Stihl BR 450, BR 450 C Manual

Guide to Using this Manual

Allow only persons who fully understand this manual to operate your blower.
To receive maximum performance and satisfaction from your STIHL blower, it is important that you read, understand and follow the safety precautions and the operating and maintenance instructions in chapter "Safety Precautions and Working Techniques" before using your blower. For further information you can go to www.stihlusa.com.

Contact your STIHL dealer or the STIHL distributor for your area if you do not understand any of the instructions in this manual.

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.

Pictograms

The meanings of the pictograms attached to or embossed on the machine are explained in this manual.
Depending on the model concerned, the following pictograms may be on your machine.

Fuel tank for gasoline and engine oil mixture

Air intake winter mode

Air intake summer mode

Press to operate manual fuel pump

Symbols in Text

Many operating and safety instructions are supported by illustrations.

A description of a step or procedure that refers directly to an illustration may contain item numbers that appear in the illustration. For example:

• Remove the screw (1)
• Pull the spark arresting screen (2) upwards out of the muffler

In addition to the operating instructions, this manual may contain paragraphs that require your special attention. Such paragraphs are indicated with the symbols and signal words described below:

Indicates a hazardous situation that, if not avoided, will result in death or serious injury.

Indicates a hazardous situation that, if not avoided, could result in death or serious injury.

NOTICE
Indicates a risk of property damage, including damage to the machine or its individual components.

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. Therefore, some changes, modifications and improvements may not be covered in this manual. If the operating characteristics or the appearance of your machine differs from those described in this manual, please contact your STIHL dealer or the STIHL distributor for your area for assistance.

Safety Precautions and Working Techniques

Special safety precautions must be observed when working with a power tool.
It is important that you read the instruction manual before first use and keep it in a safe place for future reference. Nonobservance of the instruction manual may result in serious or even fatal injury.

Observe all applicable local safety regulations, standards and ordinances.

If you have not used this model before: Have your dealer or other experienced user show you how it is operated or attend a special course in its operation.

Minors should never be allowed to use this product.

Keep bystanders, especially children, and animals away from the work area.

When the power tool is not in use, put it in a place where it does not endanger others. Secure it against unauthorized use.

The user is responsible for avoiding injury to third parties or damage to their property.

Do not lend or rent your power tool without the instruction manual. Be sure that anyone using your power tool understands the information contained in this manual.

The use of noise emitting power tools may be restricted to certain times by national or local regulations.

Do not operate your power tool if any of its components are damaged.

Do not use a pressure washer to clean your power tool. The solid jet of water may damage parts of the power tool.

Accessories and replacement parts

Only use parts and accessories that are explicitly approved for this power tool by STIHL or are technically identical. If you have any questions in this respect, consult a servicing dealer. Use only high quality parts and accessories in order to avoid the risk of accidents and damage to the machine.

STIHL recommends the use of original STIHL replacement parts and accessories. They are specifically designed to match the product and meet your performance requirements.

Never attempt to modify your machine in any way since this may increase the risk of personal injury. STIHL excludes all liability for personal injury and damage to property caused while using unauthorized attachments.

Physical Condition

To operate this power tool you must be rested, in good physical condition and mental health.

If you have any condition that might be aggravated by strenuous work, check with your doctor before operating a power tool.

Persons with pacemakers only: The ignition system of your power tool produces an electromagnetic field of a very low intensity. This field may interfere with some pacemakers. To reduce health risks, STIHL recommends that persons with pacemakers consult their physician and the pacemaker manufacturer before operating this power tool.

Do not operate the sprayer if you are under the influence of any substance (drugs, alcohol) which might impair vision, dexterity or judgment.

Intended Use

The blower is designed for blows-weeping leaves, grass, paper and similar materials, e.g. in gardens, sports stadiums, car parks and driveways. It is also suitable for blow-sweeping forest paths.

Do not blow-sweep hazardous materials.

Do not use the machine for any other purpose because of the increased risk of accidents and damage to the machine. Never attempt to modify the product in any way since this may result in accidents or damage to the product.

