Stihl FS 410 C K User manual

{
STIHL FS 410 C K Instruction Manual
Notice d’emploi

GInstruction Manual
1 - 40
FNotice d’emploi
41 - 84

Original Instruction ManualPrinted on chlorine-free paper
Printing inks contain vegetable oils, paper can be recycled.
© ANDREAS STIHL AG & Co. KG, 2012 0458-745-8221-B. VA2.M11. 0000003940_004_GB
FS 410 C K
English
1
{
Contents
Dear Customer,
Thank you for choosing a quality
engineered STIHL product.
This machine has been built using
modern production techniques and
comprehensive quality assurance.
Every effort has been made to ensure
your satisfaction and troublefree use of
the machine.
Please contact your dealer or our sales
company if you have any queries
concerning your machine.
Your
Hans Peter Stihl
Guide to Using this Manual 2
Safety Precautions and Working
Techniques 2
Approved Combinations of Cutting
Attachment, Deflector, Limit Stop
and Harness 9
Mounting the Bike Handle 10
Adjusting the Throttle Cable 12
Mounting the Deflector 13
Mounting the Cutting Attachment 13
Fuel 14
Fueling 15
Fitting the Full Harness 18
Balancing the Trimmer/Brushcutter 18
Starting / Stopping the Engine 18
Operating Instructions 20
Air filter 21
Engine Management 22
Adjusting the Carburetor 22
Winter Operation 22
Spark Plug 24
Engine Running Behavior 25
Replacing the Starter Rope and
Rewind Spring 25
Storing the Machine 29
Sharpening Metal Cutting Blades 29
Inspection and Maintenance by
User 30
Inspections and Maintenance by
Dealer 31
Maintenance and Care 33
Main Parts 35
Specifications 37
Special Accessories 37
Maintenance and Repairs 38
STIHL Limited Emission Control
Warranty Statement 38

FS 410 C K
English
2
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.
Symbols in text
Warning where there is a risk of an
accident or personal injury or serious
damage to property.
Caution where there is a risk of
damaging the machine or its individual
components.
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.
Observe the national safety regulations
issued, for example, by the employers'
liability insurance association, social
security institutions, occupational safety
and health authorities or other
organizations.
If you have never used a power tool
before: Ask the salesperson or another
expert to explain how to use it safely – or
attend a training course.
Minors should never be allowed to use
the machine – except for young trainees
over the age of 16 when working under
supervision.
Children, animals and bystanders must
remain at a distance.
When not using the machine, it must be
laid down in such a way that it does not
endanger anyone. Ensure that the
machine cannot be used without
authorization.
Guide to Using this Manual
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
Safety Precautions and
Working Techniques
Because the machine 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
carefully read the entire
Instruction Manual before
using the machine for the
first time and keep it in a
safe place for future ref-
erence. Non-compliance
with the Instruction Man-
ual may cause serious or
even fatal injury.

