STIHL HS 45
Instruction Manual
Notice d’emploi
G Instruction Manual
1 - 23
F Notice d’emploi
24 - 51
Contents
English
Guide to Using this Manual 2
Safety Precautions and Working
Techniques 2
Using the Unit 8
Fuel 9
Fueling 10
Starting / Stopping the Engine 10
Operating Instructions 12
Original Instruction ManualPrinted on chlorine-free paper
Cleaning the Air Filter 12
Engine Management 13
Adjusting the Carburetor 13
Spark Plug 14
Engine Running Behavior 15
Lubricating the Gearbox 15
Storing the Machine 16
Sharpening Instructions 16
Inspections and Maintenance by
Dealer 16
Maintenance and Care 17
Main Parts 19
Specifications 20
Maintenance and Repairs 21
Printing inks contain vegetable oils, paper can be recycled.
Disposal 21
STIHL Limited Emission Control
Warranty Statement 22
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
0458-253-8221-B. VA2.F20.
0000006578_009_GB
HS 45
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 manual fuel
pump
Filler hole for gear
lubricant
Blade lock
Rotating handle
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
Special safety precau
tions must be observed
when working with this
power tool because it has
very sharp, high-speed
cutting blades.
It is important you read
and understand the User
Manual before commis
sioning and keep it in a
safe place for future ref
erence. Non-compliance
with the User Manual
may cause serious 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 are not allowed to work with the
power tool – except adolescents above
16 years of age who are instructed
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.
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HS 45
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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 understands the
information contained in this manual.
The use of machines that emit noise
may be limited to certain hours of the
day as specified by national and/or
regional or local regulations.
Anyone operating the machine must be
well rested, 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. 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.
Anyone who has consumed alcohol or
drugs or medicines affecting their ability
to react must not operate a power tool.
Use the machine only for cutting
hedges, shrubs, bushes, scrub and the
like. The machine must not be used for
any other purposes – risk of accidents!
Other uses are not permitted and may
lead to accidents or 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 blades and accessories
that are explicitly approved for this
power tool 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 accidents
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.
Clothing and equipment
Wear proper protective clothing and
equipment.
Clothing must be sturdy
but allow complete free
dom 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.
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WARNING
To reduce the risk of eye
injuries, wear close-fit
ting safety glasses in
accordance with Euro
pean Standard EN 166.
Make sure the safety
glasses are a snug fit.
Wear "personal" sound protection, e.g.
ear defenders.
Wear sturdy protective
gloves made of a resist
ant material (e. g.
leather).
STIHL can supply a comprehensive
range of personal protective equipment.
Transporting the machine
Always stop the engine.
Attach the blade scabbard even when
carrying the machine over short
distances.
Carry the power tool by the handle –
cutting blades behind you. Do not touch
hot parts of the machine, especially the
muffler and gear housing – risk of burns!
By vehicle: When transporting in a
vehicle, properly secure your machine to
prevent turnover, damage and fuel
spillage.
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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.
The power tools may be fitted as
standard with different fuel caps.
After fueling, tighten
down the screw-type fuel
cap as securely as
possible.
Place the clip lock fuel
cap (bayonet-type) in
position, turn it until it will
go no further and fold the
clip lock down.
This helps reduce the risk of unit
vibrations causing 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!
Before starting
Check that your power tool is properly
assembled 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
– Insert the blade lock (if fitted)
– Slide control / stop switch must
move easily to STOP or 0
– Smooth action of throttle trigger
lockout 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
sparking that could ignite
combustible fumes and cause a fire!
– Cutting blades must be properly
tightened and in safe operating
condition (clean, sharp, not bent or
warped), correctly mounted and
thoroughly sprayed with STIHL
resin solvent (lubricant)
– Check cutter guard (if fitted) for
damage
– 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
To reduce the risk of personal injury, do
not operate your power tool if it is
damaged or not properly assembled!
Starting the engine
Start the engine at least 3 meters from
the fueling spot, outdoors only.
Place the power tool on firm ground in
an open area. Make sure you have good
balance and secure footing. Hold the
power tool securely. The cutting blades
must be clear of the ground and all other
obstructions because they may begin to
run when the engine starts.
Your power tool is designed to be
operated by one person only. Do not
allow other persons in the work area –
even when starting.
