mounting hardware supplied
depends on the cutting attachment that
comes as original equipment with the
new machine.
The mounting hardware is fitted to the
gearbox for transportation and must be
removed before mounting a cutting
attachment.
Removing the Mounting Hardware
N Block the shaft.
N Use the combination wrench (1) to
loosen and remove the nut (2)
clockwise.
N Remove the rider plate (3) and
thrust washer (4) (where fitted).
Checking the Thrust Plate
The thrust plate is necessary for
mounting all cutting attachments to the
gearbox.
The thrust plate consists of the thrust
plate body (1) to which a captive guard
washer (2) is fitted.
WARNING
Never use a thrust plate without the
guard washer. Always replace a thrust
plate if the guard washer is missing.
Mounting the Guard Ring
Always fit the guard ring that matches
the cutting attachment you intend to use.
The following guard rings are either
fitted to the gearbox or are available as
special accessories.
18
FS 400, FS 450
English
2
1
3
002BA524 KN
2
1
002BA525 KN
1
2
002BA294 KN
Guard ring for mowing applications
For optimum protection from the ingress
of grass when using grass cutting blades
and brush knives
N Mount the guard ring (1) for mowing
applications.
N Fit the thrust plate (2) and the guard
washer (3).
Guard ring for sawing applications
For circular saw blades
N Fit the guard ring (1) for sawing
applications.
N Fit the thrust plate (2).
Cleaning the Gearbox and Cutting
Attachment Mounting Hardware
Block the shaft.
N Insert the stop pin (1) in the bore (2)
in the gearbox as far as stop, apply
slight pressure.
N Rotate the shaft until the stop pin
slips into position.
Mount the cutting attachment.
WARNING
Use a deflector that matches the cutting
attachment – see "Mounting the
Deflector".
Fitting Mowing Head with Screw
Mounting
FS 400, FS 450
Clean the gearbox, the area surrounding
it, i nside the grass shield and the cutting
attachment mounting hardware at
regular intervals. Also check for
contamination when changing the
cutting attachment and clean thoroughly
if necessary.
N Remove all cutting attachment
mounting hardware from the
gearbox for this purpose.
Keep the instruction leaflet for the
mowing head in a safe place.
19
English
1
002BA385 KN
681BA197 KN
1
2
681BA186 KN
002BA521 KN
b
2
3
1
4
a
WARNING
Wear protective gloves to reduce the
risk of direct contact with the sharp
cutting edges.
Grass Cutting Blades, Brush Knives
Aligning the cutting attachment
N Screw the mowing head
counterclockwise on to the shaft (1)
as far as stop.
N Block the shaft.
N Tighten down the mowing head
firmly.
NOTICE
Remove the tool used to block the shaft.
Removing the Mowing Head
N Block the shaft.
N Unscrew the mowing head
Removing and Installing Metal Cutting
Attachments
Before removing and installing metal
cutting attachments:
20
clockwise.
Cutting attachments with 2, 3 or 4 teeth
may point in either direction – these
cutting attachments must be turned over
regularly to help avoid one-sided wear.
The cutting edges of the grass cutting
blades 255-8 (1) and 250-40 Spezial (2)
must point clockwise.
Mounting the cutting attachment
N Fit the guard ring for mowing
applications.
N Place the cutting attachment (1) in
position.
WARNING
Collar (a) must locate in the cutting
attachment's mounting hole (b).
Securing the cutting attachment
N Fit the thrust washer (2) – convex
side must face up.
N Fit the rider plate (3) (for mowing
applications).
N Block the shaft.
N Screw the mounting nut (4) on to the
shaft counterclockwise and tighten
it down firmly.
WARNING
If the mounting nut has become too
loose, fit a new one.
FS 400, FS 450
English
a
1
002BA522 KN
3
4
2
b
3
b
681BA165 KN
b
002BA300 KN
3
4
1
2
a
NOTICE
Remove the tool used to block the shaft.
Removing the cutting attachment
N Block the shaft.
N Unscrew the mounting nut
clockwise.
N Pull the cutting attachment with its
mounting hardware off the gearbox.
Shredder Blade 270-2
Mounting the cutting attachment
N Fit the guard ring for mowing
applications.
WARNING
Collar (a) must locate in the cutting
attachment's mounting hole (b).