FS 410 C K
English
3
The user is responsible for accidents or
risks involving third parties or their
property.
The machine should only be provided or
loaned to people familiar with this model
and its operation. The Instruction
Manual should always be handed over
with the machine.
Use of machines that emit noise may be
restricted in terms of time by national
and/or on-site, local regulations.
The machine may only be operated by
people who are fit, in good physical
health and in good mental condition.
If you have any condition that might be
aggravated by strenuous work, check
with your doctor before operating a
machine.
If you have a pacemaker: The ignition
system of your machine produces an
electromagnetic field of very low
intensity. An effect on individual
pacemaker types cannot be excluded
entirely. STIHL recommends that you
consult your doctor and the
manufacturer of your pacemaker in
order to avoid health hazards.
Anyone who has consumed alcohol,
medicines affecting their ability to react
or drugs must not operate the machine.
The machine may only be used to cut
wild shrubs, shrubs, scrub, bushes,
small trees and the like up to a diameter
of 7 cm.
The machine must not be used for any
other purposes – risk of injury!
Only use cutting attachments or
accessories which have been approved
by STIHL for this machine or which are
technically equivalent. Contact a
servicing dealer if in doubt. Only use
high-quality tools or accessories.
Otherwise there may be a risk of
accidents or damage to the machine.
Only use original STIHL replacement
parts and accessories. These have been
optimized for the product and the user's
requirements.
Never modify the machine in any way,
as this could be extremely dangerous.
STIHL excludes all liability for personal
injury and damage to property caused
while using unauthorized attachments.
Do not use high-pressure cleaners to
clean the machine. The hard water jet
can damage parts of the machine.
The deflector provided with your
machine may not protect the operator
from all foreign objects (gravel, glass,
wire etc.) thrown by the revolving cutting
attachment. Thrown objects may also
ricochet and strike the operator.
Clothing and equipment
Wear proper protective clothing and
equipment.
Clothing which could become trapped in
wood, brush or moving parts of the
machine should not be worn. Do not
wear a scarf, tie or jewelry when
operating the machine. Long hair must
be tied up and covered (headscarf, cap,
helmet, etc.).
Sturdy shoes with non-slip shoes are
permissible only when using mowing
heads.
A face mask alone is not sufficient to
protect the eyes.
Wear "personal" hearing protection – e.
g., ear defenders.
STIHL can supply a comprehensive
range of protective clothing and
equipment.
Clothing must be sturdy
and snug-fitting, but allow
complete freedom of
movement. Wear snug
fitting clothing – an over-
all, not a loose-fitting
jacket.
Wear safety boots with
steel toe caps and non-
slip soles.
Always wear a hard hat
during thinning work, in
high brush, and when-
ever there is a risk of
injury due to falling
objects. Wear a face
shield and always wear
safety glasses – danger
due to flying objects.
Wear sturdy gloves.

FS 410 C K
English
4
Transporting the machine
Always switch off the engine.
Carry the machine hanging on the
harness or by the shaft so that it is
balanced. Protect metal cutting
attachments against touching – use a
transport guard.
In vehicles: Properly secure your
machine to prevent turnover, damage
and fuel spillage.
Refueling
Switch off the engine before refueling.
Never refuel the machine while the
engine is still hot – the fuel may spill over
– risk of fire!
Open the fuel filler cap carefully so that
any excess pressure is relieved
gradually and fuel does not splash out.
The machine may only be refueled in a
well ventilated place. Clean the machine
immediately if fuel is spilled. Change
your clothes immediately if they are
contaminated with fuel.
A number of different filler caps are
installed as standard at the factory.
This helps reduce the risk of engine
vibrations causing an incorrectly
tightened filler cap to loosen or come off
and spill fuel.
Check for leaks. Do not start the engine
if there is a fuel leak – serious or fatal
burns could result.
Before starting
Check that machine is properly
assembled and in good condition – refer
to appropriate chapters in the Instruction
Manual:
–The combination of cutting
attachment, deflector, handle and
harness must be permissible and all
parts must be mounted correctly
–The stop button must be easy to
push
–Check the choke lever, throttle
trigger and throttle trigger lockout
for smooth action - throttle trigger
must return automatically to idle
position. From the choke lever
positions g and <, the choke
lever must return to the run
position F when the throttle trigger
lockout and throttle trigger are
pressed simultaneously
–Check that the spark plug boot is
secure. A loose boot can lead to
flying sparks which may ignite the
escaping fuel/air mixture – risk of
fire!
–Cutting attachment or
interchangeable attachment:
correctly fitted, secure and in
perfect condition.
–Safety devices (e. g., deflector for
cutting attachments, thrust plate) for
damage and/or wear. Replace any
damaged parts. Do not use the
machine with a damaged deflector
or worn thrust plate (if the writing
and arrows are no longer
discernible)
Avoid touching hot parts
of the machine and gear-
box – risk of burns!
Gasoline is an extremely
flammable fuel – keep
clear of naked flames and
fire – do not spill any fuel
– no smoking.
002BA479 KN
Close the filler cap as
tightly as possible after
refueling.
After refueling. place the
cliplock filler cap (bayo-
net-type) in position, turn
it until it will go no further
and fold the cliplock
down.

