Stihl FS 45 User manual

STIHL FS 45
Instruction Manual2 - 25

Contents
1 Guide to Using this Manual.........................2
2 Safety Precautions and Working Techni‐
ques............................................................ 2
3 Approved Combinations of Cutting Attach‐
ment, Deflector, Handle and Harness.........9
4 Mounting the Loop Handle..........................9
5 Mounting the Deflector..............................11
6 Mounting the Cutting Attachment..............11
7 Fuel........................................................... 13
8 Fueling...................................................... 14
9 Starting / Stopping the Engine.................. 15
10 Operating Instructions...............................17
11 Cleaning the Air Filter............................... 18
12 Adjusting the Carburetor........................... 18
13 Spark Plug................................................ 19
14 Engine Running Behavior......................... 20
15 Storing the Machine.................................. 20
16 Maintaining the Mowing Head...................20
17 Inspections and Maintenance by Dealer...21
18 Maintenance and Care..............................22
19 Minimize Wear and Avoid Damage...........23
20 Main Parts.................................................23
21 Specifications............................................24
22 Maintenance and Repairs......................... 24
23 Disposal.................................................... 25
24 EC Declaration of Conformity................... 25
Dear Customer,
Thank you for choosing a quality engineered
STIHL product.
It has been built using modern production techni‐
ques and comprehensive quality assurance.
Every effort has been made to ensure your satis‐
faction 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
1 Guide to Using this Manual
1.1 Pictograms
The meanings of the pictograms attached to the
machine are explained in this manual.
Depending on the model concerned, the follow‐
ing 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
1.2 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.
1.3 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 man‐
ual.
2 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.
English
2 0458-232-0121-F
© ANDREAS STIHL AG & Co. KG 2021
0458-232-0121-F. VA0.F21.
Printed on chlorine-free paper Printing inks contain vegetable oils, paper can be recycled.
Original Instruction Manual 0000000049_028_GB

It is important you read and under‐
stand the User Manual before com‐
missioning and keep it in a safe place
for future reference. Non-compliance
with the User Manual may cause seri‐
ous or even fatal injury.
Observe all applicable local safety regulations,
e.g. by trade organizations, social insurance
institutions, labor safety authorities etc.
If you have never used a power tool before:
Have your dealer or other experienced user
show you how to operate your machine – or
attend a special course to learn how to operate
it.
Minors should never be allowed to use the
machine – except for apprentices over the age of
16 when working under supervision.
Children, animals and bystanders must not be
allowed near the machine.
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.
The user is responsible for accidents or risks
involving third parties or their property.
Do not lend or rent your power tool without the
User Manual. Be sure that anyone using it under‐
stands the information contained in this manual.
The use of machines that emit noise may be limi‐
ted to certain hours of the day as specified by
national and/or regional or local regulations.
Anyone operating the machine must be well res‐
ted, in good physical health and in good mental
condition.
If you have any condition that might be aggrava‐
ted 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. This field may interfere with
some pacemakers. STIHL recommends that per‐
sons with pacemakers consult their physician
and the pacemaker manufacturer to reduce any
health risk.
Anyone who has consumed alcohol or drugs or
medicines affecting their ability to react must not
operate a power tool.
Depending on the cutting attachment fitted, use
your trimmer only for cutting grass, wild growth
and similar materials.
The power tool must not be used for any other
purpose because of the increased risk of acci‐
dents and damage to the machine. Never
attempt to modify your power tool in any way
since this may result in accidents or damage to
the machine.
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
your dealer. Use only high quality parts and
accessories. in order to avoid the risk of acci‐
dents and damage to the machine.
STIHL recommends the use of original 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 high-pressure washer to clean the
power tool. The solid jet of water may damage
parts of the unit.
The guard provided with your machine may not
protect the operator from all foreign objects
(gravel, glass, wire etc.) ejected by the revolving
cutting attachment. Ejected objects may also ric‐
ochet and strike the operator.
2.1 Clothing and equipment
Wear proper protective clothing and equipment.
Clothing must be sturdy but allow
complete freedom of movement.
Wear close-fitting clothes such as a
boiler suit, not a loose jacket.
Do not wear clothing which could
become trapped in wood, brush or
moving parts of the machine. Do not
wear a scarf, necktie or jewelry. Tie
up and confine long hair above your
shoulders.
Wear sturdy shoes with non-slip
soles.
WARNING
To reduce the risk of eye injuries,
wear close-fitting safety glasses in
accordance with European Standard
EN 166. Make sure the safety
glasses are a snug fit.
2 Safety Precautions and Working Techniques English
0458-232-0121-F 3