Securing the cutting attachment
N Fit the thrust washer (2) – convex
side must face up.
N Fit the guard ring (3).
N Block the shaft.
N Screw the mounting nut (4) on to the
shaft counterclockwise and tighten
it down firmly.
WARNING
If the mounting nut has become too
loose, fit a new one.
NOTICE
Remove the tool used to block the shaft.
Removing the cutting attachment
N Block the shaft.
N Unscrew the mounting nut
clockwise.
N Pull the cutting attachment with its
mounting hardware off the gearbox.
Circular Saw Blades 200 and 225
Aligning the cutting attachment
Cutting edges of circular saw blades
must point clockwise.
Mounting the cutting attachment
N Fit the guard ring for sawing
applications.
N Place the shredder blade (1) in
position – the cutting edges must
point upwards.
FS 400, FS 450
N Place the cutting attachment (1) in
position.
21
English
WARNING
Collar (a) must locate in the cutting
attachment's mounting hole (b).
Securing the cutting attachment
N Fit the thrust washer (2) – convex
side must face up.
N Fit the rider plate (3) (for sawing
applications).
N Block the shaft.
N Screw the mounting nut (4) on to the
shaft counterclockwise and tighten
it down firmly.
WARNING
If the mounting nut has become too
loose, fit a new one.
NOTICE
Remove the tool used to block the shaft.
Removing the cutting attachment
N Block the shaft.
N Unscrew the mounting nut
clockwise.
N Pull the cutting attachment with its
mounting hardware off the gearbox.
Fuel
Your engine requires a mixture of
gasoline and engine oil.
WARNING
For health reasons, avoid direct skin
contact with gasoline and avoid inhaling
gasoline vapor.
STIHL MotoMix
STIHL recommends the use of STIHL
MotoMix. This ready-to-use fuel mix
contains no benzol or lead, has a high
octane rating and ensures that you
always use the right mix ratio.
STIHL MotoMix uses STIHL HP Ultra
two-stroke engine oil for an extra long
engine life.
MotoMix is not available in all markets.
Mixing Fuel
NOTICE
Unsuitable fuels or lubricants or mix
ratios other than those specified may
result in serious damage to the engine.
Poor quality gasoline or engine oil may
damage the engine, sealing rings, hoses
and the fuel tank.
Gasoline
Use only high-quality brand-name
gasoline with a minimum octane rating
of 90 – leaded or unleaded.
Gasoline with an ethanol content of
more than 10% can cause running
problems in engines with a manually
adjustable carburetor and should not be
used in such engines.
Engines equipped with M-Tronic deliver
full power when run on gasoline with an
ethanol content of up to 25% (E25).
Engine Oil
If you mix the fuel yourself, use only
STIHL two-stroke engine oil or another
high-performance engine oil in
accordance with JASO FB, JASO FC,
JASO FD, ISO-L-EGB, ISO-L-EGC or
ISO-L-EGD.
STIHL specifies STIHL HP Ultra twostroke engine oil or an equivalent highperformance engine oil in order to
maintain emission limits over the
machine’s service life.
Mix Ratio
STIHL 50:1 two-stroke engine oil: 50
parts gasoline to 1 part oil
Examples
Gasoline STIHL engine oil 50:1
Liters Liters (ml)
1 0.02 (20)
5 0.10 (100)
10 0.20 (200)
15 0.30 (300)
20 0.40 (400)
25 0.50 (500)
N Use a canister approved for storing
fuel. Pour oil into canister first, then
add gasoline and mix thoroughly.
22
FS 400, FS 450
English
256BA060 KN
250BA051 KN
Storing Fuel
Store fuel only in approved safety-type
fuel canisters in a dry, cool and safe
location protected from light and the sun.
Fuel mix ages – only mix sufficient fuel
for a few weeks work. Do not store fuel
mix for longer than 30 days. Exposure to
light, the sun, low or high temperatures
can quickly make the fuel mix unusable.
STIHL MotoMix may be stored for up to
2 years without any problems.
N Thoroughly shake the mixture in the
canister before fueling your
machine.
WARNING
Pressure may build up in the canister –
open it carefully.
N Clean the fuel tank and canister
from time to time.
Dispose of remaining fuel and cleaning
fluid properly in accordance with local
regulations and environmental
requirements.