FS 410 C K
English
5
–Never attempt to modify the controls
or safety devices
–Keep the handles dry and clean –
free from oil and dirt – this is
important for safe control of the
machine
–Adjust carrying harness and
handle(s) in accordance with body
height. To this end, observe the
sections "Fitting the harness" and
"Balancing the machine".
The machine should only be used if it is
in good working order – risk of accident!
To prepare for emergencies when using
a harness: Practice setting down the
machine quickly. In order to avoid
damage, when practicing, do not throw
the machine on the ground.
Starting the engine
Move at least 3 m away from the place
at which the machine was refueled –
never in enclosed spaces.
The machine may only be used on level
ground. Ensure a firm and secure
footing and hold the machine firmly. The
cutting attachment must not touch any
objects and must not touch the ground,
because it may begin to rotate when the
machine is started.
This is a one-person machine – ensure
that there is no-one within 15 meters of
the edger, not even when starting the
power tool! Risk of injury due to thrown
objects!
Check engine idling: The cutting
attachment must remain at a standstill
when the engine idles – throttle trigger
released.
Keep easily combustible materials (e.g.,
wood chips, bark, dry grass, fuel) away
from hot exhaust gases and hot muffler
surfaces – risk of fire!
Holding and guiding the machine
Always hold the machine by the handles
using both hands.
Ensure you always have a firm and safe
footing.
Right hand on the control handle, left
hand on the handlebar grip.
During work
Ensure you always have a firm and safe
footing.
In the event of imminent danger or in an
emergency, push the stop button to stop
the engine.
Ensure that there is no-one within a
15 m radius of the machine – risk of
injury by flying objects! This distance
must also be maintained in relation to
objects (vehicles, window panes) – risk
of property damage!
Check for correct idling, so that the
cutting attachment stops turning when
the throttle trigger is released.
Check and/or correct the idle setting
regularly. Have the machine repaired by
a servicing dealer if the cutting
attachment continues to turn
nevertheless. STIHL recommends
STIHL servicing dealers.
Beware of slipping on ice, water, snow
or uneven ground!
Watch out for obstacles: tree stumps,
roots – risk of stumbling!
Only work while standing on the ground,
never on a ladder, work platform or other
unstable surface.
Avoid contact with the
cutting attachment – risk
of injury!
Do not drop-start the
engine – start as
described in the Instruc-
tion Manual. The blade
runs on for a short while
after releasing the throttle
trigger – coasting effect!
002BA486 KN
15m (50ft)

FS 410 C K
English
6
More care and attention than usual are
required when wearing ear protection –
sounds warning you of impending
danger (shouts, beeps, etc.) cannot be
heard properly.
Take breaks in due time in order to
prevent tiredness and exhaustion – risk
of accidents!
Work calmly and methodically – only
with good lighting and visibility. Take
care not to endanger other people!
Ensure proper ventilation when working
in trenches, hollows or other confined
locations – risk of fatal injury from
breathing toxic fumes!
If you feel sick, if you have a headache,
vision problems (e. g., your field of vision
gets smaller), hearing problems,
dizziness or inability to concentrate, stop
work immediately. Such symptoms may
be caused by an excessively high
concentration of exhaust emissions,
among other things – risk of accident!
Keep the noise and exhaust emissions
to a minimum – do not let the engine run
unnecessarily and only open the throttle
when actually working.
No smoking when working with or near
the machine - risk of fire! Combustible
fuel vapor may escape from the fuel
system.
Dust, fumes and smoke may produced
while working may be hazardous to
health! Wear respiratory protection in
the presence of major dust or smoke.
If the machine 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 - refer also to the
section "Before starting".
Check the fuel system for leaks and
make sure the safety devices are
working properly. Never use the
machine if it is not in good condition.
Consult a servicing dealer if in doubt.
Do not use the machine with the choke
lever in the hot start position < – the
engine speed cannot be controlled in
this setting.
Take particular care when working in
densely overgrown unmanageable
areas.
When mowing in tall brush, bushes and
hedges: Min. 15 cm working height with
the cutting attachment – take care not to
endanger animals.
Always turn off the engine before leaving
the machine unattended!
Examine the cutting attachment
periodically at short intervals and as
soon as you note any noticeable
changes:
–Stop engine, hold machine
securely, allow cutting attachment
to come to a stop
–Check condition and secure fitting;
watch out for cracks
–Ensure that the cutting blades are
sharp
–Replace damaged or blunt cutting
attachments immediately, even in
the event of minor hairline cracks
The tool mount must be cleaned
regularly to remove grass and scrub –
remove blockages on or near the cutting
attachment or deflector.
To change the cutting attachment,
switch off the engine – risk of injury!
Do not reuse or repair damaged or
cracked cutting attachments – for
example, by welding or straightening –
risk of deformation (out-of-balance).
Your power tool produces
toxic exhaust fumes as
soon as the engine is
running. These gases
may be colorless and
odorless and may contain
unburnt hydrocarbons
and benzene. Never use
the machine indoors or in
poorly ventilated areas,
even if your machine is
equipped with a catalytic
converter.
Never work with-
out the
corresponding
deflector for your
machine and cut-
ting attachment –
risk of injury due to
flying objects!
Check terrain: solid
objects, such as stones
or metal parts, etc. can
be hurled aside by the
cutting blade – risk of
injury! They can also
damage the cutting
attachment and other
property (e.g. parking
vehicles, windows).
The gearbox becomes
hot during operation.
Never touch the gearbox
– risk of burns!