Clothing and Equipment

Wear proper protective clothing and equipment.

Clothing must be sturdy but allow complete freedom of movement. Wear snug-fitting clothing, an overall and jacket combination, do not wear a work coat.

Avoid clothing with loose drawstrings, laces and ribbons, scarves, neckties, jewelry or anything that could be sucked into the air intake in the side and bottom of the machine. Tie up and confine long hair so that it cannot be sucked into the machine.
Wear sturdy shoes with non-slip soles.

To reduce the risk of eye injuries, wear close-fitting safety glasses in accordance with European Standard EN 166. Make sure the safety glasses are a comfortable and snug fit.
Wear hearing protection, e.g. earplugs or ear muffs.
STIHL offers a comprehensive range of personal protective clothing and equipment.

Transporting the Power Tool

Always shut off the engine.

Transporting in a vehicle:

• Properly secure your power tool to prevent turnover, fuel spillage and damage.

Fueling

Gasoline is an extremely flammable fuel. Keep clear of naked flames. Do not spill any fuel – do not smoke.

Always shut off the engine before refueling.
Do not fuel a hot engine – fuel may spill and cause a fire.

Always remove the power tool from your back and put it on the ground before refueling. Fuel the machine only when it is standing on the ground.

Open the fuel cap carefully to allow any pressure build-up in the tank to release slowly and avoid fuel spillage.

Fuel your power tool only in well-ventilated areas. If you spill fuel, wipe the machine immediately – if fuel gets on your clothing, change immediately.

Check for leakage. To reduce the risk of serious of fatal burn injuries, do not start or run the engine until leak is fixed.

Screw-type fuel cap

After fueling, tighten down the screw-type fuel cap as securely as possible.
This reduces the risk of unit vibrations causing the fuel cap to loosen or come off and spill quantities of fuel.

Before Starting

Check that your power tool is properly assembled and in good condition – refer to appropriate chapters in the instruction manual.

• Check the fuel system for leaks, paying special attention to visible parts such as the tank cap, hose connections and the manual fuel pump (on machines so equipped). If there are any leaks or damage, do not start the engine – risk of fire.
  Have your machine repaired by a servicing dealer before using it again.
• Throttle trigger must move freely and spring back to the idle position when released.
• The setting lever must move easily to STOP or 0
• The blower tubes must be properly assembled.
• Keep the handles dry and clean – free from oil and dirt – for safe control of the power tool.
• Check that the spark plug boot is secure – a loose boot may cause arcing that could ignite leaking fuel air mixture and cause a fire.
• Never attempt to modify the controls or the safety devices in any way.
• Check condition of blower housing.
• Check condition of harness straps and backpack – replace damaged or worn straps.

A worn blower housing (cracks, nicks, chips) may result in an increased risk of injury from thrown foreign objects. If the blower housing is damaged, consult your dealer – STIHL recommends you contact a STIHL servicing dealer.

To reduce the risk of accidents, do not operate your power tool if it is not in a safe condition.

For emergencies: Practice quickly opening the fastener on the waist belt, loosening the shoulder straps and setting down the unit.

Start the engine

Start the engine at least 3 meters from the fueling spot, outdoors only.
Your power tool is designed to be operated by one person only. Do not allow other persons in the work area – even when starting.
Do not drop start the power tool – start the engine as described in the instruction manual.
Place the power tool on level ground, make sure you have secure footing, hold the power tool securely.
As soon as the engine starts, the air flow may throw small objects (e.g. stones) in your direction.

During Operation

In the event of impending danger or in an emergency, switch off the engine immediately by moving the setting lever to STOP or 0.

To reduce the risk of injury from thrown objects, do not allow any other persons within 15 meters of your own position.

To reduce the risk of damage to property, also maintain this distance from other objects (vehicles, windows).

Do not direct the air blast towards bystanders or animals since the air flow can blow small objects at great speed – risk of injury.

