BR 420
Instruction Manual2 - 20
English
Contents
1 Guide to Using this Manual.........................2
2 Safety Precautions and Working Techni‐
ques............................................................ 2
3 Assembling the Unit.................................... 6
4 Harness.......................................................8
5 Fuel............................................................. 9
6 Fueling........................................................ 9
7 Information Before You Start.................... 10
8 Starting / Stopping the Engine.................. 10
9 Operating Instructions...............................12
10 Cleaning the Air Filter............................... 13
11 Adjusting the Carburetor........................... 13
12 Catalytic Converter................................... 14
13 Spark Plug................................................ 14
14 Engine Running Behavior......................... 15
15 Spark Arresting Screen in Muffler............. 16
16 Storing the Machine.................................. 16
17 Maintenance and Care..............................17
18 Minimize Wear and Avoid Damage...........17
19 Parts Subject to Wear and Tear................18
20 Main Parts.................................................18
21 Specifications............................................19
22 Maintenance and Repairs......................... 19
23 Disposal.................................................... 20
24 EC Declaration of Conformity................... 20
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 manual fuel pump
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
Special safety precautions must be
observed when operating a power
tool.
It is important that you read and
understand the User Manual before
commissioning and keep it in a safe
place for future reference. Non-com‐
pliance 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 not used this machine before: Have
your dealer or other experienced user show you
how to handle your machine safely or attend a
specialist course.
Minors must never work with the machine –
except for young people over the age of 16 who
are being trained under supervision.
Children, animals and onlookers must not be
allowed near the machine.
When the machine is not in use, put it in a place
where it does not endanger others. Secure the
machine against unauthorized access.
Original Instruction Manual
0000000021_015_GB
Printed on chlorine-free paper
Printing inks contain vegetable oils, paper can be recycled.
© ANDREAS STIHL AG & Co. KG 2022
0458-373-0121-D. VA0.L21.
2 0458-373-0121-D
2 Safety Precautions and Working Techniques English
The user is responsible for accidents or risks
involving third parties or their property.
The machine should only be provided or loaned
to people familiar with this model and its opera‐
tion. The instruction manual should always be
handed over with the machine.
The use of noise-emitting power tools may be
restricted to certain times by national or local
regulations.
Do not operate your machine if any of its compo‐
nents are damaged.
Do not use a high-pressure washer to clean the
power tool. The solid jet of water may damage
parts of the unit.
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 your dealer. Use only high
quality parts and accessories. Otherwise there is
a risk of accidents and damage to the unit.
STIHL recommends the use of original STIHL
parts 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.
2.2 Physical fitness
To operate the power tool you must be rested, in
good physical condition and mental health.
If you have any condition which may be aggrava‐
ted by strenuous work, check with your doctor
before operating a power tool.
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. To reduce health risks,
STIHL recommends that persons with pacemak‐
ers consult their physician and the pacemaker
manufacturer before operating this tool.
Do not operate the power tool 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 power tool for any other purpose
because of the increased risk of accidents and
damage to the power tool itself. The product
must not be modified in any way - this may also
lead to accidents or damage to the unit.
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 any clothing, scarves, neckties,
jewelry or anything that could get into
the air intake. Tie up and confine long
hair above your shoulders so that it
cannot be pulled into the machine.
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.
Wear "personal" sound protection, e.g. ear
defenders.
STIHL can supply a comprehensive range of per‐
sonal protective equipment.
2.5 Transporting the machine
Always stop the engine.
Transporting in a vehicle:
Secure the machine against overturning, dam‐
–
age and fuel spillage
2.6 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 refuel a hot engine. Fuel may spill and
cause a fire.
0458-373-0121-D 3
English
2 Safety Precautions and Working Techniques
Always remove the power tool from your back
before refueling. Refuel 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 to pre‐
vent fuel spraying out.
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.
Check for fuel leakage! Never start
the engine if fuel has been spilled or
is leaking. Fatal burns may result!
After refueling, tighten the screw-type
fuel cap as securely 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.
2.7 Before starting
Check that your machine is properly assembled
and in good condition – refer to appropriate
chapters in the instruction 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
Throttle trigger must move freely and spring
–
back by itself to the idle position
The setting lever must move easily to STOP or
–
0
The blower tubes must be properly assembled
–
Keep the handles dry and clean – free from oil
–
and dirt – this is important for safe control of
the machine
Check that the spark plug boot is secure – a
–
loose boot may cause sparking that could
ignite combustible fumes and cause a fire!
Never attempt to modify the controls or safety
–
devices
Check the condition of the blower housing
–
Wear of the 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
The machine must only be operated when it is in
good operating condition – Risk of accident!
For emergencies: Practice quickly opening the
fastener on the waist belt, loosening the shoulder
straps and setting down the unit.
2.8 Starting 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 user manual.
Place the machine on a flat surface, ensure a
firm and safe footing and hold the machine
securely.
As soon as the engine starts, the increasing air
flow may eject objects (e.g., stones).
2.9 While working
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.
This distance must also be maintained in relation
to objects (vehicles, window panes) – risk of
property damage!
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 terrain and in gar‐
dens), look out for small animals to prevent
endangering them.
Never leave a running machine unattended.
Use caution with slippery surfaces, water, snow,
ice,
on slopes, on uneven ground - Danger of slip‐
ping!
Watch out for obstacles: Be careful of refuse,
tree stumps, roots and ditches which could
cause you to trip or stumble
Do not work on a ladder or in unstable locations.