Wear face protection and make sure it is a good
fit. Face protection alone is not sufficient to pro‐
tect the eyes.
Wear "personal" sound protection, e.g. ear
defenders.
Wear sturdy protective gloves made
of a resistant material (e. g. leather).
STIHL can supply a comprehensive range of per‐
sonal protective equipment.
2.2 Transporting the machine
234BA001 KN
Always stop the engine.
Carry the unit properly balanced by the shaft or
loop handle.
By vehicle: When transporting in a vehicle, prop‐
erly secure your machine to prevent turnover,
damage and fuel spillage.
2.3 Refueling
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.
Only refuel the machine in a well ventilated
place. If fuel has been spilled, immediately clean
the machine – do not allow your clothes to be
splashed with fuel. If that happens, change your
clothes at once.
After refueling, close the fuel cap as
tightly as possible.
This helps reduce the risk of unit vibrations caus‐
ing an incorrectly tightened fuel cap to loosen or
come off and spill quantities of fuel.
Check for leaks. Do not start the engine if there
is a fuel leak – serious or fatal burns could result!
2.4 Before starting
Check that your power tool is properly assem‐
bled and in good condition – refer to appropriate
chapters in the User Manual:
–Check the fuel system for leaks, especially the
visible parts, e. g., fuel cap, hose connections,
manual fuel pump (only in machines with a
manual fuel pump). In case of leakage and
damage, do not start the engine – risk of fire!
Have the machine serviced by a dealer before
using it
–Use only an approved combination of cutting
attachment, deflector, handle and harness. All
parts must be assembled properly and
securely. To reduce the risk of injury, never
use metal cutting attachments!
–Slide control / stop switch must move easily to
STOP or 0
–Throttle trigger lockout (if installed) and throttle
trigger must move easily – the throttle trigger
must return to the idle position automatically
–Check that the spark plug boot is secure – a
loose boot may cause sparking that could
ignite combustible fumes and cause a fire!
–Check cutting attachment for correct and
secure assembly and good condition
–Check safety devices (e. g., deflector for cut‐
ting attachments) for damage and/or wear.
Always replace damaged parts. Never operate
the unit with a damaged deflector
–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 the harness and handle(s) to suit your
height and reach
To reduce the risk of personal injury, do not
operate your power tool if it is damaged or not
properly assembled!
To prepare for emergencies when using a har‐
ness: Practice setting down the machine quickly.
To avoid damage, do not throw the machine to
the ground when practicing.
English 2 Safety Precautions and Working Techniques
4 0458-232-0121-F

2.5 Starting the engine
Start the engine at least 3 meters from the fuel‐
ing 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 ejected objects, do not
allow other persons within a radius of 15 meters
of your own position – even when starting.
Avoid contact with the cutting attach‐
ment – risk of injury!
Do not drop-start the engine – start it as descri‐
bed in the User Manual.
The cutting attachment runs on for a
short while after releasing the throttle
trigger – coasting effect!
Check engine idling: The cutting attachment
must remain at a standstill when the engine idles
– throttle trigger released.
To reduce the risk of fire, keep hot exhaust
gases and hot muffler away from easily combus‐
tible materials (e.g. wood chips, bark, dry grass,
fuel).
2.6 Holding and guiding the
machine
Always hold the unit firmly with both hands on
the handles.
Make sure you always have good balance and
secure footing.
002BA056 KN
Left hand on the loop handle, right hand on the
shaft handle, even if you are left-handed.
2.7 While working
In the event of impending danger or in an emer‐
gency, switch off the engine immediately - move
the slide control/stop switch to STOP or 0.
15m (50ft)
The cutting attachment may catch and eject
objects over a great distance and cause injury -
therefore, do not allow any other persons within
a radius of 15 meters of your own position. This
distance must also be maintained in relation to
objects (vehicles, window panes) – risk of prop‐
erty damage! Even at a distance over 15 m, dan‐
ger cannot be ruled out.
Check that the engine is properly idling so that
the cutting tool will not continue rotating after you
release the throttle trigger.
Check and correct the idle speed setting at regu‐
lar intervals. If the cutting attachment still rotates
at idle speed, have your dealer make proper
adjustments or repairs.
Take special care in slippery conditions – damp,
snow, ice, on slopes or uneven ground.
Watch out for obstacles: tree stumps, roots – risk
of tripping or stumbling!
Make sure you always have good balance and
secure footing.
Only work while standing on the ground, never
on a ladder or mobile elevated work platform.
Be particularly alert and cautious when wearing
hearing protection because your ability to hear
warnings (shouts, alarms, etc.) is restricted.
Take breaks when you start getting tired or feel‐
ing fatigue – risk of accidents!
Work calmly and carefully – in daylight conditions
and only when visibility is good. Proceed with
caution, do not put others in danger.
As soon as the engine is running, the
power machine generates toxic
exhaust gas.As soon as the engine is
running, the power machine gener‐
ates toxic exhaust gas. These gases
may be odorless and invisible and
may contain unburned hydrocarbons
and benzene. Never run the engine
indoors or in poorly ventilated loca‐
2 Safety Precautions and Working Techniques English
0458-232-0121-F 5

