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STIHL BR 340, 420
Instruction Manual Manual de instrucciones
Warning!
For safe operation follow all safety precautions in Instruction Manual - improper use can cause serious injury.
Advertencia!
Para su seguridad durante el manejo de este producto, siga siempre las precauciones de seguridad dadas en el manual de instrucciones - el uso indebido puede causar lesiones graves.
Contents
09.fm |
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Guide to Using this Manual .............. |
2 |
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Safety Precautions ........................... |
3 |
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004 01_ |
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Assembling the Blower ................... |
12 |
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Fuel ................................................ |
14 |
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003_ |
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Fueling ............................................ |
15 |
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Information Before You Start |
16 |
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_SE |
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Starting / Stopping the Engine |
16 |
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Operating Instructions |
19 |
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Cleaning the Air Filter ..................... |
19 |
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Motor Management ........................ |
20 |
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Adjusting the Carburetor ................ |
20 |
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recycled. |
Catalytic Converter ......................... |
22 |
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Checking the Spark Plug |
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Spark Arresting Screen in Muffler ... |
23 |
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can be |
Replacing Starter Rope |
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and Rewind Spring ......................... |
24 |
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paper |
Storing the Machine ........................ |
27 |
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Maintenance Chart |
28 |
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oils; |
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Parts and Controls .......................... |
29 |
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paper.free-chlorineon vegetablecontaininks |
Specifications |
31 |
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Special Accessories ....................... |
32 |
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Maintenance and Repairs ............... |
32 |
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STIHL Incorporated Federal |
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and California Emission Control |
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Printed |
Printing |
Warranty Statement ........................ |
33 |
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Trademarks |
35 |
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KG, 2005 |
rin Sted in U |
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AG & Co. |
2. L5P.CP. |
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© ANDREAS STIHL |
0458 373 3021 BM. |
STIHl |
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English / USA
Allow only persons who understand this Manual to operate your blower.
To receive maximum performance and satisfaction from your STIHL blower, it is important that you read and understand the maintenance and safety precautions, starting on page 3, before using your blower.
Contact your STIHL dealer or the STIHL distributor for your area if you do not understand any of the instructions in this Manual.
!Warning!
Because a blower is a high-speed tool, some special safety precautions must be observed as with any other power tool to reduce the risk of personal injury.
Careless or improper use may cause serious or even fatal injury.
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 blower differs from those described in this Manual, please contact your STIHL dealer for information and assistance.
BR 340, BR 340 L, BR 420, BR 420 C |
1 |
English / USA
Guide to Using this Manual
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 understanding 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.
2 |
BR 340, BR 340 L, BR 420, BR 420 C |
Safety Precautions
Warning!
The use of any blower may be dangerous. It is
important that you read, fully understand and
observe the following safety precautions.
!Warning!
Reread the owner`s manual and the safety instructions periodically.
Do not lend or rent your machine without the owner`s manual.
Be sure that anyone using your unit understands the information contained in this manual.
!Warning!
Careless or improper use of the machine may cause serious injury. Have your STIHL Dealer show you how to operate your blower. Observe all applicable local safety regulations, standards and ordinances.
!Warning!
Minors should never be allowed to use a blower. Bystanders, especially children, and animals should not be allowed in the area where a machine is in use.
Never let the unit run unattended.
Most of these safety precautions and warnings apply to the use of all STIHL blowers. Different models may have different parts and controls.
See the appropriate section of your owner`s manual for a description of the controls and function of the parts of your machine.
Safe use of a blower involves
1.the operator
2.the blower
3.the use of the blower.
THE OPERATOR
Physical Condition
You must be in good physical condition and mental health and not under the influence of any substance (drugs, alcohol, etc.) which might impair vision, dexterity or judgment. Do not operate a blower when you are fatigued.
Be alert - if you get tired while operating your machine, take a break. Tiredness may result in loss of control. Working with any blower can be strenuous. If you have any condition that might be aggravated by strenuous work, check with your doctor before operating the machine.