When blow-sweeping (in open ground and gardens), watch out for small animals to avoid harming them.

Never leave a running machine unattended.

Take special care in slippery conditions – damp, snow, ice, on slopes and uneven ground.

Watch out for obstacles: Be careful of refuse, tree stumps, roots and ditches which could cause you to trip or stumble.

Never work on a ladder or any other insecure support.

Be particularly alert and cautious when wearing hearing protection because your ability to hear warnings (shouts, alarms, etc.) is restricted.

Work calmly and carefully – in daylight conditions and only when visibility is good. Stay alert so as not to endanger others.

To reduce the risk of accidents, take a break in good time to avoid tiredness or exhaustion.

Your power tool produces toxic exhaust fumes as soon as the engine is running. These fumes may be 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 the risk of fire, do not smoke while operating or standing near your power tool. Note that combustible fuel vapor may escape from the fuel system.

If dust levels are very high, always wear a suitable respirator.

Operate your power tool so that it produces a minimum of noise and emissions – do not run the engine unnecessarily, accelerate the engine only when working.

After finishing work, put the unit down on a level, non-flammable surface. To reduce the risk of fire, do not put it down near easily combustible materials (e.g. wood chips, bark, dry grass, fuel).

If your power tool is subjected to unusually high loads for which it was not designed (e.g. heavy impact or a fall), always check that it is in good condition before continuing work – see also "Before Starting Work". Check the fuel system in particular for leaks and make sure the safety devices are working properly. Do not continue operating your power tool if it is damaged. In case of doubt, consult your servicing dealer.

Using the Blower

The machine is carried as a backpack. Hold and control the blower tube with your right hand on the control handle.

Walk slowly forwards as you work – observe the nozzle outlet at all times – do not walk backwards – risk of stumbling.

Always shut off the engine before taking the machine off your back.

To minimize blowing time, use a rake and broom to loosen dirt particles before you start blowing.

Recommended working technique to minimize air pollution:

• 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 children, 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.

Recommended working technique to minimize noise:

• Operate your power tool at reasonable times only – not early in the morning, late at night or during midday rest periods when people could be disturbed. Observe local rest periods.
• Operate blowers at the lowest engine speed necessary to accomplish the task.
• Check your blower before starting work. Pay special attention to the muffler, air intakes and air filter.

Vibrations

Prolonged use of the power tool may result in vibration-induced circulation problems in the hands (whitefinger disease).

No general recommendation can be given for the length of usage because it depends on several factors.

The period of usage is prolonged by:

• Keeping your hands warm
• Work breaks

The period of usage is shortened by:

• Any personal tendency to suffer from poor 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 (e.g. tingling sensation in fingers), seek medical advice.

Maintenance and Repairs

Service the machine regularly. Do not attempt any maintenance or repair work not described in the instruction manual. Have all other work performed by a servicing dealer.

STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer. STIHL dealers are regularly given the opportunity to attend training courses and are supplied with the necessary technical information.

Only use high-quality replacement parts in order to avoid the risk of accidents and damage to the machine. If you have any questions in this respect, consult a servicing dealer.

STIHL recommends the use of genuine STIHL replacement parts. They are specifically designed to match your model and meet your performance requirements.

To reduce the risk of injury, always shut off the engine before carrying out any maintenance or repairs or cleaning the machine. – Exception: Carburetor and idle speed adjustments.

Do not turn the engine over on the starter with the spark plug boot or spark plug removed since there is otherwise a risk of fire from uncontained sparking.

Do not service or store your machine near open flames.

Check the fuel filler cap for leaks at regular intervals.

Use only a spark plug of the type approved by STIHL and make sure it is in good condition – see "Specifications".

Inspect the ignition lead (insulation in good condition, secure connection).

Check the condition of the muffler.

To reduce the risk of fire and damage to hearing, do not operate your machine if the muffler is damaged or missing.

Do not touch a hot muffler since burn injury will result.

Vibration behavior is influenced by the condition of the AV elements – check the AV elements at regular intervals.