Fueling
Preparations
N Open the filler cap.
N Fill up with fuel.
N Close the filler cap.
WARNING
After fueling, tighten down the filler cap
as securely as possible by hand.
Changing the Fuel Pickup Body
FS 400, FS 450
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.
Filling Up with Fuel
Take care not to spill fuel while fueling
and do not overfill the tank. STIHL
recommends you use the STIHL filler
nozzle for fuel (special accessory).
Change the fuel pickup body every year:
N Drain the fuel tank.
N Use a hook to pull the fuel pickup
body out of the tank and take it off
the hose.
N Push the new pickup body into the
hose.
N Place the pickup body in the tank.
23
English
2
3
1
002BA240 KN
256BA016 KN
256BA017 KN
3
STOP
56
4
7
002BA182 KN
1
2
START
STOP-
Fitting the Full Harness
N Put on the full harness (1).
N Adjust the length of the strap so that
the spring hook (2) is about a hand’s
width below your right hip. Overlong ends of straps may be
shortened after completing the
adjustment.
N Attach the spring hook to the
machine's perforated strip (3).
Find the right attachment point for the
cutting attachment you are using – see
"Balancing the Brushcutter".
Balancing the Machine
The unit is balanced differently,
depending on the cutting attachment
used.
N With the unit suspended from the
harness, see how it is balanced and
change attachment point as
necessary:
Mowing attachments
Mowing heads, grass cutting blades and
brush knives and shredder blades
should just touch the ground.
Circular saw blades
Circular saw blades should "hover"
about 20 cm above the ground.
Starting / Stopping the
Engine
Control Handle
Controls
1 Throttle trigger lockout
2 Throttle trigger
3 Slide control
Positions of slide control
4STOP-0 – engine off – ignition is
switched off
5 F – normal run position – the engine
is running or can start
6START – ignition is switched on –
the engine can start
24
FS 400, FS 450
English
250BA018 KN
9
8
256BA094 KN
002BA038 KN
002BA040 KN
Symbol on slide control
7 h – stop symbol and arrow. To stop
the engine, push the slide control in
the direction of the arrow on the stop
symbol (h) to STOP-0.
Starting
N Press down the trigger lockout lever
and squeeze the throttle trigger
N and hold them in that position.
N Move the slide control to START
and hold it there.
N Now release the throttle trigger,
slide control and trigger lockout in
that order. This is the starting
throttle position.
N Set the choke knob (8)
g if the engine is cold
e for warm start – also use this posi-
tion if the engine has been running
but is still cold.
N Press the manual fuel pump
bulb (9) at least five times – even if
the bulb is filled with fuel.
Cranking
N Press in the decompression valve
button for each starting attempt.
N Place the unit on the ground: It must
rest securely on the engine support
and the deflector. Check that the
cutting attachment is not touching
the ground or any other obstacles.
N Make sure you have a safe and
secure footing.
N Hold the unit firmly on the ground
with your left hand and press down
– do not touch the throttle trigger or
lockout lever – your thumb should
be under the fan housing.
NOTICE
Do not stand or kneel on the drive tube.
FS 400, FS 450
25
English
002BA072 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 Turn the choke knob to e.
N Press in button to open the
decompression valve.
N Continue cranking until the engine
runs.
As soon as the engine runs
N Blip the throttle trigger immediately.
The slide control moves to the
normal run position F – and the
engine settles down to idle speed.
WARNING
Make sure the carburetor is correctly
adjusted. The cutting attachment must
not rotate when the engine is idling.
The machine is now ready for operation.
Shut off the engine.
N Push the slide control in the
direction of the arrow on the stop
symbol (h) to STOP-0.
At very low outside temperatures
As soon as the engine runs:
N Blip the throttle trigger to disengage
the starting throttle position. The
slide control moves to the normal
run position F – and the engine
settles down to idle speed.
N Open the throttle slightly.
N Warm up the engine for a short
period.
FS 400, 450: Change over to winter
mode if necessary – see section on
"Winter Operation".
If engine does not start
Choke knob
If you did not turn the choke knob to e
quickly enough after the engine began to
fire, the combustion chamber is flooded.
N Turn the choke knob to e.
N Select the starting throttle position.
N Start the engine by pulling the
starter rope briskly – 10 to 20 pulls
may be necessary.
