Instruction ManualSTIHL SR 420
BA_SR340_01_U_D3.book Seite 0 Donnerstag, 10. April 2003 2:12 14
STIH)
1SR 420
English
BA_SE_004_002_01_13.fmPrinted on chlorine-free paper.
Printing inks contain vegetable oils; paper can be recycled.
© ANDREAS STIHL AG & Co. KG, 2008
0458 372 0121 B. M0,25. M8. Md. Printed in Germany
STIHl
Contents
Guide to Using this Manual .............. 2
Safety Precautions and
Working Techniques ......................... 3
Assembling the Machine ................ 10
Harness .......................................... 12
Fuel ................................................ 13
Fueling ............................................ 14
Information Before You Start .......... 15
Starting / Stopping the Engine ........ 15
Calculating Required Quantity
of Solution ...................................... 18
Metering Unit .................................. 20
Filling the Container ........................ 21
Mistblowing ..................................... 22
Cleaning the Air Filter ..................... 22
Adjusting the Carburetor ................ 23
Spark Arresting Screen
in Muffler ......................................... 25
Checking the Spark Plug ................ 25
Replacing Starter Rope and
Rewind Spring ................................ 26
Storing the Machine ........................ 29
Maintenance Chart ......................... 30
Minimize Wear and
Avoid Damage ................................ 31
Parts and Controls .......................... 32
Specifications ................................. 33
Special Accessories ....................... 34
Maintenance and Repairs ............... 34
Certificate of Conformity ................. 35
Quality Certification ........................ 35
Dear Customer,
Thank you for choosing a quality
engineered STIHL product.
This machine has been built using
modern production techniques and
comprehensive quality assurance.
Every effort has been made to ensure
your satisfaction and troublefree use
of the machine.
Please contact your dealer or our
sales company if you have any
queries concerning your machine.
Hans Peter Stihl
2
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SR 420
Pictograms
All the pictograms attached to the
machine are shown and explained in
this manual.
The operating and handling instructions
are supported by illustrations.
Symbols in text
The individual steps or procedures
described in the manual may be marked
in different ways:
:A bullet marks a step or procedure
without direct reference to an
illustration.
A description of a step or procedure that
refers directly to an illustration may
contain item numbers that appear in the
illustration.
Example:
Loosen the screw (1)
Lever (2) ...
In addition to the operating instructions,
this manual may contain paragraphs
that require your special attention. Such
paragraphs are marked with the
symbols described below:
Warning where there is a risk of an
accident or personal injury or
serious damage to property.
Caution where there is a risk of
damaging the machine or its
individual components.
Note or hint which is not essential
for using the machine, but may
improve the operator’s under-
standing of the situation and result
in better use of the machine.
Note or hint on correct procedure in
order to avoid damage to the
environment.
Equipment and features
This instruction manual may refer to
several models with different
features. Components that are not
installed on all models and related
applications are marked with an
asterisk (*). Such components may
be available as special accessories
from your STIHL dealer.
Engineering improvements
STIHL’s philosophy is to continually
improve all of its products. As a result,
engineering changes and improvements
are made from time to time. If the
operating characteristics or the
appearance of your machine differ from
those described in this manual, please
contact your STIHL dealer for
assistance.
Therefore some changes, modifications
and improvements may not be covered
in this manual.
Guide to Using this Manual
3SR 420
English
Special safety
precautions must be
observed when working
with the power tool.
It is important that you
read, fully understand and
observe the following
safety precautions and
warnings. Keep this
instruction manual in a
safe place for later reference.
Non-observance of the safety
precautions may result in serious or
even fatal injury.
Observe all applicable local safety
regulations, standards and ordinances.
If you have never used this power tool
model before: Have your STIHL dealer
or other experienced user show you how
to operate your power tool.
Minors should never be allowed to use a
power tool. Bystanders, especially
children, and animals should not be
allowed in the area where a power tool is
in use.
