Stihl BR 450 User manual

BR 450, 450 C
Instruction Manual2 - 22

Contents
1 Guide to Using this Manual.........................2
2 Safety Precautions and Working Techni‐
ques............................................................ 2
3 Assembling the Unit.................................... 7
4 Adjusting the Throttle Cable........................9
5 Fitting the Harness......................................9
6 Fuel............................................................. 9
7 Fueling...................................................... 10
8 Information Before You Start.................... 11
9 Starting / Stopping the Engine.................. 11
10 Operating Instructions...............................14
11 Replacing the Air Filter..............................14
12 Adjusting the Carburetor........................... 15
13 Spark Plug................................................ 16
14 Engine Running Behavior......................... 16
15 Storing the Machine.................................. 16
16 Inspections and Maintenance by Dealer...17
17 Maintenance and Care..............................17
18 Minimize Wear and Avoid Damage...........18
19 Main Parts.................................................19
20 Specifications............................................20
21 Maintenance and Repairs......................... 21
22 Disposal.................................................... 21
23 EC Declaration of Conformity................... 21
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 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.
1.2 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.
1.3 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 manual fuel pump
Operate electric starter
2 Safety Precautions and
Working Techniques
Special safety precautions must be
observed when working with a power
tool.
English
2 0458-391-8321-B
© ANDREAS STIHL AG & Co. KG 2022
0458-391-8321-B. VA0.D22.
Printed on chlorine-free paper Printing inks contain vegetable oils, paper can be recycled.
Original Instruction Manual 0000007158_008_GB

It is important that you read the
instruction manual before first use
and keep it in a safe place for future
reference. Non-observance of the
instruction manual may result in seri‐
ous or even fatal injury.
Observe all applicable local safety regulations,
standards and ordinances.
If you have not used this model before: Have
your dealer or other experienced user show you
how it is operated or attend a special course in
its operation.
Minors should never be allowed to use this prod‐
uct.
Keep bystanders, especially children, and ani‐
mals away from the work area.
When the power tool is not in use, put it in a
place where it does not endanger others. Secure
it against unauthorized use.
The user is responsible for avoiding injury to third
parties or damage to their property.
Do not lend or rent your power tool without the
instruction manual. Be sure that anyone using
your power tool understands the information con‐
tained in this manual.
The use of noise emitting power tools may be
restricted to certain times by national or local
regulations.
Do not operate your power tool if any of its com‐
ponents are damaged.
Do not use a pressure washer to clean your
power tool. The solid jet of water may damage
parts of the power tool.
2.1 Accessories and replacement
parts
Only use parts 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 a servicing 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
replacement parts and accessories. They are
specifically designed to match the product and
meet your performance requirements.
Never attempt to modify your machine 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.
2.2 Physical Condition
To operate this power tool you must be rested, in
good physical condition and mental health.
If you have any condition that might be aggrava‐
ted by strenuous work, check with your doctor
before operating a power tool.
Persons with pacemakers only: The ignition sys‐
tem of your power tool produces an electromag‐
netic field of a very low intensity. This field may
interfere with some pacemakers. To reduce
health risks, STIHL recommends that persons
with pacemakers consult their physician and the
pacemaker manufacturer before operating this
power tool.
Do not operate the sprayer if you are under the
influence of any substance (drugs, alcohol)
which might impair vision, dexterity or judgment.
2.3 Intended Use
The blower is designed for blow-sweeping
leaves, grass, paper and similar materials, e.g. in
gardens, sports stadiums, car parks and drive‐
ways. It is also suitable for blow-sweeping forest
paths.
Do not blow-sweep hazardous materials.
Do not use the machine for any other purpose
because of the increased risk of accidents and
damage to the machine. Never attempt to modify
the product in any way since this may result in
accidents or damage to the product.
2.4 Clothing and Equipment
Wear proper protective clothing and equipment.
Clothing must be sturdy but allow
complete freedom of movement.
Wear snug-fitting clothing, an overall
and jacket combination, do not wear
a work coat.
Avoid clothing with loose drawstrings,
laces and ribbons, scarves, neckties,
jewelry or anything that could be
sucked into the air intake in the side
and bottom of the machine. Tie up
and confine long hair so that it cannot
be sucked into the machine.
Wear sturdy shoes with non-slip soles.
2 Safety Precautions and Working Techniques English
0458-391-8321-B 3