tions, 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 con‐
fined locations. This reduces the risk of serious
or fatal injury from breathing toxic fumes.
Stop work immediately if you start suffering from
nausea, headaches, impaired vision (e.g. your
field of vision gets smaller), impaired hearing,
dizziness, or impaired concentration – these
symptoms may possibly be the result of too-high
exhaust gas concentration – Risk of accidents!
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. Com‐
bustible fuel vapor may escape from the fuel sys‐
tem.
Dusts, mist and fumes emissions during the work
may be hazardous to your health. Wear respira‐
tory protection in case of heavy dust or smoke
emission.
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 in particular that the fuel system has no
leaks and the safety equipment is fully operative.
Never use a power tool that is no longer safe to
operate. In case of doubt, contact a dealer.
Do not operate your power tool in the starting
throttle position – engine speed cannot be con‐
trolled in this position.
Never work without protection suita‐
ble for the respective machine and
cutting tool – risk of injury by ejected
objects!
Check the work site – rocks, metal
objects etc. may be caught up and
ejected – possibly over a distance of
15 m – risk of injury! – They can also
damage the cutting attachment and
other property (e. g. parking vehicles,
windows).
Be particularly careful when working on difficult,
densely grown terrain.
When mowing in high shrubbery, under shrub‐
bery and hedges: Hold the cutting tool at a work‐
ing height of at least 15 cm – avoid risks to ani‐
mals.
Before you leave the machine: Shut the engine
off.
Check the cutting tool regularly at short intervals,
and immediately if you feel a change in its
behavior:
–Turn off the engine, hold the device securely,
press the cutting attachment against the
ground to stop it
–Check the condition and firm seat, watch out
for fine cracks
–Immediately replace defective cutting tools,
also in case of minor hairline 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!
Do not continue using or attempt to repair dam‐
aged or cracked cutting attachments by welding,
straightening or modifying the shape (out of bal‐
ance).
Particles or pieces may come off and hit the
operator or a bystander at a high speed – risk of
most severe injuries!
If a rotating cutting attachment touches a rock or
another hard object, sparks may be generated
which may possibly ignite combustible materials.
Also dried-out plants and brushwood are com‐
bustible, above all in hot and dry weather. If
there is a risk of fire, do not use cutting attach‐
ments in the vicinity of combustible materials,
dried-out plants or brushwood. It is mandatory
that you ask the responsible forestry office about
the current fire hazard.
2.7.1 When using mowing heads
Only use the protection with properly mounted
blade to ensure that the mowing line is restricted
to the permissible length.
Always switch off the engine to adjust the mow‐
ing line for manually adjustable mowing heads –
risk of injury!
Misuse with mowing lines that are too long
reduces the working speed of the engine. The
constant slipping of the clutch causes overheat‐
ing and damage to important components (e. g.
clutch, plastic housing parts) – e. g. due to the
English 2 Safety Precautions and Working Techniques
6 0458-232-0121-F

cutting attachment rotating during idling – risk of
injury!
2.8 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 cir‐
culation (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.
2.9 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 per‐
formed by a servicing dealer.
STIHL recommends that you have servicing and
repair work carried out exclusively by an author‐
ized 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, 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 inter‐
vals.
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 con‐
dition, 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.
2.10 Cutting Attachments and
Deflectors
For safety reasons only the combinations of cut‐
ting attachment, deflector, handle and shoulder
strap approved in the model-specific instruction
manual may be used.
Only mowing heads may be used on trimmers
with a curved drive tube and loop handle.
2.10.1 Symbols on Deflectors
An arrow shows the direction of rotation of the
cutting attachments.
2 Safety Precautions and Working Techniques English
0458-232-0121-F 7

