Stihl SP 451, SP 481 Instruction Manual

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STIHL SP 451, 481 Instruction Manual

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Original Instruction ManualPrinted on chlorine-free paper

Printing inks contain vegetable oils, paper can be recycled.

0458-418-0121-A. M0-125.A11.DDS.

0000001685_005_GB

SP 451, SP 481

English

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Contents

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.

Your

Hans Peter Stihl

Guide to Using this Manual 2 Safety Precautions and Working

Techniques 2 Using the Unit 6 Assembling the Unit 7 Adjusting the Throttle Cable 8 Fuel 8 Fueling 9 Starting / Stopping the Engine 10 Operating Instructions 13 Fitting the Harness 13 Transporting the Unit 15 Cleaning the Air Filter 16 Adjusting the Carburetor 16 Spark Plug 17 Engine Running Behavior 18 Replacing the Starter Rope and

Rewind Spring 19 Storing the Machine 20 Inspection and Maintenance by

User 21 Inspections and Maintenance by

Dealer 22 Maintenance and Care 23 Minimize Wear and Avoid Damage 25 Main Parts 26 Specifications 27 Special Accessories 28 Maintenance and Repairs 28 EC Declaration of Conformity 28 Quality Certification 29

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Pictograms

All the pictograms attached to the machine are shown and explained in this manual.

Symbols in text

Engineering improvements

STIHL's philosophy is to continually improve all of its products. For this reason we may modify the design, engineering and appearance of our products periodically.

Therefore, some changes, modifications and improvements may not be covered in this manual.

Observe all applicable local safety regulations, standards and ordinances.

If you have not used this type of power tool before: Have your dealer or other experienced user show you how to operate your power tool or attend a special course in its operation.

Minors should never be allowed to use a power tool.

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

When the power tool is not in use, shut it off so that 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 than 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.

To operate the 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 tool.

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

Use the special harvester only for shaking small trees, branches, bushes and shrubs.

Do not use your harvester for any other purpose since this may result in accidents.

Only mount tools and accessories that are explicity 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

Guide to Using this Manual

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.

Safety Precautions and Working Techniques

Some special safety precautions must be observed when working with this harvester because of the very high oscillating speed of the hook.

It is important you read and understand the instruction manual before using your power tool for the first time and keep the manual in a safe place for future reference. Non-observance of the safety precautions may result in serious or even fatal injury.

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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. They are specifically designed to match your model and meet your performance requirements.

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

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

Clothing and Equipment

Wear proper protective clothing and equipment.

Avoid clothing that could get caught on branches or brush or moving parts of the machine. Do not wear a scarf, necktie or jewelry. Tie up and confine long hair (e.g. with a hair net, cap, hard hat, etc.).

Warning! A face shield alone does not provide adequate eye protection.

Wear hearing protection, e.g. earplugs or ear muffs.

Transporting the Power Tool

Always stop the engine.

Carry the unit suspended from the harness.

Transporting in a vehicle: Properly secure your power tool to prevent turnover, fuel spillage and damage.

Fueling

Always shut off the engine before refueling.

Do not fuel a hot engine – fuel may spill and cause a fire.

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 wellventilated areas. If you spill fuel, wipe the machine immediately – if fuel gets on your clothing, change immediately.

This reduces the risk of unit vibrations causing the fuel cap to loosen or come off and spill quantities of fuel.

Check for leakage. To reduce the risk of serious of fatal burn injuries, 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 – refer to appropriate chapters in the instruction manual.

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.

Wear steel-toed safety boots with non-slip soles.

Wear a safety hard hat where there is a danger of head injuries from falling objects. Wear a face shield and safety glasses.

Wear heavy-duty gloves, preferably made of leather.

4902BA001 KN

Gasoline is an extremely flammable fuel. Keep clear of naked

flames. Do not spill any fuel – do not smoke.

After fueling, tighten down the screw-type fuel cap as securely as possible.

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– Slide control / stop switch must

move easily to STOP or 0.

– Smooth action of throttle trigger and

throttle trigger interlock – throttle trigger must return automatically to idle position.

– Check that the spark plug boot is

secure – a loose boot may cause arcing that could ignite combustible fumes and cause a fire.