When the power tool is not in use, shut it
off so that it does not endanger others
and secure it against unauthorized use.
The operator is responsible for avoiding
injury to third parties and 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 contained
in this manual.
Attachments and Replacement
Parts
Only mount parts and accessories that
are explicitly approved for this power
tool model by STIHL or are technically
identical. If you have any questions in
this respect, consult a specialist dealer.
To reduce the risk of accidents or
damage to the power tool, use only high
quality replacement parts and
accessories.
STIHL recommends the use of STIHL
original parts and accessories. The
characteristics of these components are
specifically designed to match your
machine and meet your performance
requirements.
Never modify your power tool in any way
since this can be extremely dangerous
and result in serious or fatal injury.
STIHL excludes any liability for personal
injury or damage to property caused by
using non-approved attachments.
Safety Precautions and
Working Techniques
4
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SR 420
Physical Condition
You must be in good physical condition
and mental health to work with the
power tool. If you have any condition
that might be aggra
vated by strenuous
work, check with
your doctor before
operating the power tool.
Do not operate this power tool while
under the influence of any substance
(drugs, alcohol) which might impair
vision, dexterity or judgment.
Persons with pacemakers: The ignition
system of this unit produces an
electromagnetic field of a very low
intensity. This field may interfere with
some pacemakers. To reduce any risk to
health, STIHL recommends that
persons with pacemakers consult their
physician and the pacemaker
manufacturer before operating this tool.
Applications
This mistblower is suitable for applying
fungicides, herbicides and pesticides.
Typical areas of application are fruit and
vegetable growing, horticulture,
plantations and forestry.
Do not use your power tool for any other
purpose since this may result in
accidents or damage to the tool. Never
attempt to modify your power tool in any
way since this may also result in
accidents or damage to the tool.
Personal Protective Equipment
Wear proper protective clothing and
equipment when operating, filling and
cleaning the power tool. Follow the
instructions provided by the
manufacturer of the plant protection
product regarding protective equipment.
Change clothing immediately if it
becomes contaminated with the plant
protection product.
Clothing must be sturdy
and snug-fitting, but allow
complete freedom of
movement.
For some chemicals it is
necessary to wear an
impermeable coverall. In
addition, wear chemical resistant head
protection when spraying overhead.
Wear safety boots with
non-slip soles that offer
protection against the
products being used.
Never go barefoot or wear
sandals.
5SR 420
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Wear safety glasses and
sound barriers (ear
plugs or earmuffs).
Wear gloves that offer
protection against the
products being used.
Inhaling plant protection products may
damage your health. To reduce such
risks, wear a respirator. Follow the
instructions provided by the
manufacturer of the plant protection
product.
Avoid loose clothing,
scarves, neckties,
jewellery or anything that
could get into the air
intake. Secure unconfined
long hair (e.g. wear a hair
net).
STIHL offers a comprehensive line of
safety clothing and equipment.
Handling Plant Protection
Products
Always reread the directions for use
provided with the plant protection
product. Observe the instructions on
mixing, application, storage and
disposal.
Plant protection products may contain
substances that harm individuals,
animals, plants and the environment –
risk of poisoning and serious or fatal
injuries.
Plant protection products may be used
only by persons specially trained in their
use and handling and the necessary
first-aid procedures.
Always keep the directions for use or the
label of the plant protection product near
at hand so that the doctor can be
immediately informed about the product
in an emergency. In an emergency,
follow the instructions on the label or in
the directions for use provided with the
plant protection product.
Mixing the spray solution
– Only mix as much solution as
required to avoid having quantities
left over.
– Mix different chemicals only
according to instructions – incorrect
mixtures may produce toxic fumes
or explosive solutions.
– Never apply the plant protection
product undiluted.
– Prepare plant protection product
and fill the container outdoors or in
well ventilated locations only.