2.11 Mowing Head with Nylon Lines
000BA019 KN
Nylon line achieves a soft cut for edging and
trimming around fence posts, trees, etc. – less
risk of damaging tree bark.
WARNING
To reduce the risk of injury, never use steel wire
in place of the nylon cutting line.
2.12 STIHL PolyCut 6-3 Mowing
Head with Polymer Blades
1
002BA073 KN
2
002BA074 KN
For mowing unobstructed edges of meadows
(without posts, fences, trees or similar obsta‐
cles).
It is important to follow the maintenance instruc‐
tions for the Polycut mowing head.
Check the wear limit marks!
Wear limit marks are integrated in the base of
the PolyCut.
Do not continue using the PolyCut 6-3 if one of
the circular holes (1; arrow) becomes visible or if
the projecting rim (2; arrow) has worn away.
Install a new mowing head.
WARNING
If the wear limit marks are ignored, there is a risk
of the cutting tool shattering and flying parts
injuring the operator or bystanders.
To reduce the risk of accidents from shattered
blades, avoid contact with stones, metal and sim‐
ilar solid objects.
Check PolyCut blades for cracks at regular inter‐
vals. If a crack is found in one of the blades,
always replace all the blades.
English 2 Safety Precautions and Working Techniques
8 0458-232-0121-F

3 Approved Combinations of Cutting Attachment, Deflector, Han‐
dle and Harness
Cutting attachment Deflector Handle Carrying strap
0000-GXX-0401-A4
1
67
5
2
34
3.1 Permissible combinations
Choose the correct combination from the table
depending on the cutting tool!
WARNING
For safety reasons no other combinations are
permitted – risk of accidents!
3.2 Cutting attachments
3.2.1 Mowing heads
1 STIHL AutoCut C 6-2
2 STIHL DuroCut 5-2
3 STIHL PolyCut 7-3
4 STIHL PolyCut 6-2
3.3 Deflector
5 Guard with blade for mowing heads
3.4 Handle
6 Loop handle
3.5 Carrying strap
7 Shoulder strap can be used
4 Mounting the Loop Handle
The loop handle comes in two different versions.
4.1 Version A
223BA017 KN
223BA018 KN
► Place the friction liner in the loop handle.
3 Approved Combinations of Cutting Attachment, Deflector, Handle and Harness English
0458-232-0121-F 9

4
65
232BA027 KN
1
2
3
A
► Fit the loop handle (1) on the drive tube at dis‐
tance (A) of about 20 cm (8 in.) from the con‐
trol handle (2).
► Slide the spacer (3) – if supplied – into the
loop handle as far as stop.
► Insert the screw (4) through the loop handle
and the spacer until the screw head locates in
the loop handle's hexagon recess.
► Fit the washer (5).
► Screw on the star knob (6) and tighten it down
firmly.
Adjusting loop handle to most comfortable posi‐
tion
► Loosen the star knob (6).
► Move the loop handle (1) along the drive tube
as required.
► Tighten down the star knob (6) firmly.
4.2 Version B
Your new power tool comes with the loop handle
mounted on the drive tube, but it must be turned
and lined up to suit your requirements.
Line up the loop handle.
1
239BA008 KN
► Use the combination wrench to loosen the
screw (1).
239BA009 KN
► Turn the handle to the vertical position.
234BA026 KN
A
The loop handle can be adjusted to suit the
height and reach of the operator and the applica‐
tion by changing distance (A).
Recommendation: distance (A): about 15 cm
(6 in)
English 4 Mounting the Loop Handle
10 0458-232-0121-F