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 comfortable and snug
fit.
Wear hearing protection, e.g. earplugs or ear
muffs.
STIHL offers a comprehensive range of personal
protective clothing and equipment.
2.5 Transporting the Power Tool
Always shut off the engine.
Transporting in a vehicle:
–Properly secure your power tool to prevent
turnover, fuel spillage and damage.
2.6 Fueling
Gasoline is an extremely flammable
fuel. Keep clear of naked flames. Do
not spill any fuel – do not smoke.
Always shut off the engine before refueling.
Do not fuel a hot engine – fuel may spill and
cause a fire.
Always remove the power tool from your back
and put it on the ground before refueling. Fuel
the machine only when it is standing on the
ground.
Open the fuel cap carefully to allow any pressure
build-up in the tank to release slowly and avoid
fuel spillage.
Fuel your power tool only in well-ventilated
areas. If you spill fuel, wipe the machine immedi‐
ately – if fuel gets on your clothing, change
immediately.
Check for leakage. To reduce the risk
of serious of fatal burn injuries, do not
start or run the engine until leak is
fixed.
Screw-type fuel cap
After fueling, tighten down the screw-
type fuel cap as securely as possible.
This reduces the risk of unit vibrations causing
the fuel cap to loosen or come off and spill quan‐
tities of fuel.
2.7 Before Starting
Check that your power tool is properly assem‐
bled and in good condition – refer to appropriate
chapters in the instruction manual.
–Check the fuel system for leaks, paying spe‐
cial attention to visible parts such as the tank
cap, hose connections and the manual fuel
pump (on machines so equipped). If there are
any leaks or damage, do not start the engine –
risk of fire. Have your machine repaired by a
servicing dealer before using it again.
–Throttle trigger must move freely and spring
back to the idle position when released.
–The setting lever must move easily to STOP or
0
–The blower tubes must be properly assem‐
bled.
–Keep the handles dry and clean – free from oil
and dirt – for safe control of the power tool.
–Check that the spark plug boot is secure – a
loose boot may cause arcing that could ignite
leaking fuel-air mixture and cause a fire.
–Never attempt to modify the controls or the
safety devices in any way.
–Check condition of blower housing.
–Check condition of harness straps and back‐
pack – replace damaged or worn straps.
A worn blower housing (cracks, nicks, chips)
may result in an increased risk of injury from
thrown foreign objects. If the blower housing is
damaged, consult your dealer – STIHL recom‐
mends you contact a STIHL servicing dealer.
To reduce the risk of accidents, do not operate
your power tool if it is not in a safe condition.
For emergencies: Practice quickly opening the
fastener on the waist belt, loosening the shoulder
straps and setting down the unit.
2.8 Start the engine.
Start the engine at least 3 meters from the fuel‐
ing spot, outdoors only.
Your power tool is designed to be operated by
one person only. Do not allow other persons in
the work area – even when starting.
Do not drop start the power tool – start the
engine as described in the instruction manual.
Place the power tool on level ground, make sure
you have secure footing, hold the power tool
securely.
As soon as the engine starts, the air flow may
throw small objects (e.g. stones) in your direc‐
tion.
English 2 Safety Precautions and Working Techniques
4 0458-391-8321-B