FS 410 C K
English
7
Particles or fragments can detach from
the cutting attachment and strike the
operator or other bystanders at high
speed – serious injuries!
Use of metal cutting attachments
STIHL recommends the use of genuine
STIHL metal cutting attachments. Such
parts have been optimized for the
machine and the user's requirements.
Metal cutting attachments turn at high
speed. This results in forces that act on
the machine, the attachment and the
material being cut.
Metal cutting attachments must be
sharpened periodically according to
specifications.
Unevenly sharpened metal cutting
attachments produce imbalances that
can place extreme loads on the machine
– risk of breakage!
Blunt or improperly sharpened edges
can lead to increased loading of the
metal cutting attachment – risk of injury
by cracked or broken parts!
Inspect the metal cutting tool after any
contact with hard objects (e. g., stones,
boulders, metal parts) (e. g., for cracks
and deformations). Burrs and other
visible accumulations of material must
be removed (ideal with a file), because,
during continued operation, they can
come loose at any time and then be
hurled aside – risk of injury!
To reduce the aforementioned risks of
using a metal cutting attachment, the
metal cutting attachment used must
never be excessively large in diameter.
It must not be too heavy. It must be
made from materials of sufficient quality
and have a suitable geometry (shape,
thickness).
A metal cutting attachment not made by
STIHL must not be heavier, thicker,
differently shaped or larger in diameter
than the STIHL metal cutting attachment
approved for this machine – risk of
injury!
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 original
STIHL replacement parts. They are
specifically designed to match your
model and meet your performance
requirements.
To reduce the risk of injury from
unintentional engine startup, always
shut off the engine and disconnect the
spark plug boot before performing any
repairs, maintenance or cleaning work. –
Exception: Carburetor and idle speed
adjustments.
Do not turn the engine over on the
starter with the spark plug boot or spark
plug removed 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.

FS 410 C K
English
8
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.
Maintenance, replacement, or repair of
the emission control devices and
systems may be performed by any
nonroad engine repair establishment or
individual. However, if you make a
warranty claim for a component which
has not been serviced or maintained
properly or if nonapproved replacement
parts were used, STIHL may deny
coverage.
For any maintenance please refer to the
maintenance chart and to the warranty
statement near the end of the instruction
manual.
Symbols on Deflectors
An arrow on the limit stop shows the
correct direction of rotation of the cutting
attachments.
Harness
The harness is included with the
machine or available as a special
accessory.
NUse the harness.
NWith the engine running, attach the
machine to the harness.
Circular saw blades must always be
used in combination with a full harness
with a quick-release system.
Circular Saw Blade
Suitable for cutting shrubs and trees with
a maximum stem diameter of 7 cm.
Before starting the cut, accelerate the
engine up to full throttle. Perform cut
with uniform pressure.
Use circular saw blades only with a
matching limit stop of the correct
diameter.
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.
002BA397 KN
002BA449 KN