► Slide the handle to the required position.
► Tighten down the screw with the combination
wrench so that the handle cannot be rotated
on the drive tube.
5 Mounting the Deflector
1
2
232BA066 KN
► Push the deflector (1) over the clamp (2) as far
as stop.
4
232BA067 KN
3
► Insert the nut (3) in the hex recess in the
deflector – make sure the holes line up.
► Insert the screw (4) and tighten it down firmly.
6 Mounting the Cutting
Attachment
6.1 Placing power tool on the
ground
546BA016 KN
► Switch off the engine.
► Lay your trimmer on its back with the loop
handle and shroud pointing down and the out‐
put shaft facing up.
6.2 Thrust Plate
232BA033 KN
1
2
3
4
The thrust plate (1) is shipped with the Duro‐
Cut 5‑2 and PolyCut 6‑3. It is only required for
these mowing heads.
STIHL AutoCut 5-2 mowing head, STIHL Auto‐
Cut C 5-2 mowing head
► Pull the thrust plate (1), if fitted, off the shaft
(2).
STIHL PolyCut 5‑2 mowing head, STIHL Fix‐
Cut 6‑3 mowing head
► Slip the thrust plate (1) over the shaft (2) and
engage the hex recess (3) on the external
hexagon (4).
5 Mounting the Deflector English
0458-232-0121-F 11

6.3 Blocking the Shaft
6
6
546BA017 KN
5
► To block the shaft, insert a suitable tool (5)
through the holes (6) in the deflector and
thrust plate – turn the thrust plate back and
forth if necessary.
6.4 Fitting the mowing head with
screw mounting
Keep the supplement sheet for the mowing head
in a safe place.
1
002BA385 KN
► Fit the thrust plate
► Screw the mowing head counterclockwise on
to the shaft (1) as far as it will go
► Retain the shaft
► Tighten the mowing head
NOTICE
Remove the tool that was used to block the
shaft.
6.5 Removing the Mowing Head
► Retain the shaft
► Turn the mowing head counterclockwise
6.6 Fitting Mowing Head without
Screw Mounting
Keep the supplement sheet for the mowing head
in a safe place!
English 6 Mounting the Cutting Attachment
12 0458-232-0121-F

6.6.1 STIHL AutoCut C 6-2
0000-GXX-3937-A0
2
1
3
4
► Place the mowing head (2) on the shaft (3)
while inserting the internal hexagon (2) on the
hexagon (4)
► Hold the mowing head (2) with your hand.
► Turn cap (1) clockwise and tighten it firmly by
hand.
6.6.2 STIHL PolyCut 6-2, PolyCut 7-3
11
5
681BA019 KN
10
► Push thrust plate onto the shaft
► Insert the nut (10) into the mowing head
► Turn the mowing head (11) clockwise until it
engages the shaft (5)
► Retaining the Shaft
► Tighten the mowing head
WARNING
Nuts that move too easily must be replaced.
NOTICE
Remove the tool that was used to block the
shaft.
6.7 Removing the Mowing Head
6.7.1 STIHL AutoCut
► Hold the spool housing steady
► Unscrew the cap counterclockwise.
6.7.2 STIHL PolyCut
► Retaining the Shaft
► Turn the mowing head counterclockwise
7 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.
7.1 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.
7 Fuel English
0458-232-0121-F 13

7.2 Mixing Fuel
NOTICE
Unsuitable fuels or lubricants or mix ratios other
than those specified may result in serious dam‐
age to the engine. Poor quality gasoline or
engine oil may damage the engine, sealing rings,
hoses and the fuel tank.
7.2.1 Gasoline
Use only high-quality brand-name gasoline with
a minimum octane rating of 90 – leaded or unlea‐
ded.
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 con‐
tent of up to 25% (E25).
7.2.2 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 two-stroke
engine oil or an equivalent high-performance
engine oil in order to maintain emission limits
over the machine’s service life.
7.2.3 Mix Ratio
STIHL 50:1 two-stroke engine oil: 50 parts gaso‐
line to 1 part oil
7.2.4 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)
► Use a canister approved for storing fuel. Pour
oil into canister first, then add gasoline and
mix thoroughly.
7.3 Storing Fuel
Store fuel only in approved safety-type fuel can‐
isters 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.
► Thoroughly shake the mixture in the canister
before fueling your machine.
WARNING
Pressure may build up in the canister – open it
carefully.
► 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.
8 Fueling
232BA046 KN
► Before fueling, clean the filler cap and the area
around it to ensure that no dirt falls into the
tank.
► Position the machine so that the filler cap is
facing up.
► Open the filler cap.
Take care not to spill fuel while fueling and do
not overfill the tank. STIHL recommends you use
the STIHL filler nozzle (special accessory).
English 8 Fueling
14 0458-232-0121-F