– Keep the handles dry and clean –

free from oil and dirt – for safe control of the power tool.

– Hook with rubber element: Properly

mounted and in good condition.

– Never attempt to modify the controls

or the safety devices in any way.

– Adjust the harness to suit your

height and reach – see "Fitting the Harness".

To reduce the risk of personal injury, do not operate your power tool if it is damaged or not properly assembled.

For emergencies: Practise removing and putting down the machine as you would in an emergency. To avoid damage, do not throw the machine to the ground when practising – see also "Fitting the Harness".

Starting the engine

Start the engine at least 3 meters from the fueling spot, outdoors only.

Place the unit on firm ground in an open area. Make sure you have good balance and secure footing. Hold the unit securely. The hook must be clear of the

ground and all other obstacles because it may begin to run when the engine starts.

Your harvester is a one-person unit. To reduce the risk of injury from thrown objects or contact with the shaft and hook, do not allow other persons within a radius of 10 meters of your own position – even when starting.

Do not drop start the power tool – start the engine as described in the instruction manual.

Note that the hook continues to run for a short period after you let go of the throttle trigger (flywheel effect).

Make sure the idle speed setting is correct. The hook must not move when the engine is idling with the throttle trigger released.

Check and correct the idle speed setting at regular intervals. If the hook still moves, have your dealer check your machine and make proper adjustments or repairs. STIHL recommends a STIHL servicing dealer.

To reduce the risk of fire, keep hot exhaust gases and hot muffler away from easily combustible materials (e.g. wood chips, bark, dry grass, fuel).

Holding and Controlling the Power Tool

Always hold the unit on the right-hand side of your body with both hands on the handles.

Left hand on the front handle, right hand on the control handle, even if you are left-handed.

Make sure you always have good balance and secure footing.

During Operation

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.

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 operate the power tool in enclosed or poorly ventilated locations.

4902BA002 KN

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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.

The dusts, vapor and smoke produced during operation may be dangerous to health. If dust levels are very high, wear a suitable respirator.

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.

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

Do not work alone – keep within calling distance of others in case help is needed.

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

Do not operate your power tool in the starting throttle position. Engine speed cannot be controlled with the throttle trigger in this position.

Opening the throttle while the hook is blocked increases the load and reduces engine speed. The clutch then slips continuously and this causes overheating and damage to important components (e.g. clutch, polymer

housing components) – and this can increase the risk of injury from the hook moving while the engine is idling.

To reduce the risk of personal injury from falling branches, fruit, etc., do not allow any other persons within a radius of 15 meters of your own position while you are working.

Special care must be taken when working in difficult, over-grown terrain.

Take special care in slippery conditions – damp, slopes, fruit on the ground and on uneven ground.

Watch out for obstacles: Watch out for tree stumps, roots and fallen fruit to avoid stumbling.

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

Before starting work, check the safety devices for damage or wear. Always replace damaged parts. Never operate your power tool with damaged safety devices.

Check the hook, rubber element and shaft at regular short intervals or immediately if there is a noticeable change in the tool's behavior:

– Shut off the engine and hold the unit

firmly.

– Check condition – look for cracks.

– Replace damaged parts

immediately, even if they have only superficial cracks.

To reduce the risk of unintentional engine start and injury, always shut off the engine before replacing the hook and shaft.

Do not continue using or attempt to repair a damaged or cracked hook by welding or straightening.

After finishing work or before leaving the unit unattended: Shut off the engine.

Vibrations

Recommendation: Several persons should share the day's work with the harvester by rotating at regular intervals.

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

The period of usage is prolonged by:

– Hand protection (wearing warm

gloves)

– Work breaks

The period of usage is shortened by:

– Any personal tendency to suffer

from poor circulation (symptoms: frequently cold fingers, tingling sensations).

– Low outside temperatures.

– The force with which the handles

are held (a tight grip restricts circulation).

Seek medical advice immediately if any of the following symptoms appear:

The function of this harvester causes vibrations. Some of these vibrations are transmitted to the handles. Therefore, the permissible period of daily usage for one operator is restricted.

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– Fingers turning white – especially in

cold weather.