Filling the container
– Before filling up with solution,
perform a trial run with fresh water
and check all parts of the tool for
leaks.
– Close the stop cock before filling.
– When filling from the water main, do
not immerse the filling hose in the
spray solution – a depression in the
water main may cause the spray
solution to be sucked back into the
water main.
– Place the power tool on a level
surface – do not fill the container
beyond the maximum mark.
– Close the cap of the solution
container firmly after filling.
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Application
– Do not eat, drink or smoke while
working with plant protection
products.
– Never blow out nozzles or other
small parts with your mouth.
– Avoid contact with plant protection
products – change contaminated
clothing immediately.
– Wash hands and face thoroughly
after work.
Unfavorable weather conditions may
result in an incorrect concentration of the
plant protection product. Overdosing
may cause harm to plants and the
environment. Underdosing may negate
the required effect of the treatment.
To avoid damage to the environment
and plants, never operate the power tool
– in windy conditions
– when it is hot (from25°C in the
shade)
– in direct sunlight
In order to avoid injury and damage to
the power tool, never operate the power
tool with
– combustible liquids
– caustic or corrosive substances
– liquids hotter than 50°C
Storage
– Never store the solution in the
container for more than one day
– Store and transport the plant
protection product only in approved
containers
– Do not store plant protection
product together with foods, drinks
or animal feed
– Keep plant protection product out of
reach of children
Disposal
Do not pour residue of plant protection
product and rinsing liquids into
waterways, drains, shafts or gutters.
– Dispose of any residue and used
containers in accordance with local
laws and regulations.
Dusting and Spreading
Attachment
Electrostatic charging with sparking can
occur when working with the dusting and
spreading attachment (special
accessory) – the risk is greater in
extremely dry weather conditions.
For this reason never apply explosive or
combustible materials that may create a
highly concentrated dust cloud. Do not
apply sulphur or compounds containing
sulphur since they are highly explosive
and have a very low ignition point.
Observe directions for use or label of
plant protection product.
To reduce the risk of sparking, explosion
or fire, make sure that the discharge
system is completely and properly
mounted to the machine. The discharge
systems consists of a conductive wire in
the spray tube connected to a metal
chain, which must make contact with a
conductive surface. Do not use the
dusting and spreading attachment on
non-conductive surfaces (e.g. plastic,
asphalt).
It is essential to follow the fitting
instructions supplied with the “Dusting
and Spreading Attachment” mounting
kit.
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Transporting the Power Tool
Always stop the engine.
Transporting in a vehicle:
– Properly secure your power tool to
prevent turnover, fuel spillage and
damage.
– Solution container must be drained
and cleaned.
Fueling
Gasoline is an
extremely flammable
fuel. Keep clear of naked
flames and fire. 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 unit only when it is
standing securely 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 in a well-ventilated
area, outdoors only. If you spill fuel, wipe
the machine immediately – if fuel gets on
your clothing, change immediately.
After fueling, tighten down
the screw-type tank cap
as firmly as possible. This
reduces the risk of unit
vibrations causing the fuel
cap to loosen or come off
and spill quantities of fuel.
To reduce the risk of serious or fatal
burn injuries, check for fuel leakage. If
fuel leakage is found, do not start or run
the engine until leak is fixed.
Before Starting
Check that your power tool is properly
assembled and in good condition,
especially if it has been subjected to
unusually high loads for which it was not
designed (e.g. heavy impact or a fall).
– Throttle trigger must move freely
and spring back to idle position
when released.
– Slide control / stop switch must
move easily to 0 or STOP.
– Check that spark plug boot is secure
– a loose boot may cause arcing
that could ignite combustible fumes
and cause a fire.
– Check the fuel system for leaks.
To avoid the risk of accidents and
personal injury, do not operate your
power tool if it is not in a safe operating
condition.
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Starting the Engine
Start the engine at least 3 meters from
the fueling spot, outdoors only – not in
confined spaces.