If the engine still does not start
N Move the slide control to STOP-0.
N Remove the spark plug – see
"Spark Plug".
N Dry the spark plug.
N Open the throttle wide and hold it
that position.
N Crank the engine several times with
the starter to clear the combustion
chamber.
N Refit the spark plug – see "Spark
Plug".
N Move the slide control to START.
N Set the choke knob to e – even if
the engine is cold.
N Start the engine.
Throttle cable adjustment
N Check adjustment of throttle cable –
see chapter on "Adjusting the
Throttle Cable".
Fuel tank run until completely dry
N After refueling, press the manual
fuel pump bulb at least five times –
even if the bulb is filled with fuel.
N Set the choke knob according to
engine temperature.
N Start the engine.
26
FS 400, FS 450
English
1
2
3
256BA074 KN
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 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 Turn the choke knob to g.
N Loosen the screw (1).
N Remove the filter cover (2).
N Clean away loose dirt from around
the filter and inside the filter cover.
N Remove and check the filter
element (3) – replace if dirty or
damaged.
N Install the filter element in the filter
cover.
N Refit the filter cover.
Adjusting the Carburetor
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 Mount the cutting attachment.
N Check the air filter and clean or
replace if necessary.
N Check that the throttle cable is
properly adjusted – readjust if
necessary – see chapter on
"Adjusting the Throttle Cable".
FS 400, FS 450
27
English
255BA001 KN
LA
1
L
H
3/4
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 until it is against
its seat, then turn it back 1 full turn
Adjusting 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)
clockwise until the engine runs
smoothly – the cutting attachment
must not rotate.
Cutting attachment rotates when engine
is idling
N Turn the idle speed screw (LA)
counterclockwise until the cutting
attachment stops moving and then
turn the screw another 1/2 to 1 full
turn in the same direction.
WARNING
If the cutting attachment continues to
rotate when the engine is idling, have
your machine checked and repaired by
your servicing dealer.
Erratic idling behavior, poor acceleration
(despite correction to setting of LA
screw).
Idle setting is too lean
N Turn the low speed screw (L)
carefully counterclockwise, no
further than stop, until the engine
runs and accelerates smoothly.
Erratic idling behavior
Idle setting is too rich
N Turn the low speed screw (L)
carefully clockwise, no further than
stop, until the engine runs smoothly
and still accelerates satisfactorily.
It is usually necessary to change the
setting of the idle speed screw (LA) after
every correction to the low speed
screw (L).
Fine Tuning for Operation at High
Altitude
A slight correction of the setting may be
necessary if engine does not run
satisfactorily:
N Carry out the standard setting.
N Warm up the engine.
N Turn high speed screw (H) slightly
clockwise (leaner) – no further than
stop.
NOTICE
After returning from high altitude, reset
the carburetor to the standard setting.
If the setting is too lean there is a risk of
engine damage due to insufficient
lubrication and overheating.
28
FS 400, FS 450
English
256BA047 KN
3
1
2
256BA048 KN
1
2
3
256BA076 KN
Winter Operation
Mount the "Intake Air Preheating Kit"
4128 007 1001 (special accessory) to
reduce the risk of air filter and carburetor
icing.
At temperatures below +10°C, in
powdery or drifting snow
N Remove the standard air filter (1)
and install the special filter (2) for
winter operation.
N Push the cover (3) up against the
underside of the filter cover. This is
the winter position.
At temperatures above +10°C
N Remove the special air filter (2) for
winter operation and install the
standard filter (1) in its place.
N Push the cover (3) into the summer
position.
Electric Handle Heating
Switching on the handle heating
(depending on model)
N Move the switch in the left handle to
Z – move the switch back to 0 to turn
off the heating.
If the handle temperature feels too high
– move the switch to 0.
There is no risk of overheating during
long periods of operation. The heating
system is maintenance-free. Contact
your dealer if you have any problems.
STIHL recommends a STIHL servicing
dealer.
FS 400, FS 450
29
English
4902BA033 KN
000BA039 KN
A
1
000BA045 KN
Spark Plug
N If the engine is down on power,
difficult to start or runs poorly at idle
speed, first check the spark plug.
N Fit a new spark plug after about 100
operating hours – or sooner if the
electrodes are badly eroded. Install
only suppressed spark plugs of the
type approved by STIHL – see
"Specifications".