2.9 During Operation
In the event of impending danger or in an emer‐
gency, switch off the engine immediately by mov‐
ing the setting lever to STOP or 0.
To reduce the risk of injury from thrown objects,
do not allow any other persons within 15 meters
of your own position.
To reduce the risk of damage to property, also
maintain this distance from other objects (vehi‐
cles, windows).
Do not direct the air blast towards
bystanders or animals since the air
flow can blow small objects at great
speed – risk of injury.
When blow-sweeping (in open ground and gar‐
dens), watch out for small animals to avoid harm‐
ing them.
Never leave a running machine unattended.
Take special care in slippery conditions – damp,
snow, ice,
on slopes and uneven ground.
Watch out for obstacles: Be careful of refuse,
tree stumps, roots and ditches which could
cause you to trip or stumble.
Never work on a ladder or any other insecure
support.
Be particularly alert and cautious when wearing
hearing protection because your ability to hear
warnings (shouts, alarms, etc.) is restricted.
Work calmly and carefully – in daylight conditions
and only when visibility is good. Stay alert so as
not to endanger others.
To reduce the risk of accidents, take a break in
good time to avoid tiredness or exhaustion.
Your power tool produces toxic
exhaust fumes as soon as the engine
is running. These fumes may be col‐
orless and odorless and contain
unburned hydrocarbons and benzol.
Never run the engine indoors or in
poorly ventilated locations, even if
your model is equipped with a cata‐
lytic 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.
To reduce the risk of accidents, stop work imme‐
diately in the event of nausea, headache, visual
disturbances (e.g. reduced field of vision), prob‐
lems with hearing, dizziness, deterioration in abil‐
ity to concentrate. Apart from other possibilities,
these symptoms may be caused by an exces‐
sively high concentration of exhaust gases in the
work area.
To reduce the risk of fire, do not smoke while
operating or standing near your power tool. Note
that combustible fuel vapor may escape from the
fuel system.
If dust levels are very high, always wear a suita‐
ble respirator.
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.
After finishing work, put the unit down on a level,
non-flammable surface. To reduce the risk of fire,
do not put it down near easily combustible mate‐
rials (e.g. wood chips, bark, dry grass, fuel).
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 Work". Check the fuel system in
particular for leaks and make sure the safety
devices are working properly. Do not continue
operating your power tool if it is damaged. In
case of doubt, consult your servicing dealer.
2.10 Using the Blower
0009BA001 KN
The machine is carried as a backpack. Hold and
control the blower tube with your right hand on
the control handle.
Walk slowly forwards as you work – observe the
nozzle outlet at all times – do not walk back‐
wards – risk of stumbling.
Always shut off the engine before taking the
machine off your back.
2 Safety Precautions and Working Techniques English
0458-391-8321-B 5

2.11 Working Technique
To minimize blowing time, use a rake and broom
to loosen dirt particles before you start blowing.
–If necessary, dampen the surface to be
cleaned in order to avoid creating too much
dust.
–Do not blow particles in the direction of
bystanders, in particular in the direction of chil‐
dren, pets, open windows or freshly washed
vehicles. Take special care in such situations.
–Remove the blow-swept debris in rubbish bins
– do not blow it onto the neighbor's land.
–Operate your power tool at reasonable times
only – not early in the morning, late at night or
during midday rest periods when people could
be disturbed. Observe local rest periods.
–Operate blowers at the lowest engine speed
necessary to accomplish the task.
–Check your blower before starting work. Pay
special attention to the muffler, air intakes and
air filter.
2.12 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:
–Keeping your hands warm
–Work breaks
The period of usage is shortened by:
–Any personal tendency to suffer from poor cir‐
culation (symptoms: frequently cold fingers,
itching).
–Low outside temperatures.
–Gripping force (a tight grip hinders 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.
2.13 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 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 since
there is otherwise a risk of fire from uncontained
sparking.
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.
Vibration behavior is influenced by the condition
of the AV elements – check the AV elements at
regular intervals.
Shut off the engine before rectifying problems.
English 2 Safety Precautions and Working Techniques
6 0458-391-8321-B

3 Assembling the Unit
3.1 Mounting the Hose Clamps and
Pleated Hose
1
0416BA001 KN
2
3
► Push the hose clamp (1) (with retainer for
throttle cable) onto the elbow (3) – the posi‐
tioning marks must face to the left.
► Push the pleated hose (2) over the elbow (3).
2
1
4
0416BA002 KN
3
► Push the hose clamp (1) onto the pleated
hose (2).
► Line up the positioning marks on the hose
clamp (1) and elbow (3) – the screw lug faces
down.
► Secure the hose clamp (1) with the screw (4).
0416BA003 KN
56
2
► Push the hose clamp (5) (without retainer for
throttle cable) onto the blower tube (6) – the
positioning marks must face to the right.
► Push the blower tube (6) into the pleated
hose (2).
56
2
0416BA004 KN
7
► Push the hose clamp (5) onto the pleated
hose (2).
► Line up the hose clamp (5) and blower
tube (6) – as shown.
► Secure the hose clamp (5) with the screw (7).
3.2 Mounting the Control Handle
1
3
2
0000-GXX-2045-A1
► Push the control handle (1) onto the
mount (2) .
► Insert and tighten down the screws (3) firmly.
4
6
5
0416BA008 KN
► Engage the throttle cable (4) with sleeve (5) in
the hose clamp (6).
3 Assembling the Unit English
0458-391-8321-B 7