Be particularly alert and cautious when wearing
hearing protection because your ability to hear
warnings (shouts, alarms, etc.) is restricted.
4 0458-373-0121-D
373BA005 KN
2 Safety Precautions and Working Techniques English
Work calmly and carefully – in daylight conditions
and only when visibility is good. Proceed with
caution, do not put others in danger.
Take breaks when you start getting tired or feel‐
ing fatigue – risk of accidents!
Your power tool produces toxic
exhaust fumes as soon as the engine
is running. These gases may be odor‐
less and invisible and may contain
unburned hydrocarbons and ben‐
zene. 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.
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!
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.
Always wear a dust mask if dust is generated.
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 work, place the machine on a level, nonflammable surface. Do not place the machine
near easily flammable materials (e.g. wood
chips, bark, dry grass, fuel) – risk of fire!
If the machine was exposed to a load for which it
was not designed (e.g., heavy impact or a fall),
always check that it is in good condition before
continuing work – see also "Before Starting".
Check the fuel system for leaks and make sure
the safety devices are working properly. Do not
continue operating your power tool if it is dam‐
aged. In case of doubt, contact a dealer.
2.10 Using the blower
The unit is carried on your back. Hold and control
the blower tube with your right hand on the con‐
trol handle – even if you are left-handed.
Work slowly, moving only in a forward direction.
Always observe the discharge area of the blower
tube. Do not move backward – risk of tripping!
Always shut off the engine before taking the
power tool off your back.
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.
0458-373-0121-D 5
English 3 Assembling the Unit
Check your blower before starting work. Pay
–
special attention to the muffler, air intakes and
air filter.
2.12
Watch out for small animals when vacuuming in
open areas, yards and gardens.
Using the Vacuum Attachment
To reduce the risk of personal injury
from fire, never attempt to pick up hot
or burning substances (e.g. smolder‐
ing ashes, glowing cigarettes).
To reduce the risk of fatal injury from
fire or explosion, never attempt to
pick up combustible fluids (e.g. gaso‐
line) or materials soaked in combusti‐
ble fluids.
2.13 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.
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 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.
2.14 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.
3 Assembling the Unit
3.1 Mounting the Elbow
A combination wrench and carburetor screw‐
driver are stowed on the underside of the blower.
*
Special accessory
6 0458-373-0121-D
353BA002 KN
2
3
1
373BA033 KN
7
4
8
10
6
11
5
9
a
b
373BA039 KN
7
12
10
6
11
9
a
b
13
3 Assembling the Unit English
NOTICE
The throttle cable is already connected and must
not be kinked during assembly.
NOTICE
Operate the machine only with the blower tube
and nozzle properly mounted.
►
Attach the throttle cable (4) to the holder (5).
► Push the blower tube (6) into the pleated
hose (7).
► Push the nozzle (8) in position (a) (long) or
position (b) (short) onto the blower tube as far
as the lpin (9) and rotate the nozzle in the
direction of the arrow to it lock in position.
► Rotate the pleated hose (7) to the left as far as
the limit stop and leave it in that position.
► Turn the control handle (10) to the left until it is
horizontal and tighten the tensioning
screw (11).
3.3 Mounting Blower Tube with
Curved Nozzle
► Push the elbow (1) into the connector (2) as
far as it will go. The limit stops on the elbow
and connector must line up.
► Fit the nuts (3) in the hexagon recesses in the
connector.
► Insert the screws in the nut from the other side
and tighten with moderate force. The elbow
must still turn.
3.2 Mounting Blower Tube with
Straight Nozzle
*
Depending on model
0458-373-0121-D 7
*
NOTICE
Operate the machine only with the blower tube
and nozzle properly mounted.
► Push the blower tube (6) into the pleated
hose (7).
► Push the blower tube (12) in position (a) (long)
or position (b) (short) on the blower tube (6) as
far as the pin (9) and rotate in the direction of
the arrow to lock it in position.
► Fit the nozzle (13) on the end of the blower
tube (12) and turn it clockwise to engage the
bayonet coupling.
► Rotate the pleated hose (7) to the left as far as
the limit stop and leave it in that position.
► Rotate the complete blower tube assembly
until the discharge opening of the nozzle
points in the same direction as the control
handle.
*
11
10
373BA002 KN
0811BA009 KN
373BA003 KN
373BA004 KN
English 4 Harness
► Turn the control handle (10) to the left until it is
horizontal.
► Tighten the tensioning screw (11).
4.2 Adjusting the Harness
3.4 Adjusting the Control Handle
► Pull the ends of the straps downward to
tighten the harness.
4.3 Loosening the Harness
► Put the unit on your back.
► Loosen the tensioning screw (11).
► Slide the control handle (10) along the tube
and adjust it to the user's arm length.
► Tighten the tensioning screw (11).
► Lift the tabs of the sliding adjusters.
► Adjust the harness so that the backplate fits
snugly and securely against your back.
4.4 Throwing Off Machine
4 Harness
4.1 Attaching the Harness
Before using the machine, make yourself familiar
with how to release and throw off the backpack.
In an emergency, quickly throw the machine off
► Attach strap hook to the backplate.
your back as follows:
► Open the quick-release fastener on the waist
belt (special accessory).
► Open the strap hook on the backplate by
snapping it forwards (arrow).
► Throw the machine to the rear.
8 0458-373-0121-D
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