Shut off the engine before rectifying problems.

Assembling the Unit

Mounting the Hose Clamps and Pleated Hose

• Push the hose clamp (1) (with retainer for throttle cable) onto the elbow (3) – the positioning marks must face to the left.
• Push the pleated hose (2) over the elbow (3).
  
• Push the hose clamp (1) onto the pleated hose (2).
• Line up the positioning marks on the hose clamp (1) and elbow (3) – the screw lug faces down.
• Secure the hose clamp (1) with the screw (4).
  
• Push the hose clamp (5) (without retainer for throttle cable) onto the blower tube (6) – the positioning marks must face to the right.
• Push the blower tube (6) into the pleated hose (2).
  

• Push the hose clamp (5) onto the pleated hose (2).
• Line up the hose clamp (5) and blower tube (6) – as shown.
• Secure the hose clamp (5) with the screw (7).
  

Mounting the Control Handle

• Push the control handle (1) onto the mount (2).
• Insert and tighten down the screws (3) firmly.
  

• Engage the throttle cable (4) with sleeve (5) in the hose clamp (6).
  

Adjusting the Control Handle

• Open the clamping lever (3).
• Move the control handle (1) along the blower tube (2) to the most comfortable position.
• Close the clamping lever (3).
  

Mounting the Nozzle (BR 700)

• Push the nozzle (1) onto the blower tube (2) and engage it on the lugs (3).
  

Removing the nozzle (BR 700)

• Rotate the nozzle (1) in the direction of the arrow until the lugs (3) are covered.
• Pull the nozzle (1) off the blower tube (2).
  

Mounting the Nozzle (BR 700 X)

• Push the nozzle (1) onto the blower tube (2) and engage it on the lugs (3).
• Rotate the nozzle (1) in the direction of arrow as far as the stop.
  

Removing the nozzle (BR 700 X)

• Rotate the nozzle (1) in the direction of arrow as far as the stop.
• Pull the nozzle (1) off the blower tube (2).
  

Adjusting the Blower Tube (BR 700)

• Loosen the union nut (1).
• Pull the blower tube (2) out to the required length.
• Tighten the union nut (1).
  

Wear Mark on Nozzle

The front end of the nozzle wears away due to abrasive ground contact during operation. The nozzle is subject to normal wear and tear and must be replaced when the wear mark is reached.

Transport Aid

When storing or transporting the machine:

• Secure the blower tube to the handle on the backplate with the hook and loop fastener.

Adjusting the Throttle Cable

It may be necessary to correct the adjustment of the throttle cable after assembling the machine or after a prolonged period of operation.
Adjust the throttle cable only when the unit is completely and properly assembled.

• Set the throttle trigger to the full throttle position.
• Carefully rotate the screw in the throttle trigger in the direction of the arrow until you feel initial resistance. Then rotate it another half turn in the same direction.

Fitting the Harness

Adjusting the Harness

• Pull the ends of the straps downwards to tighten the harness.
  

Loosening the Harness

• Lift the tabs of the sliding adjusters.
• Adjust the harness so that the backplate fits snugly and securely against your back.
  

Fuel

This engine is certified to operate on unleaded gasoline and the STIHL two-stroke engine oil at a mix ratio of 50:1.

Your engine requires a mixture of high-quality gasoline and two-stroke air cooled engine oil.

Use mid-grade unleaded gasoline with a minimum octane rating of 89 ((R+M)/2) and no more than 10% ethanol content.

NOTICE
Fuel with an octane rating below 89 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 damage the engine. For this reason STIHL recommends that you use only quality unleaded gasoline!

NOTICE
Gasoline with an ethanol content of more than 10% can cause running problems and major damage in engines and should not be used.
For further details, see www.STIHLusa.com/ethanol
The ethanol content in gasoline affects engine speed – it may be necessary to readjust the carburetor if you use fuels with various ethanol contents.

To reduce the risk of personal injury from loss of control and/or contact with the running cutting tool, do not use your unit with an incorrect idle adjustment. At correct idle speed, the cutting tool should not move.