FS 410 C K
English
9
Permissible combinations
Choose the proper combination from the
table depending on the cutting
attachment!
For safety reasons only the cutting
attachments and deflectors and/or limit
stops within one line of the table may be
combined with one another. Other
combinations are not permissible – risk
of accident!
Cutting attachments
Metal cutting attachments
1Circular saw blade 200 scratcher
tooth
2Circular saw blade 200 chisel tooth
3Circular saw blade 225 scratcher
tooth
4Circular saw blade 225 chisel tooth
5Circular saw blade 225 (carbide-
tipped)
Circular saw blades of other, non-metal
materials must not be used.
Deflectors / limit stops
6Limit stop for circular saw blades
200
7Limit stop for circular saw blades
225
Harnesses
8Full harness must be used
Approved Combinations of Cutting Attachment, Deflector, Limit Stop and Harness
Cutting attachment Deflector / limit stop Harness
681BA169 KN
126
8
3457

FS 410 C K
English
10
Mounting the bike handle with swiveling
handle support
The machine is supplied with the clamp
moldings (1) mounted to the
handlebar (2).
Mounting the control handle
NTake out the screw (3) and remove
the nut (4) from the control
handle (5).
NLine up the control handle (5)
relative to the handlebar (2): The
throttle trigger (6) must point toward
the gearbox and the clamp
screw (7) toward the engine.
NHolding the control handle (5) in
that position, push it on to the end of
the handlebar (2) and line up the
holes (8).
NFit the nut (4) in the control
handle (5), insert the screw (3) and
tighten it down firmly.
Assembling the handle support
Assembly of the swivelling handle
support involves equipping the clamp
moldings with a spring and mounting
them on the handle support.
Mounting the Bike Handle
21
4BA011 KN
3
4
5
002BA352 KN
7
5
4BA002 KN
6
2
8
6BA019 KN
2
8
3
5
4

FS 410 C K
English
11
NUse the spring (9) from the parts kit
supplied with the machine.
NPlace the spring (9) in the lower
clamp molding (10).
NPosition the clamp moldings (1) with
handlebar (2) on the handle
support (11).
NRaise the grip of the wing screw (7)
to the upright position.
NTurn the wing screw
counterclockwise as far as stop.
NPush the wing screw into the handle
support as far as stop and then
screw it down – but do not finally
tighten yet.
NAdjust the handlebar (2) so that
distance A is no more than 15 cm.
NLine up the handlebar at a right
angle to the drive tube.
NTurn the wing screw clockwise as
far as stop.
NFold the grip of the wing screw down
so that it is flush.
Adjusting the handlebar
Opening the wing screw
NRaise the grip of the wing screw to
the upright position.
NTurn the wing screw
counterclockwise until the handle
support can be moved.
4BA001 KN
9
10
11
1
4BA012 KN
2
A
2
4BA003 KN
7
4BA005 KN
4BA006 KN
4BA013 KN
4BA004 KN

FS 410 C K
English
12
NMove the handlebar to the required
position.
Closing the wing screw
NTurn the wing screw clockwise as
far as stop.
NFold the grip of the wing screw down
so that it is flush.
Swiveling the handlebar
Transport position
NLoosen the wing screw (7) and
unscrew it until the handlebar (2)
can be turned clockwise.
NTurn the handlebar 90° and then
swing the handles down.
NTighten down the wing screw (7)
firmly.
Working position
NReverse the sequence described
above to swing the handles up and
turn the handlebar
counterclockwise.
Correct adjustment of the throttle cable
is a preconditon for correct operation of
the machine in all modes, from starting
to full throttle.
It may be necessary to readjust the
throttle cable after assembling the
machine or after a prolonged period of
operation.
–The throttle cable can checked and
adjusted by the user: see
"Inspection and Maintenance by
User".
–The throttle cable can be checked
and adjusted by your dealer. Have
the machine repaired by your
servicing dealer. STIHL
recommends a STIHL servicing
dealer.
4BA007 KN
4BA005 KN
4BA006 KN
2
7
4BA008 KN
Adjusting the Throttle Cable