Removing the Spark Plug
N Move the slide control to STOP-0.
Checking the Spark Plug
N Clean dirty spark plug.
N Check electrode gap (A) and
readjust if necessary – see
"Specifications".
N Rectify the problems which have
caused fouling of the spark plug.
Possible causes are:
– Too much oil in fuel mix.
– Dirty air filter.
– Unfavorable running conditions.
N Use resistor type spark plugs with a
properly tightened adapter nut.
Installing the spark plug
N Screw home the spark plug, fit the
boot and press it down firmly.
N Remove the spark plug boot (1).
N Unscrew the spark plug.
30
WARNING
Arcing may occur if the adapter nut (1) is
loose or missing. Working in an easily
combustible or explosive atmosphere
may cause a fire or an explosion. This
can result result in serious injuries or
damage to property.
FS 400, FS 450
English
1
2
256BA044 KN
Engine Running Behavior Lubricating the Gearbox
If engine running behavior is
unsatisfactory even though the air filter
is clean and the carburetor and throttle
cable are properly adjusted, the cause
may be the muffler.
Have the muffler checked by a servicing
dealer for contamination
(carbonization).
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer.
Use STIHL gear lubricant (special
accessory) for lubrication.
N Check grease level about every 100
hours of operation.
N Unscrew the filler plug (1). If no
grease can be seen on the inside of
the filler plug, screw the tube of
lubricant (2) into the filler hole.
N Squeeze up to 5 g grease into the
gearbox.
Storing the Machine
For periods of about 3 months or longer
N Drain and clean the fuel tank in a
well ventilated area.
N Dispose of fuel properly in
accordance with local
environmental requirements.
N Run the engine until the carburetor
is dry – this helps prevent the
carburetor diaphragms sticking
together.
N Remove, clean and inspect the
cutting attachment. Coat metal
cutting attachments with corrosion
inhibitor.
N Thoroughly clean the machine – pay
special attention to the cylinder fins
and air filter.
N Store the machine in a dry and
secure location – out of the reach of
children and other unauthorized
persons.
FS 400, FS 450
NOTICE
Do not completely fill the gearbox with
grease.
N Refit the filler plug and tighten it
down firmly.
31
English
2
1
002BA083 KN
2
1
2
2
1
1
002BA406 KN
Sharpening Metal Cutting
Blades
N Use a sharpening file (see "Special
Accessories") to sharpen dull
cutting attachments. In case of
more serious wear or nicks:
Resharpen with a grinder or have
the work done by a dealer – STIHL
recommends a STIHL servicing
dealer.
N Sharpen frequently, take away as
little metal as possible – two or three
strokes of the file are usually
enough.
Balancing
N After resharpening about 5 times,
check the cutting attachment for
out-of-balance on a STIHL balancer
– see “Special Accessories” – or
have it checked by a dealer and re-
balanced as necessary – STIHL
recommends a STIHL servicing
dealer.
Maintaining the Mowing
Head
Placing power tool on the ground
N Shut off the engine.
N Lay your power tool on its back so
that the cutting attachment
mounting face is pointing up.
Replacing Nylon Line
Always check the mowing head for signs
of wear before replacing the nylon line.
N Resharpen the teeth (1) uniformly –
do not alter the contour of the parent
blade (2) in any way.
See cutting attachment packaging for
additional sharpening instructions. Keep
the packaging for future reference.
32
WARNING
If there are signs of serious wear,
replace the complete mowing head.
The nylon mowing line is referred to as
"nylon line" or "line" in the following.
The mowing head is supplied with
illustrated instructions for replacing the
nylon line. Keep the instructions for the
mowing head in a safe place.
N If necessary, remove the mowing
head.
FS 400, FS 450
English
Adjusting Nylon Line
STIHL SuperCut
Fresh line is advanced automatically if
the remaining line is at least 6 cm
(2 1/2 in) long. The blade on the
deflector trims overlong lines to the
correct length.
STIHL AutoCut
N With the engine running, hold the
rotating mowing head above the
grass surface.
N Tap it on the ground once – fresh
line is advanced and the blade on
the deflector trims it to the right
length.
Fresh line is advanced every time the
mowing head is tapped on the ground.