If your machine's idle speed is incorrectly adjusted, have your authorized STIHL servicing dealer check your machine and make the proper adjustments and repairs.

The idle speed and maximum speed of the engine change if you switch from a fuel with a certain ethanol content to a fuel with a much higher or lower ethanol content.

This problem can be avoided by always using fuel with the same ethanol content.

To ensure the maximum performance of your STIHL engine, use a high quality 2cycle engine oil. To help your engine run cleaner and reduce harmful carbon deposits, STIHL recommends using STIHL HP Ultra 2-cycle engine oil or ask your dealer for an equivalent fully synthetic 2-cycle engine oil.

To meet the requirements of EPA and CARB we recommend to use STIHL HP Ultra oil.

STIHL MotoMix

STIHL recommends the use of STIHL MotoMix. STIHL MotoMix has a high octane rating and ensures that you always use the right gasoline/oil mix ratio.

STIHL MotoMix uses STIHL HP Ultra two-stroke engine oil suited for high performance engines.

For further details, see www.STIHLusa.com/ethanol

If not using MotoMix, use only STIHL two-stroke engine oil or equivalent highquality two-stroke engine oils that are designed for use in air cooled two-cycle engines.

The use of non-seasonal gasoline blends may increase the potential for pressure to build in the fuel tank during operation. For example, using a winter blend during the summer will increase pressure in the fuel tank. Always use gasoline blends appropriate to the season, altitude and other environmental factors.

Do not use NMMA or TCW rated (two-stroke 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, chain saws, 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 container from your vehicle and place the container on the ground before filling. To reduce the risk of sparks from static discharge and resulting fire and/or explosion, do not fill fuel containers that are sitting in or on a vehicle or trailer.

The container should be kept tightly closed in order to limit the amount of moisture that gets into the mixture.

The machine's fuel tank should be cleaned as necessary.

Fuel mix ages

If not using MotoMix, only mix sufficient fuel for a few days of work, not to exceed 30 days of storage. Store in approved fuel-containers only. When mixing, pour oil into the container first, and then add gasoline. Close the container and shake it by hand to ensure proper mix of oil and gasoline.

Shaking fuel can cause pressure to build in the fuel container. To reduce the risk of fire and severe personal injury or property damage from fuel spraying, allow the fuel container to sit for several minutes before opening. Open the container slowly to release any residual pressures. Never open the fuel container in the vicinity of any ignition source. Read and follow all warnings and instructions that accompany your fuel container.

Gasoline US gal.	Oil (STIHL 50:1 or equivalent high-quality oils) US fl.oz.
1	2.6
2 1/2	6.4
5	12.8

Dispose of empty mixing-oil containers only at authorized disposal locations.

Fueling

Preparations

• Before fueling, clean the filler cap and the area around it to ensure that no dirt falls into the tank.
  

Opening screw-type tank cap

• Turn the cap counterclockwise until it can be removed from the tank opening.
• Remove the cap.
  

Take care not to spill fuel while fueling and do not overfill the tank. STIHL recommends you use the STIHL filler nozzle (special accessory).

Closing screw-type tank cap

• Place the cap in the opening.
• Turn the cap clockwise as far as stop and tighten it down as firmly as possible by hand.
  

Information Before You Start

Positions of Master Control Lever

1. Setting lever
2. Throttle trigger
3. Starter switch (BR 450 C only)

Engine stop 0 – ignition interrupted, engine stops. The setting lever does not remain in ths position, it springs back.

Normal run position I – engine runs or is ready to start. Throttle trigger can be moved to any position.

Infinitely variable throttle setting – throttle trigger can be locked in any required position: Move setting lever (1) upwards until required engine speed is reached. To disengage, move the setting lever back to the normal run position I.

Starting / Stopping the Engine

Starting the Engine

• Observe safety precautions.

NOTICE
Start your unit on a clean, dust-free surface only to ensure that no dust is sucked in.