Avoid contact with the cutting blades –
risk of injury!
Do not drop-start the engine – start it as
described in the User Manual.
Note that the cutting blades continue to
run for a short period after you let go of
the throttle trigger - flywheel effect!
Check engine idling: The cutting blades
must remain at a standstill when the
engine idles – throttle trigger released.
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Holding and guiding the machine
Always hold the unit firmly with both
hands on the handles. Wrap your fingers
and thumbs around the handles.
Right-handed users
Right hand on the control handle and left
hand on the handlebar.
Left-handed users
Left hand on the control handle and right
hand on the handlebar.
Make sure you always have a good
footing and hold the machine so that the
cutting blades are always facing away
from your body.
While working
In the event of impending danger or in
an emergency, switch off the engine
immediately – move the slide control /
stop switch to 0 or STOP.
Ensure that there are no bystanders
within the working area.
Watch the cutting blades at all times – do
not cut areas of the hedge that you
cannot see.
Be extremely careful when cutting tall
hedges, check the other side of the
hedge before starting work.
Check for correct idling, so that the
cutting blades stop moving when the
throttle trigger is released.
If the cutting blades still move, have the
machine repaired by your specialist
dealer. Check and correct the idle speed
setting at regular intervals.
Note that the cutting blades continue to
run for a short period after you let go of
the throttle trigger - flywheel effect!
The gearhead becomes hot during
operation. To reduce the risk of burn
injury, do not touch the gear housing!
Take special care in slippery and wet
conditions, in snow, on slopes or uneven
ground, etc. – risk of slipping!
Clear away fallen branches, scrub and
cuttings.
Watch out for obstacles: tree stumps,
roots – risk of tripping or stumbling!
Make sure you always have good
balance and secure footing.
When working at heights:
– Always use a lift bucket
– Never use the machine while
standing on a ladder or in a tree
– Never work on an insecure support
– Never use the machine with just one
hand
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 feeling 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. These
gases may be odorless
and invisible and may
contain unburned hydro
carbons and benzene.
Never run the engine
indoors or in poorly venti
lated 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.
Stop work immediately if you start
suffering from nausea, headaches,
impaired vision (e.g. your field of vision
gets smaller), impaired hearing,
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HS 45
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English
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. Combustible fuel vapor may
escape from the fuel system.
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 controlled in this position.
Inspect the hedge and work area to
avoid damaging the cutting blades:
– Remove stones, rocks, pieces of
metal and other solid objects
– Ensure that no sand or small stones
get between the cutting blades, e.g.
when working close to the ground.
– When cutting hedges next to or
against wire fences, do not touch
wire with the cutting blades
Do not touch electric power lines – never
cut through electric power lines – risk of
electrocution!
Do not touch the cutting
blades.while the engine
is running. If the cutting
blades become jammed
by an object, switch off
the engine immediately
before attempting to
remove the object – risk
of injury!
Opening the throttle when the cutting
blades are jammed increases the load
and reduces the working speed of the
engine. The clutch then slips
continuously and this causes
overheating and damage to important
components (e.g. clutch, plastic housing
components) – as a result, there is a risk
of injury! from the idling cutting blades
If the hedge is very dusty or dirty, spray
the cutting blades with STIHL resin
solvent from time to time during cutting.
This will significantly reduce blade
friction, the aggressive effects of sap
and the build-up of dirt particles.
The dust which is generated during
operation may be harmful to health.
Wear a dust mask in case of dust
formation.
Before you leave the machine: Shut the
engine off.
Check the cutting blades at regular short
intervals during operation or
immediately if there is a noticeable
change in cutting behavior:
– Shut off the engine
– Wait for cutting blades to come to a
standstill
– Check the condition and firm seat,
watch out for fine cracks
– Ensure that the cutting blades are
sharp
Always clean plant residue, chips,
leaves and excess lubricant off the
engine and muffler – risk of fire!
After finishing work
Always clean dust and dirt off the
machine – do not use any grease
solvents for this purpose.
Spray the cutting blades with STIHL
resin solvent. Run the motor briefly so
that the solvent is evenly distributed.
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
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HS 45
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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.