3.3 Adjusting the Control Handle
0416BA007 A1
1
2
3
► Open the clamping lever (3).
► Move the control handle (1) along the blower
tube (2) to the most comfortable position.
► Close the clamping lever (3).
3.4 Mounting the Nozzle (BR 700)
3
0416BA005 KN
1
2
► Push the nozzle (1) onto the blower tube (2)
and engage it on the lugs (3).
3.4.1 Removing the nozzle (BR 700)
1
3
0416BA006 KN
2
► Rotate the nozzle (1) in the direction of the
arrow until the lugs (3) are covered.
► Pull the nozzle (1) off the blower tube (2).
3.5 Mounting the Nozzle (BR 700
X)
3
1
2
0000-GXX-3989-A0
► Push the nozzle (1) onto the blower tube (2)
and engage it on the lugs (3).
► Rotate the nozzle (1) in the direction of arrow
as far as the stop.
3.5.1 Removing the nozzle (BR 700 X)
1
2
0000-GXX-3990-A0
► Rotate the nozzle (1) in the direction of arrow
as far as the stop.
► Pull the nozzle (1) off the blower tube (2).
3.6 Adjusting the Blower Tube (BR
700)
1
0416BA015 KN
2
► Loosen the union nut (1).
► Pull the blower tube (2) out to the required
length.
► Tighten the union nut (1).
English 3 Assembling the Unit
8 0458-391-8321-B

3.7 Wear Mark on Nozzle
0416BA009 KN
The front end of the nozzle wears away due to
abrasive ground contact during operation. The
nozzle is subject to normal wear and tear and
must be replaced when the wear mark is
reached.
3.8 Transport Aid
When storing or transporting the machine:
► Secure the blower tube to the handle on the
backplate with the hook and loop fastener.
4 Adjusting the Throttle
Cable
It may be necessary to correct the adjustment of
the throttle cable after assembling the machine
or after a prolonged period of operation.
Adjust the throttle cable only when the unit is
completely and properly assembled.
002BA655 KN
► Set the throttle trigger to the full throttle posi‐
tion.
► Carefully rotate the screw in the throttle trigger
in the direction of the arrow until you feel initial
resistance. Then rotate it another half turn in
the same direction.
5 Fitting the Harness
5.1 Adjusting the Harness
373BA003 KN
► Pull the straps downwards to tighten the har‐
ness
5.2 Loosening the Harness
373BA004 KN
► Lift the tabs of the two sliding adjusters.
► Adjust the harness so that the backplate fits
snugly and securely against your back
6 Fuel
The engine requires a mixture of gasoline and
engine oil.
WARNING
Avoid direct skin contact with fuel and breathing
in of gasoline fumes.
6.1 STIHL MotoMix
STIHL recommends using STIHL MotoMix. This
pre-blended fuel is free of benzene and lead, is
distinguished by a high octane rating, and
always provides the proper mixing ratio.
4 Adjusting the Throttle Cable English
0458-391-8321-B 9

STIHL MotoMix uses STIHL HP Ultra two-stroke
engine oil for optimum engine life.
MotoMix is not available in all markets.
6.2 Mixing fuel
NOTICE
Unsuitable fuels or a mixing ratio that deviates
from the specification can lead to severe engine
damage. The engine, seals, fuel lines and fuel
tank may be damaged if low-quality gasoline or
engine oil is used.
6.2.1 Gasoline
Use only high-quality gasoline with an octane rat‐
ing of at least 90 ROC – leaded or unleaded.
Gasoline with an alcohol component exceeding
10% can cause impaired engine performance in
engines with manually adjustable carburetors
and thus should not be used in these engines.
Engines with M-Tronic deliver full engine per‐
formance using gasoline with an alcohol compo‐
nent of up to 27% (E27).
6.2.2 Engine oil
If you mix the fuel yourself, use only STIHL two-
stroke engine oil or another high-performance
engine oil classified as 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.
6.2.3 Mixing ratio
with STIHL two-stroke engine oil 1:50; 1:50 =
1 part oil + 50 parts gasoline
6.2.4 Examples
Quantity of gaso‐
line
STIHL two-stroke
engine oil 1:50
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)
► Pour oil into an approved safety fuel canister
first, then add gasoline and mix thoroughly
6.3 Storing fuel mixture
Store in approved safety fuel canisters only in a
dry, cool and secure place protected against light
and sunlight.
Fuel mixture deteriorates with age – mix only as
much as needed for a few weeks. Do not store
fuel mixture for longer than 30 days. The fuel
mixture can become unusable more quickly if
exposed to light, sunlight or low or high tempera‐
tures.
STIHL MotoMix however can be stored for up to
5 years without any problems.
► Shake the canister containing the fuel mixture
thoroughly before refueling
WARNING
Pressure may have built up in the canister –
open it carefully.
► The fuel tank and the canister in which fuel
mixture is stored should be cleaned thoroughly
from time to time
Residual fuel and the liquid used for cleaning
must be disposed of in accordance with regula‐
tions and without harming the environment!
7 Fueling
7.1 Preparations
0002BA086 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
faces up.
English 7 Fueling
10 0458-391-8321-B