– Tingling sensations and numbness

in fingers (after using the machine).

– Constant pains in muscles or joints.

– Difficulty gripping or holding small

objects, such as screws, nails, etc.

Operators with the above symptoms should not use the machine until further notice.

An aid to calculating the daily exposure to vibrations can be found on www.stihl.com/vib. Dealers can also provide information on daily exposure to vibrations. STIHL recommends you consult a STIHL servicing dealer in this respect.

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 unless the slide control / stop switch is on STOP or 0 since there is otherwise a risk of fire from uncontained sparking.

To reduce the risk of fire, do not service or store your machine near open flames.

Check the fuel filler cap for leaks at regular 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.

Preparations

N Start the engine – see

"Starting / Stopping the Engine".

N Put on the harness – see "Fitting the

Harness".

N Attach the hook (1) to a branch –

rotate the shaft (2) to turn the hook to the required position.

Using the Unit

Do not operate the harvester without the harness.

4902BA003 KN

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Working Position

N With the harvester suspended from

the harness (3), hold the control handle with your right hand and hold and control the unit with your left hand on the front handle (4).

N Open the throttle and begin work

Mounting the Shaft

N Place the powerhead on a clean

and flat surface so that it is resting on the guard plate and the machine support (under the front handle).

N Place the shaft (1) in front of the

powerhead and check that both parts form a straight line.

N Push back the hand guard (2) to

expose the thread (3) on the pushrod.

N Hold the hand guard in this position

and screw the shaft (1) onto the pushrod's thread by hand – as far as stop.

N Position the 27mm open-end

wrench on the pushrod's hexagon.

N Position the 34mm open-end

wrench on the shaft's hexagon.

Do not grip the shaft during operation because its movements will otherwise be transmitted directly to your body – the anitivibration system will be bypassed – see also section on "Vibrations" in "Safety Precautions and Working Techniques".

4902BA004 KN

Assembling the Unit

Make sure the ends of the shaft and pushrod are clean.

4902BA005 KN

4902BA006 KN

4902BA007 KN

SW 27

SW 34

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N Hold the pushrod steady with the

27mm wrench and tighten down the shaft firmly.

Removing the Shaft

The shaft can be removed again to save space when transporting the machine. See chapter on "Transporting the Machine".

Attaching the Harness

N Attach the harness to the machine

and put it on – see "Putting on the Harness".

A properly adjusted throttle cable is the precondition for correct operation in the starting throttle, idle and full throttle positions.

N Adjust the throttle cable only when

the unit is completely and properly assembled.

N Use a suitable tool to push the slide

to the end of the slot (see illustration).

N Press down the throttle trigger

lockout (1) and squeeze the throttle trigger (2) (full throttle) – this sets the throttle cable correctly.

Your engine requires a mixture of gasoline and engine oil.

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 STIHL engines and guarantees a long engine life.

MotoMix is not available in all markets.

Mixing Fuel

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.

4902BA008 KN

SW 27

SW 34

Adjusting the Throttle Cable

4902BA009 KN

4902BA010 KN

Fuel

For health reasons, avoid direct skin contact with gasoline and avoid inhaling gasoline vapor.

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.

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Engine Oil

Use only quality two-stroke engine oil. We recommend STIHL two-stroke

engine oil since it is specially formulated for use in STIHL 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 watercooled 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

Examples

N Use a canister approved for storing

fuel. Pour oil into canister first, then add gasoline and mix thoroughly.

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.

N Thoroughly shake the mixture in the

canister before fueling your machine.

N Clean the fuel tank and canister

from time to time.

Dispose of remaining fuel and cleaning fluid properly in accordance with local regulations and environmental requirements.

Preparations

N Before fueling, clean the filler cap

and the area around it to ensure that no dirt falls into the tank.

N Position the machine so that the

filler cap is facing up.

Filling up with fuel

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

A few tankfuls of leaded gasoline will greatly reduce the efficiency of the catalytic converter.

Gasoline STIHL engine oil 50:1 Liters Liters (ml) 10,02(20) 5 0,10 (100) 10 0,20 (200) 15 0,30 (300) 20 0,40 (400) 25 0,50 (500)

Other brand-name two-stroke engine oils: 25 parts gasoline to 1 part oil

Pressure may build up in the canister – open it carefully.