Place the unit on firm ground or other
solid surface in an open area. Make sure
you have good balance and secure
footing. Hold the unit securely.
Start the power tool as described in the
instruction manual.
Your power tool is a one-person unit. Do
not allow other persons to be near the
running unit – even when starting.
If an assistant is required to put the
power tool on your back, make sure that
– the engine is running at idle speed
– the stop cock is closed
– the assistant is not standing in the
area of the outlet nozzle
– the assistant must leave the work
area immediately after you have put
the power tool on your back.
Holding and Controlling the
Power Tool
The power tool is carried as a backpack
with the straps of the harness over both
shoulders – never carry the power tool
with the strap over one shoulder.
Work at a slow walking pace, forwards
only – make sure you have a good view
of the nozzle outlet at all times. To
reduce the risk of tripping or stumbling,
do not walk backwards.
Always shut off the engine before taking
the power tool off your back.
Throwing off power tool in an
emergency: Practise quickly opening
the fastener on the hip belt (special
accessory), releasing the strap hooks
and putting down the power tool.
To reduce the risk of injury from spillage,
keep the power tool and container
upright. Do not bend forwards.
During Operation
To reduce the risk of injury, never aim the
airstream in the direction of bystanders
since the air flow can blow small objects
at great speed.
In the event of impending danger or in
an emergency, switch off the engine
immediately by moving the slide control
/ stop switch to STOP or 0.
In an emergency, throw off the power
tool:
– Open the fastener on the hip belt
(special accessory)
– Open the strap hooks
– Throw the power tool to the ground
Always shut off the engine before
leaving the unit unattended.
Take special care in slippery conditions
– damp, snow, ice, on slopes, uneven
ground, etc.
Watch out for obstacles: Roots, ditches,
holes or rubbish which could cause your
to trip or stumble.
Be particularly alert and cautious when
wearing hearing protection because
your ability to hear warnings (shouts,
alarms, etc.) is restricted.
To reduce the risk of accidents, take a
break in good time to avoid tiredness or
exhaustion.
372BA019 KN
9SR 420
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Work calmly and carefully – in daylight
conditions and only when visibility is
good – ensure you do not endanger
others – stay alert at all times.
After finishing work, put the power tool
down on a level, non-flammable surface.
To reduce the risk of fire, do not put it
down near easily combustible materials
(e.g. wood chips, bark, dry grass, fuel).
Mufflers with a catalytic converter can
become particularly hot.
Your power tool produces
toxic exhaust fumes as
soon as the engine is
running. These fumes
may be colorless 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 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.
To reduce the risk of accidents, stop
work immediately in the event of
nausea, headache, visual disturbances
(e.g. reduced field of vision), problems
with hearing, dizziness, deterioration in
ability to concentrate. Apart from other
possibilities, these symptoms may be
caused by an excessively high
concentration of exhaust gases in the
work area.
To reduce 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.
Vibrations
Prolonged use of the unit 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)
– breaks
The period of usage is shortened by:
– Any personal tendency to suffer
from poor circulation (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, seek medical advice.
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Maintenance and repairs
The machine must be serviced regularly.
Do not attempt any maintenance or
repair work not described in your
Owner’s Manual. All other work should
be carried out by a servicing dealer.
STIHL recommends that maintenance
and repair work be carried out only by
authorized STIHL dealers. STIHL
dealers receive regular training and are
supplied with technical information.
Use only high-quality replacement parts,
in order to avoid the risk of accidents or
damage to the machine. Contact a
dealer if in doubt.
STIHL recommends the use of genuine
STIHL spare parts. Such parts have
been optimized for the machine and the
user's requirements.
Before starting any maintenance or
repair work and before cleaning the
machine, always stop the engine and
disconnect the spark plug boot to
avoid all risk of injury if the engine
starts up inadvertently. – Exception:
adjustment of carburetor and idle speed.
Do not service or store the machine near
a naked light – risk of fire due to the
fuel.