7.2 Opening screw-type tank cap
002BA447 KN
► Turn the cap counterclockwise until it can be
removed from the tank opening.
► Remove the cap.
7.3 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 (special accessory).
7.4 Closing screw-type tank cap
002BA448 KN
► Place the cap in the opening.
► Turn the cap clockwise as far as stop and
tighten it down as firmly as possible by hand.
8 Information Before You
Start
8.1 Positions of Master Control
Lever
1
2
3
0014BA001 AS
1 Setting lever
2 Throttle trigger
3 Starter switch (BR 450 C only)
Engine stop 0 – ignition interrupted, engine
stops. The setting lever does not remain in ths
position, it springs back.
Normal run position F – engine runs or is ready to
start. Throttle trigger can be moved to any posi‐
tion.
0416BA013 KN
2
1
Infinitely variable throttle setting – throttle trigger
can be locked in any required position: Move set‐
ting lever (1) upwards until required engine
speed is reached. To disengage, move the set‐
ting lever back to the normal run position F.
9 Starting / Stopping the
Engine
9.1 Starting the Engine
► Observe safety precautions.
NOTICE
Start your unit on a clean, dust-free surface only
to ensure that no dust is sucked in.
0416BA011 KN
►Move the setting lever to F
8 Information Before You Start English
0458-391-8321-B 11

0009BA012 KN
H
LA
L
► Press the fuel pump bulb at least eight times –
even if the bulb is filled with fuel.
9.1.1 Cold engine (cold start)
0009BA013 KN
►Push the choke knob in and turn it to c.
9.1.2 Warm engine (warm start)
0009BA014 KN
►Push the choke knob in and turn it to o.
Also use this setting if the engine has been run‐
ning but is still cold.
9.1.3 Cranking
0009BA028 KN
► Place the unit securely on the ground and
make sure that bystanders are well clear of
the nozzle outlet.
► Make sure you have a firm footing: Hold the
unit with your left hand on the housing and put
one foot against the base plate to prevent it
slipping.
► Pull the starter grip slowly with your right hand
until you feel it engage and then give it a brisk
strong pull. Do not pull out the starter rope to
full length – it might otherwise break.
► 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 until the engine runs.
9.1.4 Electric start (BR 450 C)
The power tool is equipped with the STIHL elec‐
tric starter for convenient starts.
The STIHL electric starter basically consists of
the following components:
–Rechargeable battery, integrated in control
unit
–Starter mechanism with starter motor and
starter gear
–Starter switch
The battery supplies the starter motor with the
power required to start the engine.
The battery is recharged while the power tool is
running – the power tool is always ready to start.
English 9 Starting / Stopping the Engine
12 0458-391-8321-B

The starter battery is not replaceable – it is inte‐
grated in the control unit.
If the power tool is stored at temperatures below
0°C it may cool down to a point where a start is
inhibited to protect the battery.
The engine must then be started manually.
0014BA005 AS
► Place the unit securely on the ground and
make sure that bystanders and loose objects
are well clear of the nozzle outlet.
► Make sure you have a firm footing: Hold the
unit with your left hand on the carrying handle
and grip the control handle with your right
hand.
Alternative:
0014BA004 AS
► Place the unit securely on the ground and
make sure that bystanders and loose objects
are well clear of the nozzle outlet.
0014BA002 AS
12
► Slide the starter switch downwards.
► Press the starter switch
9.2 As soon as the engine runs
2
0416BA012 KN
► Operate the throttle trigger (2).
0009BA017 KN
► Choke knob automatically returns to the run
position e when the throttle trigger is oper‐
ated.
9.2.1 At very low outside temperatures
► Open throttle slightly – warm up the engine for
a short period.
9 Starting / Stopping the Engine English
0458-391-8321-B 13