English / USA
Your STIHL blower is equipped with an antivibration system (AV). The AV system is designed to reduce the transmission of engine vibrations to the operator's body. An AV system is recommended for those operators who use blowers on a regular or sustained basis.
Keep the AV system well maintained. A blower with loose components or with damaged or worn AV buffers will tend to have higher vibration levels.
!Warning!
The ignition system of your unit produces an electromagnetic field of a very low intensity. This field may interfere with some pacemakers. To reduce the risk of serious or fatal injury, persons with pacemaker should consult their physician and the pacemaker manufacturer before operating this tool.
BR 340, BR 340 L, BR 420, BR 420 C |
3 |
English / USA
Proper Clothing
!Warning!
To reduce the risk of injury, the operator should wear proper protective apparel.
Clothing must be sturdy and snug-fitting, but allow complete freedom of movement.
!Warning!
Avoid loose-fitting jackets, flared or cuffed pants,
scarfs, unconfined long hair or anything that could be drawn into the air intake.
Use of gloves when working with the blower is recommended.
Good footing is most important. Wear sturdy shoes with nonslip soles.
!Warning!
To reduce the risk of injury associated with the inhalation of dust, use an appropriate dust respirator for the material being blown.
!Warning!
Use of this product can generate dust, mists, and fumes containing chemicals known to cause respiratory disease, cancer, birth defects, or other reproductive harm. If you are unfamiliar with the risks associated with the particular dust, mists or fumes at issue, consult your employer, governmental agencies such as OSHA and NIOSH and other sources on hazardous materials. If the substance being blown or vacuumed is a commercial substance, review the material safety data sheet for that substance and / or consult the material manufacturer / supplier. The state of California and some other authorities, for instance, have published lists of substances known to cause cancer, reproductive toxicity, etc.
Control dust, mist and fumes at the source where possible. In this regard use good work practices and follow the recommendations of OSHA / NIOSH and occupational and trade associations. When the inhalation of toxic dust, mists and fumes cannot be eliminated, the operator and any bystanders should always wear a respirator approved by NIOSH / MSHA for the substance at issue.
!Warning!
Dust with silica in its composition may contain crystalline silica. Silica is a basic component of sand, quartz, brick, clay, granite and numerous other minerals and rocks, including masonry and concrete products.
Repeated and / or sub-stantial inhalation of airborne crystalline silica can cause serious or fatal respira-tory disease, including silicosis. In addi-tion, the state of California and some other authorities have listed respirable crystalline silica as a substance known to cause cancer. When encountering such materials, always follow the re-spiratory precautions mentioned above.
!Warning!
Breathing asbestos dust is dangerous and can cause severe or fatal injury, respiratory illness or cancer. The use and disposal of asbestos containing products have been strictly regulated by OSHA and the Environmental Protection Agency. Do not blow or disturb asbestos or asbestos containing products, such as asbestos insulation. If you have any reason to believe that you might be disturbing asbestos, immediately contact your employer or a local OSHA representative.
4 |
BR 340, BR 340 L, BR 420, BR 420 C |
English / USA
!Warning!
Proper eye protection is a must. Even though the discharge is directed away from the operator, ricochets and bounce backs can occur during blower operations.
Never operate a blower unless wearing goggles or properly fitted safety
glasses with adequate top and side protection which comply with
ANSI Z 87.1 (or your applicable national standard).
Fellow workers must also wear personal protective equipment.
!Warning!
Blower noise may damage your hearing. Wear sound barriers (ear plugs or ear mufflers) to help protect your hearing. Continual and regular users should have their hearing checked regulary.
THE BLOWER
For illustrations and definitions of the blower parts see the chapter on "Parts and Controls"!
!Warning!
Never modify a blower in any way. Only attachments supplied by STIHL or expressly approved by STIHL for use with the specific STIHL blower models are authorized. Although certain unauthorized attachment are useable for the STIHL blower, their use may be extremely dangerous.