Maintenance, replacement, or repair of
the emission control devices and
systems may be performed by any
nonroad engine repair establishment or
individual. However, if you make a
warranty claim for a component which
has not been serviced or maintained
properly, STIHL may deny coverage.
For any maintenance please refer to the
maintenance chart and to the warranty
statement near the end of the instruction
manual.
HS 45
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English
Using the Unit
Cutting Season
Observe country-specific or municipal
rules and regulations for cutting hedges.
Do not use your power tool during other
people's normal rest periods.
Cutting Sequence
Use lopping shears or a chain saw to cut
out thick branches first.
Cut both sides of the hedge first, then
the top.
Disposal
Do not throw cuttings in the garbage can
– they can be composted!
Working Technique
Vertical Cut
Swing the cutting blade from the bottom
upwards in an arc – lower the nose of the
blade, move along the hedge and then
swing the blade up again in an arc.
Any working position above head height
is tiring. To minimize the risk of
accidents, work in such positions for
short periods only.
Horizontal Cut
Hold the cutter bar at an angle of 0° to
10° as you swing the hedge trimmer
horizontally.
Swing the cutting blade in an arc
towards the outside of the hedge so that
the cuttings are swept to the ground.
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Fuel
This engine is certified to operate on
unleaded gasoline and with the mix ratio
50:1.
Your engine requires a mixture of highquality premium gasoline and highquality 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.
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 aircooled engine oils for mixing.
We recommend STIHL 50:1 two-stroke
engine oil since it is specially formulated
for use in STIHL engines.
To ensure the maximum performance of
your STIHL engine, use a high quality 2cycle engine oil. To help your engine run
cleaner and reduce harmful carbon
deposits, STIHL recommends using
STIHL HP Ultra 2-cycle engine oil or ask
your dealer for an equivalent fully
synthetic 2-cycle engine oil.
To meet the requirements of EPA and
CARB we recommend to use STIHL HP
Ultra oil.
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 30 days of storage.
Store in approved safety fuel-canisters
only. When mixing, pour oil into the
canister first, and then add gasoline.
Examples
Gasoline Oil (STIHL 50:1 or equiva
lent high-quality oils)
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)
Dispose of empty mixing-oil canisters
only at authorized disposal locations.
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253BA001 KN
4
3
2
1
253BA020 KN
5
6
253BA021 KN
253BA022 KN
Fueling
Preparations
N Before fueling, clean the filler cap
and the area around it to ensure that
no dirt falls into the tank.
N Position the machine so that the
filler cap is facing up.
N Open the filler cap.
Fill 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).
WARNING
After fueling, tighten down the filler cap
as securely as possible by hand.
10
Starting / Stopping the
Engine
N Observe safety precautions – see
chapter on "Safety Precautions and
Working Techniques".
N Move the stop switch (1) to I.
N Press down the lockout lever (2)
and squeeze the throttle trigger (3)
– hold both levers in that position.
N Press in the starting throttle lock (4).
N Let go of the lockout lever, throttle
trigger and starting throttle lock.
This is the starting throttle position.
N Set the choke lever (5) to
l if the engine is cold
j 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 (6) at least five times – even if
the bulb is filled with fuel.
Cranking
N Place the unit on the ground.
N Remove the blade scabbard. Check
that the cutting blades are not
touching the ground or any other
obstacles.
N Make sure you have a safe and
secure footing.
N Hold the unit firmly with your left
hand on the front handle and press
down.
N Pull the starter grip slowly with your
right hand 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
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so that the starter rope can rewind
properly.
HS 45
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6
253BA023 KN
If the engine is cold (choke set to l)
N Pull the starter rope five times.
N Set choke lever to j and
N continue cranking until the engine
runs.
If conditions are unfavorable and the
engine does not start after 10 pulls with
the choke lever set to j :
N Set choke to l and pull starter
rope five times. Set choke to j and
continue cranking.
If the engine is warm (choke set to j)
N Continue cranking until the engine
runs.
As Soon as Engine Runs
N Blip the throttle trigger – the engine
settles down to idle speed.
If the engine stops during warm-up or
acceleration
N Repeat the starting procedure as
described under "If the engine is
cold".
Other Hints on Starting
If the engine does not start
N Make sure all settings are correct
(choke shutter, throttle trigger in
starting throttle position, stop switch
to I).