9.3 Stopping the Engine
0416BA016 KN
► Move the setting lever to 0 – the engine stops
– the setting lever springs back to the on posi‐
tion.
9.4 Other Hints on Starting
Electric starter does not operate
► Temperature below 0°C, electric starter is
deactivated - start engine manually.
► Low electric starter battery - start engine man‐
ually.
Engine stalls in cold start position c or under
acceleration
►Move the choke knob to o and continue
cranking until the engine runs.
Engine does not start in warm start position o
►Move the choke knob to c and continue
cranking until the engine runs.
If the engine does not start
► Check that all settings are correct.
► Check that there is fuel in the tank and refuel if
necessary.
► Check that the spark plug boot is properly con‐
nected.
► Repeat the starting procedure.
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 according to engine tem‐
perature.
► Now start the engine.
10 Operating Instructions
10.1 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 helps protect engine-mounted
components (ignition, carburetor) from thermal
overload.
10.2 After Finishing Work
Storing for a short period: Wait for the engine to
cool down. 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".
11 Replacing the Air Filter
Dirty air filters reduce engine power, increase
fuel consumption and make starting more diffi‐
cult.
11.1 If there is a noticeable loss of
engine power
1
0002BA088 KN
1
2
►Turn the choke knob to c .
► Loosen the screws (1).
► Remove the filter cover (2).
English 10 Operating Instructions
14 0458-391-8321-B

0002BA089 KN
3
► Remove the filter element (3).
► Replace dirty or damaged filters.
► Fit the new filter in the filter housing.
► Fit the filter cover.
► Fit the screws and tighten them down firmly.
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.
► Check the air filter and clean or replace if nec‐
essary.
► Check that the throttle cable is properly adjus‐
ted – readjust if necessary – see chapter on
"Adjusting the Throttle Cable".
► Check the spark arresting screen (not in all
models, country-specific) in the muffler and
clean or replace if necessary.
12.3 Standard Setting
0002BA082 KN
H
L
► Turn high speed screw (H) counterclockwise
as far as stop (no more than 3/4 turn).
► Turn the low speed screw (L) clockwise as far
as stop, then turn it back 3/4 turn.
12.4 Adjusting Idle Speed
► Carry out the standard setting.
► Start and warm up the engine.
0002BA083 KN
LA
L
12.4.1 Engine stops while idling
► Turn the idle speed screw (LA) slowly clock‐
wise until the engine runs smoothly.
12.4.2 Erratic idling behavior, engine stops
even though setting of LA screw has
been corrected, poor acceleration
Idle setting is too lean
► Turn the low speed screw (L) counterclock‐
wise, no further than stop, until the engine
runs and accelerates smoothly.
12.4.3 Erratic idling behavior
Idle setting is too rich
► Turn the low speed screw (L) clockwise, no
further than stop, 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).
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 the standard setting.
► Warm up the engine.
► Turn high speed screw (H) slightly clockwise
(leaner) – no further than stop.
12 Adjusting the Carburetor English
0458-391-8321-B 15

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
2
0002BA049 KN
► Pull off the spark plug boot (1) vertically.
► Unscrew the spark plug (2).
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.
–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
If out of use for periods of about 30 days or lon‐
ger
► Drain and clean the fuel tank in a well ventila‐
ted area.
► Dispose of fuel properly in accordance with
local environmental requirements.
► If a manual fuel pump is fitted: Press the man‐
ual fuel pump at least 5 times.
► Start the engine and run it at idling speed until
it stops
► Thoroughly clean the machine, especially the
cylinder fins and air filter.
► Store the machine in a dry and safe location.
Keep out of the reach of children and other
unauthorized persons
English 13 Spark Plug
16 0458-391-8321-B