• Move the setting lever to I
  
• Press the fuel pump bulb at least eight times – even if the bulb is filled with fuel.
  

Cold engine (cold start)

• Push the choke knob in and turn it to .
  

Warm engine (warm start)

• Push the choke knob in and turn it to .
  
  Also use this setting if the engine has been running but is still cold.

Cranking

• Place the unit securely on the ground and make sure that bystanders are well clear of the nozzle outlet.
• Make sure you have a firm footing: Hold the unit with your left hand on the housing and put one foot against the base plate to prevent it slipping.
• Pull the starter grip slowly with your right hand until you feel it engage and then give it a brisk strong pull. Do not pull out the starter rope to full length – it might otherwise break.
  
• Do not let the starter grip snap back. Guide it slowly back into the housing so that the starter rope can rewind properly.
• Continue cranking until the engine runs.

Electric start (BR 450 C)

The power tool is equipped with the STIHL electric starter for convenient starts.

The STIHL electric starter basically consists of the following components:

• Rechargeable battery, integrated in control unit
• Starter mechanism with starter motor and starter gear
• Starter switch

The battery supplies the starter motor with the power required to start the engine.

The battery is recharged while the power tool is running – the power tool is always ready to start.

The starter battery is not replaceable – it is integrated in the control unit.

If the power tool is stored at temperatures below 0°C it may cool down to a point where a start is inhibited to protect the battery.

The engine must then be started manually.

• Place the unit securely on the ground and make sure that bystanders and loose objects are well clear of the nozzle outlet.
• Make sure you have a firm footing: Hold the unit with your left hand on the carrying handle and grip the control handle with your right hand.

Alternative:

• Place the unit securely on the ground and make sure that bystanders and loose objects are well clear of the nozzle outlet.
• Slide the starter switch downwards.
  
• Press the starter switch
  

As soon as the engine runs

• Operate the throttle trigger (2).
  
• Choke knob automatically returns to the run position when the throttle trigger is operated.
  

At very low outside temperatures

• Open throttle slightly – warm up the engine for a short period.

Stopping the Engine

• Move the setting lever to 0 – the engine stops – the setting lever springs back to the on position.
  

Other Hints on Starting

Electric starter does not operate

• Temperature below 0°C, electric starter is deactivated - start engine manually.
• Low electric starter battery - start engine manually.

Engine stalls in cold start position or under acceleration

• Move the choke knob to and continue cranking until the engine runs.

Engine does not start in warm start position

• Move the choke knob to and continue cranking until the engine runs.

If the engine does not start

• Check that all settings are correct.
• Check that there is fuel in the tank and refuel if necessary.
• Check that the spark plug boot is properly connected.
• Repeat the starting procedure.

Fuel tank run until completely dry

• After refueling, press the manual fuel pump bulb at least five times – even if the bulb is filled with fuel.
• Set the choke knob according to engine temperature.
• Now start the engine.

Operating Instructions

During Operation

After a long period of full throttle operation, allow the engine to run for a short while at idle speed so that engine heat can be dissipated by the flow of cooling air. This helps protect engine-mounted components (ignition, carburetor) from thermal overload.

After Finishing Work

Storing for a short period: Wait for the engine to cool down. Keep the machine in a dry place, well away from sources of ignition, until you need it again. For longer out-of-service periods – see "Storing the Machine".

Replacing the Air Filter

Dirty air filters reduce engine power, increase fuel consumption and make starting more difficult.

If there is a noticeable loss of engine power

• Turn the choke knob to .
• Loosen the screws (1).
• Remove the filter cover (2).
  
• Remove the filter element (3).
• Replace dirty or damaged filters.
• Fit the new filter in the filter housing.
• Fit the filter cover.
• Fit the screws and tighten them down firmly.
  

Engine Management

Exhaust emissions are controlled by the design of the engine and components (e.g. carburation, ignition, timing and valve or port timing).

Adjusting the Carburetor

General Information

The carburetor comes from the factory with a standard setting.
This setting provides an optimum fuel-air mixture under most operating conditions.