For this reason observe the mowing
head's cutting performance during
operation. If the mowing head is tapped
on the ground too often, the line limiting
blade will unnecessarily cut off unused
lengths of nylon line.
Line feed operates only if both lines are
still at least 2.5 cm (1 in) long.
STIHL TrimCut
WARNING
To reduce the risk of injury, always shut
off the engine before adjusting the nylon
line by hand.
N Pull the spool up – rotate it about 1/6
turn counterclockwise until it
engages – and allow it to spring
back.
N Pull ends of the lines outward.
Repeat the above procedure as
necessary until both lines reach the
limiter blade on the deflector.
Rotating the spool from one stop to the
next advances about 4 cm (1 1/2 in) of
fresh line.
Replacing Nylon Line
STIHL PolyCut
Precut lengths of nylon line can be fitted
to the PolyCut in place of the cutting
blades.
STIHL DuroCut, STIHL PolyCut
WARNING
To reduce the risk of injury, always shut
off the engine before refilling the mowing
head.
N Fit precut lengths of nylon line in the
mowing head as described in the
instructions supplied.
Replacing Cutting Blades
STIHL PolyCut
Always check the mowing head for signs
of wear before installing new cutting
blades.
WARNING
If there are signs of serious wear,
replace the complete mowing head.
The thermoplastic cutting blades are
referred to as "blades" in the following.
The mowing head is supplied with
illustrated instructions for replacing the
blades. Keep the instructions for the
mowing head in a safe place.
WARNING
To reduce the risk of injury, always shut
off the engine before installing the
blades.
N Remove the mowing head.
N Replace blades as shown in the
illustrated instructions.
N Mount the mowing head on the
machine.
FS 400, FS 450
33
English
Maintenance and Care
The following intervals apply to normal operating conditions only. If your daily working time is longer or operating conditions are difficult (very dusty work area, etc.),
shorten the specified intervals accordingly.
before starting work
after finishing work or daily
after each refueling stop
weekly
monthly
every 12 months
if problem
if damaged
as required
Complete machine
Control handle Check operation XX
Air filter
Manual fuel pump (if fitted)
Pickup body in fuel tank
Fuel tank Clean XXX
Carburetor
Spark plug
Cooling inlets
Spark arrestor
All accessible screws and nuts (not adjusting screws)
Antivibration elements
2)
in muffler
Visual inspection (condition, leaks) X X
Clean X
Clean XX
Replace X
Check X
Have repaired by servicing dealer
Check X
Replace XXX
Check idle adjustment – the cutting
attachment must not rotate
Adjust idle speed X
Readjust electrode gap X
Replace after every 100 operating hours
Visual inspection X
Clean X
Have checked by servicing dealer
Have cleaned or replaced by servicing
1)
dealer
Retighten X
Check XXX
Have replaced by servicing dealer
1)
1)
1)
X
XX
XX
X
X
34
FS 400, FS 450
English
The following intervals apply to normal operating conditions only. If your daily working time is longer or operating conditions are difficult (very dusty work area, etc.),
shorten the specified intervals accordingly.
before starting work
after finishing work or daily
after each refueling stop
weekly
monthly
every 12 months
if problem
if damaged
as required
Visual inspection XX
Cutting attachment
Metal cutting attachment Sharpen XX
Gearbox lubrication
Safety labels Replace X
1)
STIHL recommends an authorized STIHL servicing dealer.
2)
not in all versions, market-specific
Replace X
Check tightness XX
Check XXX
Replenish X
FS 400, FS 450
35
English
Minimize Wear and Avoid
Damage
Observing the instructions in this manual
helps reduce the risk of unnecessary
wear and damage to the power tool.
The power tool must be operated,
maintained and stored with the due care
and attention described in this owner's
manual.
The user is responsible for all damage
caused by non-observance of the safety
precautions, operating and maintenance
instructions in this manual. This includes
in particular:
– Alterations or modifications to the
product not approved by STIHL.
– Using tools or accessories which
are neither approved or suitable for
the product or are of a poor quality.
– Using the product for purposes for
which it was not designed.
– Using the product for sports or
competitive events.
– Consequential damage caused by
continuing to use the product with
defective components.
Maintenance Work
All the operations described in the
"Maintenance Chart" must be performed
on a regular basis. If these maintenance
operations cannot be performed by the
owner, they should be performed by a
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer. STIHL dealers are
regularly given the opportunity to attend
training courses and are supplied with
the necessary technical information.