FS 410 C K
English
13
Use the Right Deflector
The limit stop is approved only for use
with circular saw blades. It must not be
used in combination with other cutting
attachments.
Mounting the Limit Stop
NRemove dirt from joints on gearbox
and limit stop – make sure that no
dirt gets into the screw holes in the
gearbox.
NPlace the limit stop (1) on the
gearbox (2).
NInsert the screws (3) and tighten
them down firmly.
Preparations
NLay your power tool on its back so
that the cutting attachment
mounting face is pointing up.
Fitting the Thrust Plate
NSlip the thrust plate (1) over the
shaft (2).
Your power tool comes from the factory
with a guard ring (3) and limit stop (4) for
circular saw blades.
The thrust plate (1) on the gearhead is
necessary for mounting circular saw
blades.
Cleaning Gearbox Mounting Hardware
for Cutting Attachment
Check inside of guard ring (3) and area
around it for dirt at regular intervals and
clean if necessary as follows:
NPull the thrust plate (1) off the shaft.
NThoroughly clean the guard ring (3),
shaft (2) and thrust plate (1) – do not
remove the guard ring.
Mounting the Cutting Attachment
Use a limit stop that matches the circular
saw blade – see "Mounting the
Deflector".
Mounting Circular Saw Blades
The cutting edges of circular saw blades
must point clockwise.
A limit stop kit, which includes a limit
stop and a guard ring for circular saw
blades, is available as a special
accessory for mounting circular saw
blades.
Mounting the Deflector
002BA428 KN
002BA429 KN
3
2
1
Mounting the Cutting
Attachment
002BA406 KN
4
002BA430 KN
3
1
2
681BA165 KN

FS 410 C K
English
14
NPlace the circular saw blade (1) in
position.
Collar (a) must locate in the saw blade's
mounting hole (b).
NFit the thrust washer (2) – convex
side must face up.
NFit the rider plate (3).
NBlock the drive shaft.
NScrew on the nut (4)
counterclockwise and tighten it
down firmly.
If the mounting nut turns too freely, fit a
new one.
Remove the tool used to block the shaft.
Removing the Circular Saw Blade
NBlock the drive shaft.
NUnscrew the mounting nut
clockwise.
Remove the tool used to block the shaft.
This engine is certified to operate on
unleaded gasoline and with the mix ratio
50:1.
Your engine requires a mixture of high-
quality premium gasoline and high-
quality two-stroke air-cooled engine oil.
Use premium branded unleaded
gasoline with a minimum octane rating
of 89 (R+M)/2.
Note: Models equipped with a catalytic
converter require unleaded gasoline. A
few tankfuls of leaded gasoline can
reduce the efficiency of the catalytic
converter by more than 50%.
Fuel with a lower octane rating may
result in preignition (causing "pinging")
which is accompanied by an increase in
engine temperature. This, in turn,
increases the risk of the 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 as
well. This could cause running problems
or even damage the engine. For this
reason it is essential that you use only
high-quality fuels!
Fuels with different percentages of
ethanol are being offered. Ethanol can
affect the running behaviour of the
engine and increase the risk of lean
seizure.
2
3
1
4
002BA431 KN
b
a
Fuel

FS 410 C K
English
15
Gasoline with an ethanol content of
more than 10% can cause running
problems and major damage in engines
with a manually adjustable carburetor
and should not be used in such engines.
Engines equipped with M-Tronic can be
run on gasoline with an ethanol content
of up to 25% (E25).
Use only STIHL two-stroke engine oil or
equivalent high-quality two-stroke air-
cooled engine oils for mixing.
We recommend STIHL 50:1 two-stroke
engine oil since it is specially formulated
for use in STIHL engines.
Do not use BIA or TCW (two-stroke
water cooled) mix oils!
Use only STIHL 50:1 heavy-duty engine
oil or an equivalent quality two-stroke
engine oil for the fuel mix in models
equipped with a catalytic converter.
Take care when handling gasoline.
Avoid direct contact with the skin and
avoid inhaling fuel vapour.
The canister should be kept tightly
closed in order to avoid any moisture
getting into the mixture.
The fuel tank and the canister in which
fuel mix is stored should be cleaned
from time to time.
Fuel mix ratio
Only mix sufficient fuel for a few days
work, not to exceed 3 months of storage.
Store in approved safety fuel-canisters
only. When mixing, pour oil into the
canister first, and then add gasoline.
Dispose of empty mixing-oil canisters
only at authorized disposal locations.
Fuel Filler Cap
When fueling on a slope, always position
the machine with the filler cap facing
uphill.
NPlace the machine on level ground
so that the filler cap is facing up.
NBefore fueling, clean the filler cap
and the area around it to ensure that
no dirt falls into the tank.
A number of different filler caps are
installed as standard at the factory.
Threaded filler cap
Examples
Gasoline Oil (STIHL 50:1 or equiva-
lent high-quality oils)
liters liters (ml)
10.02(20)
5 0.10 (100)
10 0.20 (200)
15 0.30 (300)
20 0.40 (400)
25 0.50 (500)
Fueling
2709BA000 KN
2709BA001 KN