THE USE OF THE BLOWER
Transport
Always turn off the engine before taking the machine off your back and putting it down. When transporting your unit in a vehicle, properly secure it to prevent turnover, fuel spillage and damage to the machine.
Adjust carrying harness to suit your size before starting work.
!Warning!
Before starting work, always inspect the rubber buffers which connect the engine to the pack frame. If the buffers are torn or damaged, they should be replaced by your STIHL dealer. Failure of one or more buffers may cause the engine or fuel tank to hit or rub against other parts, and may lead to serious injury from increased vibrations or from fire as the result of fuel leakage.
Fuel
This STIHL unit uses an oil-gasoline mixture for fuel (see the chapter on "Fuel" of your owner`s manual).
BR 340, BR 340 L, BR 420, BR 420 C |
5 |
English / USA
!Warning!
Gasoline is an extremely flammable fuel. If spilled
or ignited by a spark or other ignition source, it can cause fire and serious burn injury or property damage.
!Warning!
To reduce the risk of serious injury from burns, never attempt to refuel the unit until it has been completely removed from the operator.
Use extreme caution when handling gasoline or fuel mix.
Do not smoke or bring any fire or flame near the fuel.
Fueling instructions
Fuel your machine in well-ventilated areas, outdoors only. Always shut off the engine and allow it to cool before refueling. Relieve fuel tank pressure by loosening fuel cap slowly. Never remove fuel filler cap while engine is running.
Select bare ground for fueling and move at least 10 feet (3 m) from the fueling spot before starting the engine. Always tighten fuel filler cap securely after fueling. Wipe off any spilled fuel before starting your blower and check for leakage.
!Warning!
Check for fuel leakage while refueling and during operation. If fuel or oil leakage is found, do not start or run the engine until leak is fixed and spilled fuel has been wiped away. Take care not to get fuel on your clothing. If this happens, change your clothing immediately.
Always store gasoline in approved container.
!Warning!
In order to reduce the risk of fuel spillage and fire from an improperly tightened fuel cap, correctly position and tighten the fuel cap in the fuel tank opening.
!Warning!
Unit vibrations can cause an improperly tightened
fuel filler cap to loosen or
come off and spill
quantities of fuel. In order to reduce the risk of fuel spillage and fire, tighten the fuel filler cap
by hand as securely as possible.
6 |
BR 340, BR 340 L, BR 420, BR 420 C |
English / USA
Before Starting
!Warning!
Never operate your machine if it is damaged, improperly adjusted or not completely and securely assembled.
You should always inspect your unit before starting it. Make sure the controls and safety devices are working properly.
!Warning!
To reduce the risk of injury from thrown parts, check your fanwheel and fan housing for damage (cracks, nicks, chipping). If any damage is found, stop using the unit and contact your STIHL dealer for repair.
:Throttle trigger must move freely and spring back to idle position when released.
:Stop switch must move easily to $
:Tightness of spark plug boot - if boot is loose, sparks may occur and ignite fuel vapor!
:Condition of fanwheel and fan housing.
Starting
!Warning!
Your blower is a one-person machine. To reduce the risk of eye or other injury from thrown objects, insure that bystanders are at least 50 feet (15m) away during use.
Stop the operation immediately if you are approached.
For specific starting instructions, see the appropriate section of your owner`s manual. Place the machine on firm ground or other solid surface in an open area. Maintain good balance and secure footing.
!Warning!
When you pull the starter grip, don`t wrap the starter rope around your hand. Do not allow the grip to snap back, but guide the starter rope slowly back to permit the rope to rewind properly.
Failure to follow this procedure may result in injury to hand or fingers and may damage the starter mechanism.
The assistance of another person may be needed in placing the unit on your back after starting. In order to reduce the risk of injury to the assistant from thrown objects or from contact with fumes, the engine should be kept at idle speed during this brief period, and your assistant should not stand in the area of the outlet nozzle or exhaust. Otherwise, the unit should be started and operated without assistance.
BR 340, BR 340 L, BR 420, BR 420 C |
7 |
English / USA
Muffler and Catalytic Converter
!Warning!