WARNING
After fueling, tighten down the filler cap as
securely as possible by hand.
9 Starting / Stopping the
Engine
9.1 Controls
2
232BA080 KN
16 7
54
3
1 Stop switch
2 Throttle trigger lockout
3 Throttle trigger
4 Tongue of throttle trigger
5 Catch
9.1.1 Positions of stop switch
6 Run I
7 Stop 0
9.2 Starting
233BA047 KN
4
► Move the stop switch to I.
► Press down the throttle trigger lockout and
hold it there.
► Squeeze the throttle trigger until the catch on
the tongue (4) can be engaged on the housing
(arrow).
► Now release the throttle trigger, tongue and
trigger lockout in that order. This is the starting
throttle position.
9 Starting / Stopping the Engine English
0458-232-0121-F 15

9
8
232BA011 KN
► Set the choke lever (8) to
gif the engine is cold
efor warm start – also use this position if the
engine has been running but is still cold.
► Press the manual fuel pump bulb (9) at least
five times – even if the bulb is filled with fuel.
9.2.1 Cranking
232BA012 KN
232TI013 KN
► Put the unit on the ground: It must rest
securely on the engine support and the deflec‐
tor. Check that the cutting attachment is not
touching the ground or any other obstacles.
► Make sure you have a firm footing.
► Hold the unit with your left hand and press it
down firmly – your thumb should be under the
fan housing.
NOTICE
Do not stand or kneel on the drive tube.
232BA014 KN
► Hold the starter grip with your right hand.
9.2.2 Version without ErgoStart
► 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.
9.2.3 Version with ErgoStart
► Pull the starter grip slowly until you feel it
engage and then pull it out slowly and steadily.
English 9 Starting / Stopping the Engine
16 0458-232-0121-F

NOTICE
Do not pull out the starter rope all the way – it
might otherwise break.
9.2.4 Both versions
► Do not let the starter grip snap back. Guide it
slowly back into the housing so that the starter
rope can rewind properly.
► Continue cranking.
9.2.5 When engine begins to fire
8
232TI015 KN
► After no more than five pulls, move the choke
lever (8) to e and
► continue cranking.
9.2.6 As soon as the engine runs
► Squeeze the throttle trigger to disengage the
tongue – the engine will settle down to idle
speed.
WARNING
Make sure the carburetor is correctly adjusted.
The cutting attachment must not rotate when the
engine is idling.
Your machine is now ready for operation.
9.3 Stopping the engine
► Move the stop switch to 0.
9.4 If engine does not start
Choke lever
If you did not move the choke lever quickly
enough to e after the engine began to fire, the
engine is flooded.
►Set choke to e and
► Move the stop switch to I, interlock lever and
throttle trigger to the starting throttle position.
► Start the engine by pulling the starter rope
briskly – 10 to 20 pulls may be necessary.
If the engine still does not start
► Move the stop switch to 0.
► Remove the spark plug – see "Spark Plug".
► Dry the spark plug.
► Crank the engine several times with the starter
to clear the combustion chamber.
► Refit the spark plug – see "Spark Plug".
► Move the stop switch to I.
►Set choke to e – even if the engine is cold.
► Now start the engine.
9.4.1 Fuel tank run until completely dry
► After refueling, press the manual fuel pump
bulb at least five times – even if the bulb is fil‐
led with fuel.
► Set the choke knob to suit the engine temper‐
ature.
► Start the engine.
10 Operating Instructions
10.1 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 dur‐
ing 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.
10.2 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 engine-mounted
components (ignition, carburetor) from thermal
overload.
10.3 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-
of-service periods – see "Storing the Machine".
10 Operating Instructions English
0458-232-0121-F 17