16 Inspections and Mainte‐
nance by Dealer
16.1 Spark Arrestor in Muffler and
Spacer
WARNUNG
To reduce the risk of damage to persons or
objects from contact with hot parts, never oper‐
ate the machine without a spacer, or with the
spacer damaged.
► If the engine is down on power, have the spark
arrestor in the muffler checked
0002BA095 KN
► Check the spacer for damage
► Have a damaged spacer replaced immediately
17 Maintenance and Care
The following intervals apply for normal operating
conditions. The specified intervals must be short‐
ened accordingly when working for longer than nor‐
mal or under difficult cutting conditions (extensive
dust, etc.).
Before starting work
At the end of work and/or daily
Whenever tank is refilled
Weekly
Monthly
Annually
If faulty
If damaged
As required
Complete machine Visual inspection (condi‐
tion, leaks)
X X
Clean X
Control handle Function test X X
Air filter Clean X
replace X
Manual fuel pump (if
present)
check X
Have repaired by a spe‐
cialist dealer1)
X
Fuel pickup body in fuel
tank
Have checked by
dealer1)
X
Have replaced by serv‐
icing dealer1)
X X
Fuel tank Clean X
Carburetor Check idle speed X X
Readjust idle speed X
Spark plug Adjust electrode gap X
Replace after every 100
hours of operation
Intake port for cooling air Visual inspection X
Clean X
Spark arresting screen in
muffler
Check if installed X
Check or replace1) X
16 Inspections and Maintenance by Dealer English
0458-391-8321-B 17

The following intervals apply for normal operating
conditions. The specified intervals must be short‐
ened accordingly when working for longer than nor‐
mal or under difficult cutting conditions (extensive
dust, etc.).
Before starting work
At the end of work and/or daily
Whenever tank is refilled
Weekly
Monthly
Annually
If faulty
If damaged
As required
Spacer, shim check X
Have replaced by serv‐
icing dealer1)
X X
All accessible screws,
nuts and bolts (not
adjusting screws)
Tighten X
Anti-vibration elements check X X X
Have replaced by serv‐
icing dealer1)
X
Blower air intake shield check X X
Clean X
Throttle cable set X
Safety information label replace X
1)STIHL recommends STIHL dealers
18 Minimize Wear and Avoid
Damage
Observing the instructions in this manual helps
reduce the risk of unnecessary wear and dam‐
age to the power tool.
The power tool must be operated, maintained
and stored with the due care and attention
described in this owner's manual.
The user is responsible for all damage caused by
non-observance of the safety precautions, oper‐
ating and maintenance instructions in this man‐
ual. This includes in particular:
–Alterations or modifications to the product not
approved by STIHL.
–Using tools or accessories which are neither
approved or suitable for the product or are of a
poor quality.
–Using the product for purposes for which it
was not designed.
–Using the product for sports or competitive
events.
–Consequential damage caused by continuing
to use the product with defective components.
18.1 Maintenance Work
All the operations described in the "Maintenance
Chart" must be performed on a regular basis. If
these maintenance operations cannot be per‐
formed by the owner, they should be performed
by a servicing dealer.
STIHL recommends that you have servicing and
repair work carried out exclusively by an author‐
ized STIHL servicing dealer. STIHL dealers are
regularly given the opportunity to attend training
courses and are supplied with the necessary
technical information.
If these maintenance operations are not carried
out as specified, the user assumes responsibility
for any damage that may occur. Among other
parts, this includes:
–Damage to the engine due to neglect or defi‐
cient maintenance (e.g. air and fuel filters),
incorrect carburetor adjustment or inadequate
cleaning of cooling air inlets (intake ports, cyl‐
inder fins).
–Corrosion and other consequential damage
resulting from improper storage.
–Damage to the machine resulting from the use
of poor quality replacement parts.
English 18 Minimize Wear and Avoid Damage
18 0458-391-8321-B