The muffler and other parts of the engine (e.g. fins of the cylinder, spark plug) become hot during operation and remain hot for a while after stopping the engine. To reduce risk of burns do not touch the muffler and other parts while they are hot.
!Warning!
To reduce the risk of fire or burn injury, let the unit cool down before refueling your power tool after use.
!Warning!
Never disassemble or modify your muffler. The muffler could be damaged and cause an increase in heat radiation or sparks, thereby increasing the risk of fire or burn injury. You may also permanently damage the engine. Have your muffler serviced and repaired by your STIHL servicing dealer only.
!Warning!
To reduce the risk of fire or burn injury, keep the area around the muffler clean. Remove all debris such as pine needles, branches or leaves.
!Warning!
Some STIHL blower models are equipped with a catalytic converter, which is designed to reduce the exhaust emissions of the engine
by a chemical process in the muffler. Due to this process, the muffler does not cool down as rapidly as conventional mufflers when the engine returns to idle or is shut off. To reduce the risk of fire and burn injuries, the following specific safety precautions must be observed.
!Warning!
Since a muffler with a catalytic converter cools down less rapidly than conventional mufflers, always set your backpack blower down in the upright position and never locate it where the muffler is near dry brush, grass, wood chips or other combustible materials while it is still hot.
Let the engine cool down sitting on concrete, metal, bare ground or solid wood (e.g. the trunk of a felled tree) away from any combustible substances.
!Warning!
An improperly mounted or damaged cylinder housing or a damaged/ deformed muffler shell may interfere with the cooling effect of the catalytic converter. To reduce the risk of fire or burn injury, do not continue work with a damaged or improperly mounted cylinder housing or a damaged/ deformed muffler shell. Your muffler is furnished with a screen designed to reduce the risk of fire from the emission of hot particles. Due to the heat from the catalytic reaction, this screen on a catalytic converter will normally stay clean and need no service or maintenance. If you experience loss of performance and you suspect a clogged screen, have your muffler maintained by a STIHL servicing dealer.
8 |
BR 340, BR 340 L, BR 420, BR 420 C |
English / USA
Working instructions
Work carefully.
When working with the blower, always wear it on your back using the carrying harness. Wrap your fingers tightly around the handle, keeping the control handle cradled between your thumb and forefinger. Keep your hand in this position to have your machine under control at all times.
Make sure your control handle (and grip for vacuum attachment) are in good condition and free of moisture, pitch, oil or grease.
Operate the blower under good visibility and daylight conditions only.
!Warning!
Your blower produces poisonous exhaust fumes
as soon as the combustible engine is running. These gases (e.g. carbon monoxide) may be color-
less and odorless. To reduce the risk of serious or fatal injury from breathing toxic fumes, never start or run the blower indoors or in poorly ventilated locations. Ensure proper ventilation when working in trenches or other confined areas.
Keep the space behind and beside the engine clear at all times to allow for the escape of hot and toxic exhaust fumes.
353BA039 KN
!Warning!
To reduce the risk of personal injury, do not direct air blast towards bystanders, since the high pressure of the air flow could injure eyes and could blow small objects at great speed.
!Warning!
Always shut off the engine before cleaning or servicing the unit or replacing parts.
!Warning!
The blower fan between the air intake and output openings rotates whenever the engine is running.
Never insert any foreign object into the air intake of the machine or into the nozzle of the blower. It will damage the fan wheel and may cause serious injury to the operator or bystanders as a result of the object or broken parts being thrown out at high speed.
Do not place the blower on the ground when operating at high speed, because small objects such as sand, grass, dust, etc. may be pulled into the air intake and damage the fan wheel.
To reduce the risk of stumbling and loss of control,do not walk backward while operating the machine.
In an emergency, you may slip out of the harness and throw off the machine quickly. Try slipping out of the harness a number of times before using the machine in order to become accustomed with it.
Do not throw off the machine while practising as it could damage the machine.
Pay attention to the direction of the wind, i.e., do not work against the wind.