Preparations

• Shut off the engine.
• Check the air filter and clean or replace if necessary.
• Check that the throttle cable is properly adjusted – readjust if necessary – see chapter on "Adjusting the Throttle Cable".
• Check the spark arresting screen (not in all models, country-specific) in the muffler and clean or replace if necessary.

Standard Setting

• Turn high speed screw (H) counterclockwise as far as stop (no more than 3/4 turn).
• Turn the low speed screw (L) clockwise as far as stop, then turn it back 3/4 turn.
  

Adjusting Idle Speed

• Carry out the standard setting.
• Start and warm up the engine.
  

Engine stops while idling

• Turn the idle speed screw (LA) slowly clockwise until the engine runs smoothly.

Erratic idling behavior, engine stops even though setting of LA screw has been corrected, poor acceleration

Idle setting is too lean

• Turn the low speed screw (L) counterclockwise, no further than stop, until the engine runs and accelerates smoothly.

Erratic idling behavior

Idle setting is too rich

• Turn the low speed screw (L) clockwise, no further than stop, until the engine runs and accelerates smoothly.

It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L).

Fine Tuning for Operation at High Altitude

A slight correction of the setting may be necessary if the engine does not run satisfactorily:

• Carry out the standard setting.
• Warm up the engine.
• Turn high speed screw (H) slightly clockwise (leaner) – no further than stop.

NOTICE
After returning from high altitude, reset the carburetor to the standard setting.
If the setting is too lean there is a risk of engine damage due to insufficient lubrication and overheating.

Spark Plug

• If the engine is down on power, difficult to start or runs poorly at idle speed, first check the spark plug.
• Fit a new spark plug after about 100 operating hours – or sooner if the electrodes are badly eroded. Install only suppressed spark plugs of the type approved by STIHL – see "Specifications".

Removing the spark plug

• Pull off the spark plug boot (1) vertically.
• Unscrew the spark plug (2).
  

Checking the Spark Plug

• Clean dirty spark plug.
• Check electrode gap (A) and readjust if necessary – see "Specifications".
  
• Rectify the problems which have caused fouling of the spark plug.

Possible causes are:

• Too much oil in fuel mix.
• Dirty air filter.
• Unfavorable running conditions.
  

Arcing may occur if the adapter nut (1) is loose or missing. Working in an easily combustible or explosive atmosphere may cause a fire or an explosion. This can result result in serious injuries or damage to property.

• Use resistor type spark plugs with a properly tightened adapter nut.

Installing the spark plug

• Screw the spark plug (3) into the cylinder and fit the boot (2) (press it down firmly).
  

Storing the Machine

For periods of 3 months or longer

• Drain and clean the fuel tank in a well ventilated area.
• Dispose of fuel properly in accordance with local environmental requirements.
• Run the engine until the carburetor is dry – this helps prevent the carburetor diaphragms sticking together.
• Thoroughly clean the machine – pay special attention to the cylinder fins and air filter.
• Store the machine in a dry, high or locked location, – out of the reach of children and other unauthorized persons.

Inspections and Maintenance by Dealer

Spark Arrestor in Muffler and Spacer

• If the engine is down on power, have the spark arrestor in the muffler checked.
  
• Check spacer for damage.
• Have damaged spacer replaced immediately.

Maintenance and Care

Main Parts

1. Straight Nozzle
2. Blower Tube
3. Union Nut
4. Control Handle
5. Start Switch
6. Throttle Trigger
7. Setting Lever
8. Quick-Release Clamp
9. Pleated Hose
10. Back Padding
11. Backplate
12. Harness
13. Carrying Handle
14. Intake Screen
15. Air Filter Cover
16. Carburetor Adjusting Screws
17. Manual Fuel Pump
18. Choke Knob
19. Starter Grip
20. Fuel Filler Cap
21. Fuel Tank
22. Spark Plug Boot
23. Muffler (with Spark Arresting Screen)
24. Spacer
    # Serial Number