Fueling

256BA060 KN

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N Open the filler cap. N Filling up with fuel N Close the filler cap.

Changing the Fuel Pickup Body

Change the fuel pickup body every year: N Open the filler cap and drain the fuel

tank.

N Use a hook to pull the fuel pickup

body out of the tank and take it off the hose.

N Push the new pickup body into the

hose.

N Place the pickup body in the tank. N Fill up with fuel and close the filler

cap.

Control Handle

Controls

1 Throttle trigger lockout 2 Throttle trigger 3 Slide control

Positions of slide control

4STOP-0 – engine off – the ignition is

switched off

5 F – normal run position – the engine

is running or can start

6 START – the ignition is switched on

– the engine can start

After fueling, tighten down the filler cap as securely as possible by hand.

Do not kink the fuel hose – do not use any sharp or pointed tools.

412BA060 KN

Starting / Stopping the Engine

START

STOP-

STOP

4902BA011 KN

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Symbol on slide control 7 h – stop symbol and arrow. To stop

the engine, push the slide control in the direction of the arrow on the stop symbol (h) to STOP-0.

Starting

N Press down the trigger lockout lever

and squeeze the throttle trigger.

N Hold both levers in this position. N Move the slide control to START

and hold it there.

N Now release the throttle trigger,

slide control and trigger lockout in that order. This is the starting throttle position.

N Set the choke knob (8):

N Press the fuel pump bulb (9) at least

five times – even if the bulb is already filled with fuel.

N Press in the decompression valve

button (10) before each starting

attempt.

Cranking

N Place the unit on the ground: It must

rest on the guard plate on the underside of the powerhead and the machine support under the front

handle. Check that the hook is not touching the ground of any other obstacles.

N Make sure you have a firm footing. N Hold the unit with your left hand and

press it down firmly.

N Pull the starter grip slowly with your

right hand until you feel it engage and then give it a brisk strong pull.

N Do not let the starter grip snap back.

Guide it slowly back into the housing so that the starter rope can rewind properly.

N Continue cranking until engine fires.

When the engine begins to fire:

N Turn the choke knob to e. N Press in button to open the

decompression valve.

N Continue cranking until the engine

runs.

g If the engine is cold e for warm start – also use this posi-

tion if the engine has been running but is still cold.

250BA018 KN

4902BA012 KN

4902BA013 KN

4902BA014 KN

Do not pull out the starter rope all the way – it might otherwise break.

4902BA015 KN

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As soon as the engine runs

N Blip the throttle trigger

immediately. The slide control moves to the normal run position F – and the engine settles down to idle speed.

Your machine is now ready for operation.

Stopping the Engine

N Push the slide control in the

direction of the arrow on the stop symbol (h) to STOP-0.

At very low outside temperatures:

As soon as the engine runs: N Blip the throttle trigger to disengage

the starting throttle position. The slide control moves to the normal run position (F) – and the engine settles down to idle speed.

N Open the throttle slightly. N Warm up the engine briefly.

If the engine does not start

Choke knob

If you did not turn the choke knob to e quickly enough after the engine began to fire, the combustion chamber is flooded.

N Turn the choke knob to e. N Select the starting throttle

position.

N Start the engine by pulling the

starter rope briskly – 10 to 20 pulls may be necessary.

If the engine still does not start

N Move the slide control to STOP-0. N Remove the spark plug – see

"Spark Plug".

N Dry the spark plug. N Open the throttle wide and hold it

that position.

N Crank the engine several times with

the starter to clear the combustion chamber.

N Refit the spark plug – see "Spark

Plug".

N Connect the spark plug boot (press

it down firmly).

N Move the slide control to START. N Set the choke knob to e – even if

the engine is cold.

N Start the engine.

Throttle cable adjustment

N Check adjustment of throttle cable –

see chapter on "Adjusting the Throttle Cable".

Fuel tank run until completely dry

N After refueling, press the fuel pump

bulb at least five times – even if the bulb is filled with fuel.

N Set the choke knob according to

engine temperature.

N Now start the engine.