Check fuel cap regularly for tightness.
Use only the spark plugs approved by
STIHL – see Specifications.
Inspect ignition lead (insulation in good
condition, secure connection).
To reduce the risk of fire due to ignition
outside the cylinder, move the slide
control / stop switch to STOP or 0 before
turning the engine over on the starter
with the spark plug boot removed or the
spark plug unscrewed.
Check that the muffler is in perfect
working condition.
Do not use the machine if the muffler is
damaged or missing – risk of fire! –
Hearing damage!
Do not touch the hot muffler – risk of
burns!
The condition of the anti-vibration
buffers influences the machine's
vibrations – they must be examined
regularly.
The throttle cable is already
connected and must not be kinked
during assembly.
Mounting the elbow
The combination wrench and carburetor
screwdriver are stowed on the underside
of the machine.
:Line up the stops on the elbow and
stub and push the elbow (1) into the
stub (2) as far as it will go.
:Fit the nut (3) in the hexagon recess
in the stub.
:Insert the screw in the nut from the
other side and tighten moderately –
the elbow must still turn.
Assembling the Machine
372BA023 KN
23
1
11SR 420
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Mounting the extension tube
:Rotate the pleated hose (1) as far as
stop.
:Turn the control handle (2) so that it
is horizontal.
:Push the extension tube (3) into the
pleated hose (1) as far as it will go.
:The metering unit (4) must point in
the same direction as the control
handle.
:Tighten down the clamp screw (5)
(see “Adjusting the control handle”).
Fitting the liquid hose
:Secure liquid hose (1) from the
container to the pleated hose with
the retainer (2).
:Use hose clips (4) to secure hose
(1) and hose (3) to the stubs on the
stop cock.
:Close the stop cock (move lever to
vertical position).
:Fill up with water and check all hose
connections for leaks.
1
372BA024 KN
2
1
372BA025 KN
3
4
5
372BA026 KN
1
372BA027 KN
2
43
372BA028 KN
14
12
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Adjusting the control handle
:Put the machine on your back.
:Loosen the clamp screw (1).
:Slide the control handle (2) along
the tube to the most comfortable
position.
:Tighten down the clamp screw (1)
firmly.
Adjusting the Harness
:Pull the ends of the straps
downward to tighten the harness.
Loosening the Harness
:Lift the tabs of the sliding adjusters.
:Adjust the straps so that the
backplate is held firmly and
comfortably against your back.
Throwing Off Backpack
Before using the machine, make
yourself familiar with how to release and
throw off the backpack.
In an emergency, quickly throw the
machine off 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.
1
2
372BA029 KN
Harness
373BA003 KN
373BA004 KN
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Your engine requires a mixture of
gasoline and engine oil.
For health reasons, avoid direct skin
contact with gasoline and avoid inhaling
gasoline vapor.
STIHL MotoMix
STIHL recommends the use of STIHL
MotoMix. This ready-to-use fuel mix
contains no benzol or lead, has a high
octane rating and ensures that you
always use the right mix ratio.
STIHL MotoMix is specially
formulated for use in STlHL engines
and guarantees a long engine life.
MotoMix is not available in all markets.
Mixing Fuel
Unsuitable fuels or lubricants or mix
ratios other than those specified
may result in serious damage to the
engine. Poor quality gasoline or
engine oil may damage the engine,
sealing rings, hoses and the fuel
tank.
Gasoline
Use only high-quality brand-name
gasoline with a minimum octane rating
of 90 – leaded or unleaded.
If your machine is equipped with a
catalytic converter, you must use
unleaded gasoline.
A few tankfuls of leaded gasoline
will greatly reduce the efficiency of
the catalytic converter.
Engine Oil
Use only quality two-stroke engine oil.
We recommend STIHL two-stroke
engine oil since it is specially
formulated for use in STlHL engines
and guarantees a long engine life.