Definitions

1. Straight Nozzle
   Aims and widens the airstream.
2. Blower Tube
   Directs the airstream.
3. Union Nut
   Allows simple adjustment of blower tube length.
4. Control Handle
   Handle on the flexible hose to hold and direct the tube in the required direction. Designed to help protect against static electricity.
5. Start Switch
   Engages the electric starter.
6. Throttle Trigger
   Controls the speed of the engine.
7. Setting Lever
   For run and stop. Sets the throttle to various positions or stops the engine.
8. Quick-Release Clamp
   For adjusting the position of the Control Handle.
9. Pleated Hose
   For blowing in the desired direction.
10. Back Padding
    Increases carrying comfort.
11. Backplate
    Helps protect the back of the user.
12. Harness
    For carrying the unit.
13. Carrying Handle
    For transporting the unit.
14. Intake Screen
    Helps prevent leaves entering intake.
15. Air Filter Cover
    Covers and protects the air filter element.
16. Carburetor Adjusting Screws
    For tuning the carburetor.
17. Manual Fuel Pump
    Provides additional fuel feed for a cold start.
18. Choke Knob
    Eases engine starting by enriching mixture.
19. Starter Grip
    The grip of the pull starter, for starting the engine.
20. Fuel Filler Cap
    For closing the fuel tank.
21. Fuel Tank
    For fuel and oil mixture.
22. Spark Plug Boot
    Connects the spark plug with the ignition lead.
23. Muffler (with Spark Arresting Screen)
    Muffler reduces exhaust noises and diverts exhaust gases away from operator. Spark arresting screen is designed to reduce the risk of fire.
24. Spacer
    Designed to reduce the risk of burns and fire.

Specifications

EPA / CEPA

The Emission Compliance Period referred to on the Emissions Compliance Label indicates the number of operating hours for which the engine has been shown to meet Federal emission requirements.

Category
A = 300 hours
B = 125 hours
C = 50 hours

Engine

Single-cylinder two-stroke engine

Displacement:	63.3 cm3
Cylinder bore:	48 mm
Piston stroke:	35 mm
Idle speed:	3,000 rpm
Engine power according to ISO 7293:	2.9 kW (3.9 HP)

Ignition system

Electronic magneto ignition

Spark plug (suppressed):	NGK BPMR 7 A
Electrode gap:	0.5 mm

This ignition system fulfills all requirements of the Canadian Interference-Causing Equipment Standard CAN ICES-2/NMB-2.

Fuel system

All-position diaphragm carburetor with integral fuel pump

Fuel tank capacity: 1,700 cm³ (1.7 l)

Blowing performance

Blowing force:	28 N
Air speed:	83 m/s
Air flow rate:	1,090 m3/h
Maximum air velocity:	99 m/s
Maximum air flow rate (without blower unit):	1,430 m3/h

Weight

BR 450:	10,6 kg
BR 450 C:	11.5 kg

Maintenance and Repairs

Users of this machine may only carry out the maintenance and service work described in this user manual. All other repairs must be carried out by a servicing dealer.

STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer. STIHL dealers are regularly given the opportunity to attend training courses and are supplied with the necessary technical information.

When repairing the machine, only use replacement parts which have been approved by STIHL for this power tool or are technically identical. Only use highquality replacement parts in order to avoid the risk of accidents and damage to the machine.

STIHL recommends the use of original STIHL replacement parts.

Original STIHL parts can be identified by the STIHL part number, the logo and the STIHL parts symbol (the symbol may appear alone on small parts).

Warranty

If you have any questions regarding your warranty rights and responsibilities, please contact a STIHL customer service representative at www.stihl.ca

Where to make a Claim for Warranty Service
Bring the product to any authorized STIHL servicing dealer and present the signed warranty card.

Documents / Resources

References

• STIHL CANADA | STIHL

Download manual

Here you can download full pdf version of manual, it may contain additional safety instructions, warranty information, FCC rules, etc.

Download Stihl BR 450, BR 450 C Manual