BR 340, BR 340 L, BR 420, BR 420 C |
9 |
English / USA
Using the Blower
The blower is designed for singlehanded operation. It is carried as a backpack and operated with the right hand on the control handle.
The powerful ground-level airstream can be aimed highly accurately and effectively. It enables the operator to quickly blow-sweep large areas.
The blower may be used only for the operations described in your manual.
The blower can be used for clearing leaves, grass, paper, dust and light snow in yards, gardens, sports stadiums, parks, driveways and parking lots. It is also suitable for clearing forest paths.
Other applications are blowing out pipes, drains, gutters and your carport.
10
Working techniques
To minimize blowing time, use rakes and brooms to loosen debris before blowing.
Recommended working techniques to minimize airborne debris and pollution:
:In dusty conditions, slightly dampen surfaces.
:Use the full blower nozzle extension so the air stream can work close to the ground.
:Do not direct debris at people, children, pets, at open windows or freshly-washed cars. Blow debris safely away.
:After using blowers, CLEAN UP. Dispose of debris in trash receptacles. Do not blow debris onto neighboring properties.
Recommended working techniques to minimize noise:
:Operate power equipment only at reasonable hours - not early in the morning, late at night or during the noon-break when people might be disturbed. Comply with times listed in local ordinances. Usual recommendations are 9:00 a.m. to 12:00 a.m. and 03:00 p.m. to 5:00 p.m. on workdays for professionals. Special considerations should be given to neighbors on weekends.
:Fewer engines mean less noise; therefore use only one piece of power equipment at a time, when possible.
:Operate power blowers at the lowest possible throttle speed to do the job.
:Check your equipment before operation, especially the muffler, air intakes and air filters.
Conserve water by using power blowers instead of hoses for those lawn and garden applications where a blower can be properly used, such as cleaning patios or porches.
BR 340, BR 340 L, BR 420, BR 420 C
English / USA
Using the Vacuum Attachment
(special accessory)
The vacuum is designed to pick up dry material such as leaves, grass, small twigs and bits of paper.
!Warning!
To reduce the risk of
personal injury from fire
and explosion, never
attempt to pick up hot or burning substances (e.g. smoldering ashes, glowing cigarettes)
or combustible fluids (e.g. gasoline, paint thinners).
MAINTENANCE, REPAIR AND STORING
Maintenance, replacement, or repair of the emission control devices and systems may be performed by any nonroad engine repair establishment or individual. However if you claim warranty for a component which has not been serviced or maintained properly or if nonapproved replacement parts were used, STIHL may deny warranty.
Use only identical STIHL replacement parts for maintenance and repair. Use of parts manufactured by others may cause serious or fatal injury.
Follow the maintenance and repair instructions in the appropriate section of your owner's manual. Refer to the maintenance chart at the last pages of this manual.
!Warning!
Always stop the engine and make sure that the fan is stopped before doing any maintenance or repair work or cleaning the blower. Do not attempt any maintenance or repair work not described in your owner's manual. Have such work performed at your STIHL servicing dealer only.
Check fuel filler cap for leaks at regular intervals. Use the specified spark plug and make sure it and the ignition lead are always in good condition.
Tighten all nuts, bolts and screws except the carburetor adjustment screws after each use.
!Warning!
A worn or damaged muffler is a fire hazard and may cause loss of hearing. Check to see that the muffler is in good condition. The blower must not be operated if the muffler is not functioning properly or has been removed.
Remember that the risk of forest fires is greater in hot weather. Use the spark arresting muffler supplied with the unit. Never touch a hot muffler or burn will result.
!Warning!
In order to reduce the risk of fire, do not modify or remove any part of the muffler or spark arrestor.
Keep spark plug and wire connection tight and clean. The spark plug electrode gap should be checked with a feeler gauge at least every 50 operating hours and reset if necessary. Fit a new spark plug if the electrodes are badly pitted.
For any maintenance please refer to the maintenance chart and to the warranty statement near the end of this manual.