11 Cleaning the Air Filter
11.1 If there is a noticeable loss of
engine power
232BA017 KN
1
2
►Set the choke lever to g.
► Press in the tab (1) and swing the filter
cover (2) down.
► Clean away loose dirt from around the filter.
232BA018 KN
4
3
► Remove the felt element (3) from the filter
housing (4) and replace it – knock out or blow
out as a temporary measure – do not wash.
► Replace damaged parts.
► Fit the felt element (3) in the filter housing (4).
► Close the filter cover so that it snaps into posi‐
tion.
12 Adjusting the Carburetor
12.1 General Information
The carburetor comes from the factory with a
standard setting.
This setting provides an optimum fuel-air mixture
under most operating conditions.
12.2 Preparations
► Shut off the engine.
► Mount the cutting attachment.
► Check the air filter and clean or replace if nec‐
essary.
12.3 Standard Setting
L
233BA069 KN
► Turn the high speed screw (H) carefully clock‐
wise until it is against its seat, then turn it back
2 full turns.
► Turn the low speed screw (L) carefully clock‐
wise until it is against its seat, then turn it back
1 1/2 turns.
12.4 Adjusting Idle Speed
► Carry out standard setting.
English 11 Cleaning the Air Filter
18 0458-232-0121-F

► Start and warm up the engine.
12.4.1 Engine stops while idling
► Turn the idle speed screw (LA) slowly clock‐
wise until the engine runs smoothly – the cut‐
ting attachment must not rotate.
12.4.2 Cutting attachment rotates when
engine is idling
► Turn the idle speed screw (LA) counterclock‐
wise 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.
12.4.3 Erratic idling behavior, poor accelera‐
tion (even though setting of LA screw
is correct).
Idle setting is too lean
► Rotate the low speed screw (L) slowly
about 1/4 turn counterclockwise until the
engine runs smoothly and still accelerates sat‐
isfactorily.
12.4.4 Erratic idling behavior
Idle setting is too rich
► Rotate the low speed screw (L) slowly
about 1/4 turn clockwise 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).
12.5 Fine Tuning for Operation at
High Altitude
A slight correction of the setting may be neces‐
sary if the engine does not run satisfactorily:
► Carry out standard setting.
► Warm up the engine.
► Turn high speed screw (H) slightly clockwise
(leaner) – no more than a 3/4 turn.
NOTICE
After returning from high altitude, reset the car‐
buretor to the standard setting.
If the setting is too lean there is a risk of engine
damage due to insufficient lubrication and over‐
heating.
13 Spark Plug
► If the engine is down on power, difficult to start
or runs poorly at idle speed, first check the
spark plug.
► 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 "Specifica‐
tions".
13.1 Removing the Spark Plug
► Move the stop switch to 0.
1
232BA081 KN
► Pull off the spark plug boot (1).
► Unscrew the spark plug.
13.2 Checking the Spark Plug
000BA039 KN
A
► Clean dirty spark plug.
► Check electrode gap (A) and readjust if neces‐
sary – see "Specifications".
► Rectify the problems which have caused foul‐
ing of the spark plug.
Possible causes are:
–Too much oil in fuel mix.
13 Spark Plug English
0458-232-0121-F 19

–Dirty air filter.
–Unfavorable running conditions.
1
000BA045 KN
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 inju‐
ries or damage to property.
► Use resistor type spark plugs with a properly
tightened adapter nut.
13.3 Installing the spark plug
► Screw home the spark plug, fit the boot and
press it down firmly.
14 Engine Running Behavior
If engine running behavior is unsatisfactory even
though the air filter is clean and the carburetor is
properly adjusted, the cause may be the muffler.
Have the muffler checked for contamination (car‐
bonization) by your servicing dealer.
STIHL recommends that you have servicing and
repair work carried out exclusively by an author‐
ized STIHL servicing dealer.
15 Storing the Machine
For periods of about 3 months or longer
► Drain and clean the fuel tank in a well ventila‐
ted area.
► Dispose of fuel properly in accordance with
local environmental requirements.
► Run the engine until the carburetor is dry – this
helps prevent the carburetor diaphragms stick‐
ing together.
► Remove, clean and inspect the cutting attach‐
ment. Coat metal cutting attachments with cor‐
rosion inhibitor.
► Thoroughly clean the machine – pay special
attention to the cylinder fins and air filter.
► Store the machine in a dry and secure location
– out of the reach of children and other unau‐
thorized persons.
16 Maintaining the Mowing
Head
16.1 Placing power tool on the
ground
546BA016 KN
► Switch off the engine.
► Lay your trimmer on its back with the loop
handle and shroud pointing down and the out‐
put shaft facing up.
16.2 Replacing Nylon Line
Always check the mowing head for signs of wear
before replacing the nylon line.
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.
► If necessary, remove the mowing head.
English 14 Engine Running Behavior
20 0458-232-0121-F