18.2 Parts Subject to Wear and Tear
Some parts of the power tool are subject to nor‐
mal wear and tear even during regular operation
in accordance with instructions and, depending
on the type and duration of use, have to be
replaced in good time. Among other parts, this
includes:
–Filters (air, fuel)
–Rewind starter
–Spark plug
–Damping elements of anti-vibration system
19 Main Parts
BR 450
BR 450 C
1
23
9
15
16
17
18
19
20
21
22
23 #
10
11
12
13
14
6
75
8
4
24
0014BA008 AS
1 Straight Nozzle
2 Blower Tube
3 Union Nut
4 Control Handle
5 Start Switch
6 Throttle Trigger
7 Setting Lever
8 Quick-Release Clamp
9 Pleated Hose
10 Back Padding
11 Backplate
12 Harness
13 Carrying Handle
14 Intake Screen
15 Air Filter Cover
16 Carburetor Adjusting Screws
17 Manual Fuel Pump
18 Choke Knob
19 Starter Grip
20 Fuel Filler Cap
21 Fuel Tank
22 Spark Plug Boot
23 Muffler (with Spark Arresting Screen)
24 Spacer
# Serial Number
19.1 Definitions
1. Straight Nozzle
Aims and widens the airstream.
2. Blower Tube
Directs the airstream.
3. Union Nut
Allows simple adjustment of blower tube
length.
4. Control Handle
Handle on the flexible hose to hold and direct
the tube in the required direction. Designed to
help protect against static electricity.
5. Start Switch
Engages the eletric starter.
6. Throttle Trigger
Controls the speed of the engine.
7. Setting Lever
For run and stop. Sets the throttle to various
positions or stops the engine.
8. Quick-Release Clamp
For adjusting the position of the Control Han‐
dle.
9. Pleated Hose
For blowing in the desired direction.
10
.
Back Padding
Increases carrying comfort.
11
.
Backplate
Helps protect the back of the user.
12
.
Harness
For carrying the unit.
13
.
Carrying Handle
For transporting the unit.
14
.
Intake Screen
Helps prevent leaves entering intake.
15
.
Air Filter Cover
Covers and protects the air filter element.
19 Main Parts English
0458-391-8321-B 19

16
.
Carburetor Adjusting Screws
For tuning the carburetor.
17
.
Manual Fuel Pump
Provides additional fuel feed for a cold start.
18
.
Choke Knob
Eases engine starting by enriching mixture.
19
.
Starter Grip
The grip of the pull starter, for starting the
engine.
20
.
Fuel Filler Cap
For closing the fuel tank.
21
.
Fuel Tank
For fuel and oil mixture.
22
.
Spark Plug Boot
Connects the spark plug with the ignition
lead.
23
.
Muffler (with Spark Arresting Screen)
Muffler reduces exhaust noises and diverts
exhaust gases away from operator.
Spark arresting screen is designed to reduce
the risk of fire.
24
.
Spacer
Designed to reduce the risk of burns and fire.
20 Specifications
20.1 Engine
Single-cylinder two-stroke engine
Displacement: 63.3cm3
Cylinder bore: 48 mm
Piston stroke: 35 mm
Idle speed: 3000 rpm
Engine power to ISO 7293: 2.9 kW (3.9 bhp)
20.2 Ignition system
Electronic magneto ignition
Spark plug (suppressed): NGK BPMR 7 A,
BOSCH WSR 6 F
Electrode gap: 0.5 mm
20.3 Fuel system
All-position diaphragm carburetor with integral
fuel pump
Fuel tank capacity: 1700 cm3 (1.7 l)
20.4 Blowing capacity
Blowing force: 28 N
Air velocity 83 m/s
Air throughput: 1090 m3/h
Maximum air speed: 99 m/s
Maximum air flow rate without
blower tube: 1430 m3/h
20.5 Weight
BR 450: 10.6 kg
BR 450 C: 11.5 kg
20.6 Sound and Vibration Levels
When determining sound and vibration levels,
idling and the nominal maximum engine speed
are taken into account in a ratio of 1:6.
For further details on compliance with Vibration
Directive 2002/44/EC, see
www.stihl.com/vib
20.7 Sound pressure level Lpeq in
accordance with DIN EN ISO
22868
BR 450: 102 dB(A
)
BR 450 C: 102 dB(A
)
20.8 Sound power level Lweq in
accordance with DIN EN ISO
22868
BR 450: 108 dB(A
)
BR 450 C: 108 dB(A
)
20.9 Vibration measurement ahv,eq in
accordance with DIN EN
ISO 22867
20.9.1 Standard version
Handle,
right
BR 450: 2.5 m/s2
BR 450 C: 2.5 m/s2
20.9.2 Version with bike handle
Handle, left Handle,
right
BR 450: 2.5 m/s22.5 m/s2
BR 450 C: 2.5 m/s22.5 m/s2
The K‑factor in accordance with Directive
2006/42/EC is 2.0 dB(A) for the sound pressure
level and sound power level; the K‑factor in
accordance with Directive 2006/42/EC is
2.0 m/s2 for the vibration level.
20.10 REACH
REACH is an EC regulation and stands for the
Registration, Evaluation, Authorization and
Restriction of Chemical substances.
English 20 Specifications
20 0458-391-8321-B