Store blower in a dry, high or locked location and out of reach of children.
Before storing for longer than a few days, always empty the fuel tank.
BR 340, BR 340 L, BR 420, BR 420 C |
11 |
English / USA
Assembling the Blower
2 |
3 |
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353BA002 |
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Mounting the Elbow
A combination wrench and carburetor screwdriver are stowed on the underside of the blower.
The throttle cable is already connected and must not be kinked during assembly.
:Push the elbow (1) into the stub (2) as far as it will go – the stops on the elbow and fan housing stub must line up.
: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.
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373BA033 |
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:Secure the throttle cable (4) to the pleated hose with the retainer (5).
Mounting Blower Tube with Straight Nozzle*
Operate the machine only with the blower tube and nozzle properly mounted.
:Push the blower tube (6) into the pleated hose (7).
:Push the nozzle (8) onto the blower tube (6) to position ’a’ (long) or ’b’ (short), as far as lug (9), and rotate it in the direction of the arrow (clockwise) to lock.
:Rotate the pleated hose (7) counterclockwise as far as stop and leave it in that position.
:Turn the control handle (10) counterclockwise to the horizontal position and tighten down the clamp screw (11).
*see "Guide to Using this Manual"
12 |
BR 340, BR 340 L, BR 420, BR 420 C |
English / USA
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373BA039 |
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Mounting Blower Tube with Curved Nozzle*
Operate the machine only with both blower tubes properly mounted.
:Push the blower tube (6) into the pleated hose (7).
:Push blower tube (12) onto blower tube (6) to position ’a’ (long) or ’b’ (short), as far as lug (9), and rotate it in the direction of the arrow (clockwise) to lock.
:Fit the nozzle (13) on the end of the blower tube (12) and rotate it clockwise to engage the bayonet coupling.
:Rotate the pleated hose (7) counterclockwise as far as stop and leave it in that position.
:Turn the control handle (10) counterclockwise to the horizontal position.
:Rotate the complete blower tube assembly until the nozzle discharge opening points in the same direction as the control handle.
:Tighten down the clamp screw (11).
10 |
11 |
373BA002 KN |
Adjusting the Control Handle
:Put the unit on your back.
:Loosen the clamp screw (11).
:Slide the control handle (10) along the pleated hose to the most comfortable position.
:Tighten down the clamp screw (11).
*see "Guide to Using this Manual"
BR 340, BR 340 L, BR 420, BR 420 C |
13 |
English / USA
373BA003 KN
Adjusting the Harness Straps
:Pull the ends of the straps downward to tighten the harness.
373BA004 KN
Loosening the Harness Straps
:Lift the tabs of the two sliding adjusters.
:Adjust the straps so that the backplate is held firmly and comfortably against your back.
Fuel
This engine is certified to operate on unleaded gasoline and the STIHL twostroke engine oil at a mix ratio of 50:1.
Your two-stroke engine requires a mixture of high-quality gasoline and quality two-stroke air cooled engine oil.
Use mid-grade unleaded gasoline with a minimum octane rating of 89 (R+M/2). If the octane rating of the mid-grade gasoline in your area is lower, use premium unleaded fuel.
Fuel with a lower octane rating may increase engine temperatures. This, in turn, increases the risk of piston seizure and damage to the engine.
The chemical composition of the fuel is also important. Some fuel additives not only detrimentally affect elastomers (carburetor diaphragms, oil seals, fuel lines, etc.), but magnesium castings and catalytic converters as well. This could cause running problems or even damage the engine. For this reason STIHL recommends that you use only nationally recognized high-quality unleaded gasoline!
Use only STIHL two-stroke engine oil or equivalent high-quality two-stroke engine oils that are designed for use only in air cooled two-cycle engines.
We recommend STIHL 50:1 two-stroke engine oil since it is specially formulated for use in STlHL engines.
Do not use BIA or TCW rated (twostroke water cooled) mix oils or other mix oils that state they are for use in both water cooled and air cooled engines (e.g., outboard motors, snowmobiles, chainsaws, mopeds, etc.).