If STIHL two-stroke engine oil is not
available, use only quality two-stroke oil
designed for use in air cooled engines.
Do not use oils designed for water
cooled engines or engines with a
separate lubricating system (e.g.
conventional four-stroke engines).
Use only STIHL 50:1 two-stroke
engine oil for the fuel mix in models with
a catalytic converter.
Mix Ratio
STIHL 50:1 two-stroke engine oil:
50 parts gasoline to 1 part oil
Other high-quality two-stroke engine
oils:
25 parts gasoline to 1 part oil
Examples
:Use a canister approved for storing
fuel. Pour oil into the canister first,
then add gasoline and mix
thoroughly.
Fuel
Gaso-
line
STIHL
engine oil
50:1
Other high-
quality two-
stroke engine
oils:
25:1
Liters Liters (cc) Liters (cc)
1 0.02 (20) 0.04 (40)
5 0.10 (100) 0.20 (200)
10 0.20 (200) 0.40 (400)
15 0.30 (300) 0.60 (600)
20 0.40 (400) 0.80 (800)
25 0.50 (500) 1.00 (1000)
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Storing Fuel
Store fuel only in approved safety-type
fuel canisters in a dry, cool and safe
location protected from light and the sun.
Fuel mix ages:
Only mix sufficient fuel for a few weeks
work. Do not store fuel mix for longer
than 3 months.
Exposure to light, the sun, low or high
temperatures can quickly make the fuel
mix unusable.
:Thoroughly shake the mixture in the
canister before fueling your
machine.
Pressure may build up in the
canister – open it carefully.
:Clean the fuel tank and canister
from time to time.
Dispose of remaining fuel and
cleaning fluid properly in
accordance with local regulations
and environment requirements.
:Before fueling, clean the filler cap
and the area around it to ensure that
no dirt falls into the tank.
:Position the unit so that the filler cap
is facing up.
Take care not to spill fuel while fueling
and do not overfill the tank.
After fueling, tighten down filler cap
by hand as securely as possible.
Change the fuel pickup body
once every year
:Drain the fuel tank.
:Use a hook to pull the fuel pickup
body out of the tank and take it off
the hose.
:Push the new pickup body into the
hose.
:Place the pickup body in the tank.
Fueling
373BA006 KN
373BA007 KN
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With the engine stopped and before
starting, check the air intakes
between the backplate and
powerhead for blockages and clean
if necessary.
A protective screen is available as a
special accessory to keep the air
intakes clear.
The throttle cable disconnects itself from
the throttle trigger if the engine is not
shut off in the idle position.
The throttle cable reconnects itself
automatically when the setting lever is
moved to the idle position.
:Move the setting lever to the idle
position.
:Observe safety precautions – see
chapter on “Safety Precautions and
Working Techniques”.
:Slide the stop switch (1) to #
:Move the setting lever (2) to the
center position – this is the
starting throttle position
The setting lever can be used to select
any throttle opening between idle speed
(lower stop) and full throttle (upper stop).
Set the lever to the idle position before
switching off the engine.
Before starting
:Move stop cock lever (3) to upright
position.
Information
Before You Start
373BA037 KN
Starting / Stopping
the Engine
373BA008 KN
1
373BA009 KN
2
16
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SR 420
:If the engine is cold, turn the choke
knob to g
:If the engine is warm, turn the
choke lever to e
Also use this position if the engine
has been running but is still cold.
:Put the unit on the ground. Check
that bystanders are well clear of the
general work area and the nozzle.
: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 the starter rope out all
the way as 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.
373BA010 KN373BA011 KN
373BA012 KN
17SR 420
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When engine begins to fire:
:If engine is cold:
Turn choke knob to e and continue
cranking until engine runs.
:If engine is warm:
Continue cranking until engine runs.
As soon as engine runs:
:Move the setting lever (2) to the
lower stop so that the engine settles
down to idle speed.