If these maintenance operations are not
carried out as specified, the user
assumes responsibility for any damage
that may occur. Among other parts, this
includes:
– Damage to the engine due to
neglect or deficient maintenance
(e.g. air and fuel filters), incorrect
carburetor adjustment or
inadequate cleaning of cooling air
inlets (intake ports, cylinder fins).
– Corrosion and other consequential
damage resulting from improper
storage.
– Damage to the machine resulting
from the use of poor quality
replacement parts.
Parts Subject to Wear and Tear
Some parts of the power tool are subject
to normal wear and tear even during
regular operation in accordance with
instructions and, depending on the type
and duration of use, have to be replaced
in good time. Among other parts, this
includes:
– Cutting attachments (all types)
– Mounting hardware for cutting
attachments (rider plate, nut, etc.)
– Deflectors for cutting attachments
– Clutch
– Filters (air, fuel)
– Rewind starter
– Spark plug
– Antivibration elements
36
FS 400, FS 450
Main Parts
2
4
1
3
5
6
7
8
9
10
11
16
12
13
14
15
17
18
256BA097 KN
#
English
1 Handlebar
2 Switch for handle heating (option)
3 Throttle trigger
4 Slide control
5 Throttle trigger lockout
6 Clamp screw
7 Carrying strip
8 Manual fuel pump
9 Choke knob
10 Filter cover
11 Fuel tank
12 Spark plug boot
13 Decompression valve
14 Muffler
15 Starter grip
16 Carburetor adjusting screw
17 Tank cap
18 Guard plate
# Serial number
FS 400, FS 450
37
English
5
2
002BA359 KN
1
3
3
6
4
1
4
8
7
002BA361 KN
002BA362 KN
10
9
Specifications
Engine
STIHL single cylinder two-stroke engine
FS 400
7 Shredder blade
8 Shredder deflector (for shredder
blade only)
9 Circular saw blade
10 Limit stop for circular saw blades
only
Displacement: 40.2 cc
Bore: 40 mm
Stroke: 32 mm
Engine power to
ISO 8893:
Idle speed: 2,800 rpm
Cut-off speed (rated): 12,500 rpm
Max. output shaft
speed (cutting
attachment)
FS 400: 8,930 rpm
FS 400 with long
shaft: 8,930 rpm
FS 400 with short
shaft: 8,750 rpm
1.9 kW (2.6 bhp)
at 9,000 rpm
1 Mowing head
2 Deflector for mowing heads only
3 Blade
4 Deflector for all mowing
attachments
5 Skirt
6 Metal mowing attachment
38
FS 450
Displacement: 44.3 cc
Bore: 42 mm
Stroke: 32 mm
Engine power to
ISO 8893:
Idle speed: 2,800 rpm
Cut-off speed (rated): 12,500 rpm
Max. output shaft
speed (cutting
attachment):
2.1 kW (2.9 bhp)
at 9,000 rpm
FS 400, FS 450
English
FS 450: 8,930 rpm
FS 450 with long
shaft: 8,930 rpm
FS 450 with short
shaft: 8,750 rpm
Ignition System
Electronic magneto ignition
Spark plug (resistor
type):
Bosch WSR 6 F,
NGK BPMR 7 A
Electrode gap: 0.5 mm
Fuel System
All position diaphragm carburetor with
integral fuel pump
Fuel tank capacity:
FS 400: 670 cc (0.67 l)
FS 450: 670 cc (0.67 l)
Weight
Dry, without cutting attachment and
deflector
FS 400: 8.0 kg
FS 400 with short shaft: 8.1 kg
FS 450: 8.0 kg
FS 450 with short shaft: 8.1 kg
FS 450 with long shaft: 8.1 kg
Overall length
without cutting attachment
FS 400: 1765 mm
FS 400 with short shaft: 1635 mm
FS 450: 1765 mm
FS 450 with short shaft: 1635 mm
FS 450 with long shaft: 1825 mm
Noise and Vibration Data
Noise and vibration data measurements
on FS units include idling and rated
maximum speed with the same duration
of exposure.
For further details on compliance with
Vibration Directive 2002/44/EC see
www.stihl.com/vib.