N Repeat the starting procedure.
If the engine still does not start
N Remove the spark plug – see
"Spark Plug".
N Dry the spark plug.
N Open the throttle wide.
N Crank the engine several times with
the starter to clear the combustion
chamber.
N Install the spark plug – see "Spark
Plug".
N Move the stop switch to I.
N Set choke lever to j – even if the
engine is cold.
N Now start the engine.
If fuel tank has been run completely dry
and then refueled
N Press the manual fuel pump
bulb (6) at least five times – even if
the bulb is filled with fuel.
N Now start the engine.
WARNING
Make sure the carburetor is correctly
adjusted. The cutting blades must not
move when the engine is idling.
Your machine is now ready for
operation.
Stopping the Engine
N Move the stop switch to O.
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253BA008 KN
1
2
5
2
3
253BA024 KN
4
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 Move the choke lever to l.
N Press in the tab (1) and swing the
filter cover (2) down.
N Clean away loose dirt from around
the filter.
N Remove the foam element (3) and
felt element (4).
N Wash the foam element in a clean,
non-flammable solution (e.g. soapy
water) and then dry.
N Fit a new felt element. As a
temporary measure you can knock it
out on the palm of your hand or blow
it out with compressed air. Do not
wash.
N Replace any damaged parts.
N Fit the foam element (3) in the filter
cover (2) and the felt element (4) in
the filter housing (5).
N Close the filter cover so that it snaps
into position.
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253BA018 KN
H
L
LA
253BA016 KN
L
Engine Management Adjusting the Carburetor
Exhaust emissions are controlled by the
design of the engine and components
(e.g. carburation, ignition, timing and
valve or port timing).
General Information
The carburetor comes from the factory
with a standard setting.
This setting provides an optimum fuel-air
mixture under most operating
conditions.
Preparations
N Shut off the engine.
N Check the air filter and clean or
replace if necessary.
N Inspect cutting blades and clean if
necessary (clean, move freely, not
warped).
Standard Setting
Adjusting Idle Speed
N Carry out the standard setting.
N Start and warm up the engine.
N Adjust idle speed with the idle speed
screw (LA) so that the cutting
blades do not run.
Engine stops while idling
N Turn the idle speed screw (LA)
slowly clockwise until the engine
runs smoothly – the cutting blades
must not run.
Cutting blades run when engine is idling
N Turn the idle speed screw (LA)
counterclockwise until the cutting
blades stop moving – then turn it
another 1/2 to 1 turn in the same
direction.
HS 45
N Turn high speed screw (H)
counterclockwise as far as stop (no
more than 3/4 turn).
N Turn the low speed screw (L)
clockwise as far as stop, then turn it
back 3/4 turn.
WARNING
If the cutting blades continue moving
when the engine is idling, have your
power tool checked and repaired by your
servicing dealer.
Erratic idling behavior, poor acceleration
(despite correction to setting of LA
screw).
Idle setting is too lean
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English
253BA030 ST
000BA039 KN
A
1
000BA045 KN
N Turn the low speed screw (L) slowly
counterclockwise until the engine
runs and accelerates smoothly.
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.
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 stop switch to O.
N Pull off the spark plug boot.
N Unscrew the spark plug.
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.
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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.
HS 45
English
1
2
253BA025 KN
N Use resistor type spark plugs with a
properly tightened adapter nut.
Installing the spark plug
N Fit the spark plug by hand and
screw it in
N Tighten spark plug with combination
wrench
N Press the spark plug boot firmly
onto the spark plug
Engine Running Behavior Lubricating the Gearbox
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 (carbonization) by your
servicing dealer.
STIHL recommends that you have
servicing and repair work carried out
exclusively by an authorized STIHL
servicing dealer.
Use STIHL gear lubricant for hedge
trimmers (special accessory) to lubricate
the blade drive gear.
After about 50 hours of operation:
N Remove the screw plug (1) from the
gearbox.
N Screw the tube of grease (2) into the
filler hole.
N Squeeze up to 5 g grease into the
gearbox.
HS 45
NOTICE
Do not completely fill the gearbox with
grease.
N Remove the tube of grease (2).
N Refit the filler plug and tighten it
down firmly.
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