To shut down the engine:
:Move the stop switch (1) to 0 or
STOP.
At very low outside temperatures:
Allow engine to warm up
As soon as engine runs:
:Move the setting lever to the lower
stop – the engine settles down to
idle speed.
:Open throttle slightly – warm up
engine for a short period.
If the engine does not start:
If you did not turn the choke knob to e
quickly enough after the engine began to
fire, the combustion chamber is flooded.
:Pull off the spark plug boot.
:Unscrew and dry off the spark plug.
:Move the stop switch to 0 or STOP.
:Open the throttle wide.
:Pull the starter rope several times to
clear the combustion chamber.
373BA013 KN
373BA014 KN
2
1
373BA015 KN
373BA016 KN
18
English
SR 420
:Fit the spark plug and reconnect the
spark plug boot.
:Move the stop switch to #
:Turn the choke knob to e
even if the engine is cold.
:Now start the engine.
Fuel tank run until dry and then
refueled
:Pull the starter rope several times to
prime the fuel line.
Step 1:
Determine surface area (m2)
In the case of ground crops, multiply the
length of the field by its width.
The surface area of high-growing plants
is calculated approximately by
multiplying the length of the rows by the
average height of the foliage. The result
is multiplied by the number of rows and
then by two if both sides have to be
treated.
The area in hectares is obtained by
dividing the number of square meters by
10,000.
Example:
A field 120 meters long and 20 meters
wide has to be treated with a pesticide.
Area:
120 m x 30 m = 3,600 m2
3,600 / 10,000 = 0.36 ha
Step 2:
Determine quantity of active
ingredient
Refer to the instructions supplied with
the active ingredient to determine:
:Required quantity of active
ingredient for 1 hectare (ha) and the
:concentration of active ingredient
(mix ratio)
Multiply the required quantity of active
ingredient for 1 ha by the area
determined in Step 1. The result is the
quantity of active ingredient required for
the area to be treated.
Example:
According to the maker’s instructions,
0.4 liters of active ingredient are
required per hectare to obtain a
concentration of 0.1%.
Quantity of active ingredient:
0.4 (l/ha) x 0.36 (ha) = 0.144 l
Calculating Required
Quantity of Solution
19SR 420
English
Step 3:
Determine quantity of solution
The required quantity of solution is
calculated as follows:
TW
–––– x 100 = TB
K
Where:
TW = Quantity of active ingredient in l
K = Concentration in %
TB= Required quantity of solution in l
Example:
In Step 2 the quantity of active ingredient
required was calculated to be 0.144 l.
According to the maker’s instructions,
the concentration is 0.1%.
Quantity of solution:
0.144 l
––––– x 100 = 144 l
0.1%
Step 4:
Determine walking speed
Carry out a trial run with the machine
fueled and the container filled with water.
Operate the spray tube (swing it back
and forth) as it will be during the real run
described below. Determine the
distance walked in one minute.
Also use the trial run to check the
selected working width. In the case of
low-growing crops, the best working
width is 4-5 m. The working width should
be marked with stakes.
Dividing the distance in meters by the
time in minutes gives you the walking
speed in meters per minute (m/min).
Example:
The distance covered in one minute is
10 meters.
Walking speed:
10 m
––––– = 10 m/min
1min
Step 5:
Determine discharge rate
The setting of the metering knob is
calculated as follows:
Va (l) x vb (m/min) x b(m)
–––––––––––––––––––––– = Vc (l/min)
A (m2)
Va= Quantity of solution
vb= Walking speed
Vc= Discharge rate
b = Working width
A = Area
Example:
The values determined in Steps 1-4 and
a working width of 4 m produce the
following discharge rate (setting of
metering knob):
144 l x 10 (m/min) x 4 m
–––––––––––––––––––– = 1.6 l/min
3,600 m2
Hectares (ha) have to be converted into
m2 (ha x 10,000 = m2).
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