Take care when handling gasoline. Avoid direct contact with the skin and avoid inhaling fuel vapor. When filling at the pump, first remove the canister from your vehicle and place the canister on the ground before filling. Do not fill fuel canisters that are sitting in or on a vehicle.
The canister should be kept tightly closed in order to avoid any moisture getting into the mixture.
The machine‘s fuel tank and the canister in which fuel mix is stored should be cleaned as necessary.
14 |
BR 340, BR 340 L, BR 420, BR 420 C |
English / USA
Fueling
Fuel mix ages
Only mix sufficient fuel for a few days work, not to exceed 3 months of storage. Store in approved fuel-canisters only. When mixing, pour oil into the canister first, and then add gasoline. Close the canister and shake it vigorously by hand to ensure proper mixing of the oil with the fuel.
Gaso- |
Oil (STIHL 50:1 or |
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equivalent high-quality oils) |
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US fl.oz |
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2.6 |
2 1/2 |
6.4 |
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12.8 |
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Dispose of empty mixing-oil canisters only at authorized disposal locations.
373BA030 KN
Before fueling, clean the filler cap and the area around it to ensure that no dirt falls into the tank.
Always thoroughly shake the mixture in the canister before fueling your machine.
In order to reduce the risk of burns or other personal injury from
escaping gas vapor and fumes, remove the fuel filler cap carefully so as to allow any pressure build-up in the tank to release slowly.
After fueling, tighten fuel cap
as securely as possible by hand.
373BA007 KN |
Change the fuel pick up body every year.
Before storing your machine for a long period, drain and clean the fuel tank and run engine until carburetor is dry.
BR 340, BR 340 L, BR 420, BR 420 C |
15 |
English / USA
Information
Before You Start
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.
Only machines with catalytic converter
373BA037 KN
:Move the setting lever to idle position.
Machines with a catalytic converter must always be switched off with the setting lever in the idle position because the throttle cable will otherwise disconnect itself from the throttle trigger.
The throttle cable reconnects itself automatically when the setting lever is moved to the idle position.
Starting / Stopping
the Engine
1
373BA008 KN
2 
KN373BA009
: Observe safety precautions – see chapter “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
Note:
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 idle position before switching off the engine.
373BA010 KN
373BA011 KN
: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.
16 |
BR 340, BR 340 L, BR 420, BR 420 C |
English / USA
373BA012 KN |
:Pull the starter grip slowly with your right hand until you feel it engage and 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.
373BA013 KN |
: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.
When engine begins to fire:
:If engine is cold:
Turn choke knob to eand continue cranking until engine runs.
:If engine is warm:
Continue cranking until engine runs.
BR 340, BR 340 L, BR 420, BR 420 C |
17 |
English / USA
2 |
|
373BA014 KN |
|
1 |
|
373BA015 KN |
373BA016 KN |
: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.
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:
:Slide the stop switch (1) to $
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.
:Set the stop switch to 0
:Open the throttle fully.
:Pull the starter rope several times to clear the combustion chamber.
18 |
BR 340, BR 340 L, BR 420, BR 420 C |
English / USA
Operating Instructions |
Cleaning the Air Filter |
During break-in period
A factory new machine should not be run at high revs (full throttle off load) for the first three tank fillings. This avoids unnecessary high loads during the break-in period. As all moving parts have to bed in during the break-in period, the frictional resistances in the engine are greater during this period. The engine develops its maximum power after about 5 to 15 tank fillings.
During operation
After a long period of full-throttle operation, allow engine to run for a while at idle speed so that the heat in the engine can be dissipated by flow of cooling air. This protects enginemounted components (ignition, carburetor) from thermal overload.
After finishing work
Wait for engine to cool down. Drain the fuel tank. Store the machine in a dry place. Check tightness of nuts and screws (not adjusting screws) at regular intervals and retighten as necessary.
1 |
2 |
1 |
373BA017 KN |
Dirty air filters reduce engine power increase fuel consumption and make starting more difficult.