FS 410 C K
English
16
Cliplock filler cap (bayonet-type)
Opening screw-type tank cap
NTurn the cap counterclockwise until
it can be removed from the tank
opening.
NRemove the cap.
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).
NFilling up with fuel
Closing screw-type tank cap
NPlace the cap in the opening.
NTurn the cap clockwise as far as
stop and tighten it down as firmly as
possible by hand.
Opening tank cap with hinged grip
NSwing the grip to the upright
position.
NRotate the cap about 1/4 turn
counterclockwise.
NRemove the cap.
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).
NFilling up with fuel
Closing tank cap with hinged grip
Grip must be vertical:
NFit the cap in the opening – the
marks on the cap and filler neck
must line up.
NPress the cap down as far as stop.
2709BA002 KN
2709BA003 KN
2709BA004 KN
2709BA005 KN
2709BA006 KN
2709BA007 KN
2709BA008 KN

FS 410 C K
English
17
NWhile holding the cap depressed,
turn it clockwise until it engages in
position.
NFold the grip flush with the top of the
cap.
Checking tank cap with hinged grip is
properly locked
–The lug on the grip must fully
engage the recess (arrow).
NGrip the cap – it is properly locked if
it cannot be turned or removed.
If tank cap with hinged grip can be
turned or removed
Bottom of cap is twisted in relation to
top:
NPlace the cap on the opening and
rotate it counterclockwise until it
engages the filler neck.
NContinue rotating the cap
counterclockwise (about a quarter
turn) – this causes the bottom of the
cap to be turned to the correct
position.
NTurn and lock the cap clockwise –
see sections on "Closing" and
"Checking security of cap".
2709BA009 KN
2709BA010 KN
2709BA011 KN
Left: Bottom of cap twisted
Right: Bottom of cap correctly
positioned
2709BA012 KN
2709BA013 KN
2709BA014 KN

FS 410 C K
English
18
Fitting the full harness is described in
detail in the instruction sheet supplied.
NPut on the full harness (1).
NAdjust the length of the strap so that
the carabiner (2) is about a hand’s
width below your right hip.
NAttach 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".
NWith the unit suspended from the
harness, see how it is balanced and
change attachment point as
necessary:
Circular Saw Blades
Circular saw blades should "hover"
about 20 cm above the ground.
Throwing off the machine in an
emergency
The machine must be quickly thrown off
in the event of imminent danger.
Practice removing and putting down the
machine as you would in an emergency.
To avoid damage, do not throw the
machine to the ground when practicing.
Operating elements
1Throttle trigger lockout
2Throttle trigger
3Stop switch – with settings for Run
and Stop. To switch off the engine,
the stop switch (…) must be
pressed.
Function of the stop switch and the
ignition
When the stop switch is not actuated, it
is in the position Run: The ignition is
switched on – the engine is ready for
starting and can be started. If the stop
switch is actuated, the ignition is
switched off. Once the engine comes to
a standstill, the ignition is automatically
switched on again.
Fitting the Full Harness
3
002BA411 KN
1
2
Balancing the
Trimmer/Brushcutter
6BA010 KN
Starting / Stopping the
Engine
1
002BA484 KN
2
3