Sound pressure level L
to ISO 22868
peq
with mowing head
FS 400: 99 dB(A)
FS 450: 99 dB(A)
with metal mowing
attachment
FS 400: 97 dB(A)
FS 450: 99 dB(A)
Sound power level L
to ISO 22868
weq
with mowing head
FS 400: 112 dB(A)
FS 450: 113 dB(A)
with metal mowing
attachment
FS 400: 110 dB(A)
FS 450: 111 dB(A)
Vibration measurement a
hv,eq
to
ISO 22867
with mowing
head
FS 400: 2.5 m/s
FS 450: 3.0 m/s23.0 m/s
with metal mowing attachment
FS 400: 2.1 m/s
FS 450: 3.6 m/s22.6 m/s
Handle,
left
Handle,
left
2
2
Handle,
right
2.5 m/s
Handle,
right
2.4 m/s
2
2
2
2
The K-factor in accordance with
Directive 2006/42/EC is 2.0 dB(A) for
the sound pressure level and sound
power level; the K-factor in accordance
with Directive 2006/42/EC is 2.0 m/s
2
for the vibration level.
REACH
REACH is an EC regulation and stands
for the Registration, Evaluation,
Authorisation and Restriction of
Chemical substances.
For information on compliance with the
REACH regulation (EC) No. 1907/2006
see www.stihl.com/reach.
Exhaust Emissions
The CO
value measured in the EU type
2
approval procedure is specified at
www.stihl.com/co2.
The measured CO
value was
2
determined on a representative engine
in accordance with a standardized test
procedure under laboratory conditions
and does not represent either an explicit
or implied guarantee of the performance
of a specific engine.
FS 400, FS 450
39
English
000BA073 KN
The applicable exhaust emission
requirements are fulfilled by the
intended usage and maintenance
described in this instruction manual. The
type approval expires if the engine is
modified in any way.
Maintenance and Repairs Disposal
Users of this machine may only carry out
the maintenance and service work
described in this user manual. All other
repairs must be carried out by a
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer. STIHL dealers are
regularly given the opportunity to attend
training courses and are supplied with
the necessary technical information.
When repairing the machine, only use
replacement parts which have been
approved by STIHL for this power tool or
are technically identical. Only use highquality replacement parts in order to
avoid the risk of accidents and damage
to the machine.
STIHL recommends the use of original
STIHL replacement parts.
Original STIHL parts can be identified by
the STIHL part number, the {
logo and the STIHL parts symbol K
(the symbol may appear alone on small
parts).
Observe all country-specific waste
disposal rules and regulations.
STIHL products must not be thrown in
the garbage can. Take the product,
accessories and packaging to an
approved disposal site for environmentfriendly recycling.
Contact your STIHL servicing dealer for
the latest information on waste disposal.
40
FS 400, FS 450
English
EC Declaration of Conformity
ANDREAS STIHL AG & Co. KG
Badstr. 115
D-71336 Waiblingen
Germany
declare in exclusive responsibility that
the product
Category: Clearing saw
Make: STIHL
Model: FS 400
FS 400 K
FS 450
FS 450 K
FS 450 L
Serial identification: 4128
Displacement
all FS 400: 40.2 cc
all FS 450: 44.3 cc
conforms to the provisions of Directives
2011/65/EU, 2006/42/EC, 2014/30/EU
and 2000/14/EC and has been
developed and manufactured in
compliance with the following standards
in the versions valid at the time of
production:
EN ISO 11806-1, EN 55012,
EN 61000-6-1
The measured and guaranteed sound
power levels were determined according
to Directive 2000/14/EC, Annex V, using
the ISO 10884 standard.
Measured sound power level
Guaranteed sound power level
all FS 400: 114 dB(A)
all FS 450: 115 dB(A)
Technical documents deposited at:
ANDREAS STIHL AG & Co. KG
Produktzulassung (Product Licensing)
The year of manufacture and serial
number are applied to the product.
Done at Waiblingen, 28.10.2019
ANDREAS STIHL AG & Co. KG
Thomas Elsner
Director Product Management and
Services
all FS 400: 112 dB(A)
all FS 450: 113 dB(A)
FS 400, FS 450
41
0458-255-0121-B
englisch
G
www.stihl.com
*04582550121B*
0458-255-0121-B
Loading...