If there is a noticeable loss of engine power
:Turn choke knob to g
:Release the screws (1) and pull off the filter cover (2).
4 |
3 |
5 |
|
||
|
|
373BA018 KN |
:Remove the main filter (3) from the cover and inspect it –
if it is dirty or damaged, fit a new one.
:Take the prefilter (4) out of the filter cover.
:Make sure the prefilter is dry – knock it out on the palm of your hand or blow out with compressed air.
:Always replace a damaged prefilter.
Note:
Always install a new prefilter when you change the main filter.
BR 340, BR 340 L, BR 420, BR 420 C |
19 |
English / USA
:Clean the filter cover and filter chamber.
:Install the main filter and prefilter elements in the filter cover.
:Fit the cover on the filter base (5) and tighten it down firmly.
Motor Management |
Adjusting the Carburetor |
Exhaust emissions are controlled by the design of the fundamental engine parameters and components (e.g. carburation, ignition, timing and valve or port timing) without the addition of any major hardware.
General Information
The carburetor comes from the factory with a standard setting.
This setting provides an optimum fuel-air mixture under most operating conditions.
With this carburetor it is only possible to correct the adjustment of the high speed screw within fine limits.
If the setting is too lean, there is a risk of engine damage due to insufficient lubrication and overheating.
20 |
BR 340, BR 340 L, BR 420, BR 420 C |
English / USA
Standard Setting
H L
373BA043 KN
:Shut off the engine.
:Turn the high speed screw (H) and
low speed screw (L) counterclockwise as far as stop (max. 1/4 turn).
Adjusting Idle Speed
L
LA |
373BA044 KN |
Engine stops while idling
:Carry out standard setting on the low speed screw.
:Turn idle speed screw (LA) clockwise until the engine runs smoothly.
Erratic idling behavior, poor acceleration
:Carry out standard setting on the low speed screw.
:Turn low speed screw (L) counterclockwise until the engine runs and accelerates smoothly.
It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L).
Fine Tuning for Operation at High Altitude or at Sea Level
A slight correction of the setting may be necessary if engine power is not satisfactory when operating at high altitude or at sea level:
:Check standard setting.
:Warm up the engine.
:Turn the high speed screw (H) slightly clockwise (leaner) – on models with limiter caps (H = 1/4), no further than stop.
If the setting is too lean, there is a risk of engine damage due to insufficient lubrication and overheating.
BR 340, BR 340 L, BR 420, BR 420 C |
21 |
English / USA
Catalytic Converter*
Units with a catalytic converter* may only be operated with unleaded gasoline and STIHL two cycle engine oil or equivalent quality two cycle engine oils in a mix ratio of 50:1 (see chapter “Fuel”).
The catalylic converter in the muffler reduces noxious emissions in the exhaust gas.
Correct adjustment of the carburetor (if adjustable) and observance of the specified mix ratio of gasoline and two cycle engine oil are essential to minimize harmful exhaust emissions and ensure a long catalyst service life.
Checking the Spark Plug
000BA002 KN
Wrong fuel mix (too much engine oil in the gasoline), a dirty air filter and unfavorable running conditions (mostly at part throttle etc.) affect the condition of the spark plug. These factors cause deposits to form on the insulator nose which may result in trouble in operation.
If engine is down on power, difficult to start or runs poorly at idling speed, first check the spark plug.
:Remove spark plug – see "Starting / Stopping the Engine".
:Clean dirty spark plug.
:Check electrode gap (A) and readjust if necessary – see "Specifications".
:Use only resistor type spark plugs of the approved range.
Rectify problems which have caused fouling of spark plug:
:Too much oil in fuel mix.
:Dirty air filter.
:Unfavorable running conditions, e.g. operating at part load.
Fit a new spark plug after approx. 100 operating hours
or earlier if the electrodes are badly eroded.
*see “Guide to Using this Manual”
22 |
BR 340, BR 340 L, BR 420, BR 420 C |
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