Make sure the carburetor is correctly adjusted. The hook must not move when the engine is idling.

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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 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 protects enginemounted components (ignition, carburetor) from thermal overload.

After Finishing Work

Storing for a short period: Wait for the engine to cool down. Empty the fuel tank and keep the machine in a dry place, well away from sources of ignition, until you need it again. For longer out-ofservice perionds – see "Storing the Machine".

Using a harness

STIHL recommends you use the harness supplied with the machine because it is specifically designed to match the machine and the application, and ensure ergonomic operation.

Putting on the harness and attaching it to the machine

N Put your left arm through the

opening in the harness (1).

N Place the harness (1) on your left

shoulder.

– The carabiner (2) is on the left side

of your body.

– The carrying loop (3) is on the left

side of your body.

N Squat down on the left-hand side of

the machine to save your back when lifting the machine.

N Attach the carabiner (2) to the rear

carrying ring (4).

N Engage the loop (3) in the front hook

(5) by pulling the loop firmly over the locking bar (6).

Operating Instructions Fitting the Harness

4902BA016 KN

4902BA017 KN

4902BA018 KN

4902BA019 KN

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N Straighten out the harness and

straps.

N Stand upright from the squatting

position and lift the machine at the same time – it hangs at the right side of your body.

Adjusting the harness straps

Adjust the length of the straps with the sliding adjusters (arrows).

Tightening the harness straps

N Pull the end of the strap down to

tighten the strap.

Loosening the harness straps

N Press the sliding adjuster down to

loosen the strap.

N Adjust the length of the straps so

that the machine is at an angle with the hook pointing slightly up.

Putting the machine down and disengaging the harness

N Squat down and put the machine on

the ground.

N Slip the harness off your left

shoulder and your arm.

4902BA020 KN

4902BA021 KN

4902BA022 KN

4902BA023 KN

4902BA024 KN

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N Disconnect the carabiner (2) from

the rear carrying ring (4).

N Pull the loop (3) out of the front hook

by pulling it firmly over the locking bar (6).

Throwing off the machine in an emergency

N Quickly pull the loop out of the front

hook.

N Slip the harness off your left

shoulder and your arm.

N Let the machine and harness fall to

the ground.

The shaft with hook can be removed to save space when transporting the machine.

Removing the Harness

N If necessary, disconnect the

harness from the machine – see "Fitting the Harness".

Removing the Shaft

N Put the machine down on a clean

and level surface so that it rests on the guard plate and the machine support (under the front handle). Make sure the hook is not touching the ground or any other obstacles.

N Push back the hand guard (1) to

expose the hexagon ends of the shaft (2) and pushrod (3).

N First position the 27mm open-end

wrench on the pushrod's hexagon.

N Position the 34mm open-end

wrench on the shaft's hexagon.

N Loosen and unscrew the shaft from

the pushrod's thread.

Mounting the Shaft

N Refit the shaft – see "Assembling

the Unit".

Attaching the Harness

N Attach the harness to the machine

and put it on – see "Fitting the Harness".

The machine and harness must be quickly thrown off in an emergency. To do this:

4902BA025 KN

4902BA026 KN

Transporting the Unit

4902BA027 KN

Make sure the ends of the shaft and pushrod are clean.

4902BA028 KN

SW 27

SW 34

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

If there is a noticeable loss of engine power

N Turn the choke knob to g N Loosen the screw (1). N Remove the filter cover (2). N Clean away loose dirt from around

the filter and inside the filter cover.

N Remove and check the filter

element (3) – replace if dirty or damaged.

N Install the filter element in the filter

cover.

N Fit the filter cover.

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 adjust the high speed and low speed screws within fine limits.

Standard Setting

N Stopping the Engine N Check the air filter and replace it if

necessary.

N Check that the throttle cable is

properly adjusted – readjust if necessary – see chapter on "Adjusting the Throttle Cable".

N Turn the high speed screw (H)

counterclockwise as far as stop (no more than 3/4 turn).

N Turn the low speed screw (L)

carefully clockwise as far as stop, then turn it back 1 full turn.

N Start and warm up the engine if

necessary.

N Adjust idle speed with the idle speed

screw (LA) so that the hook does not move.

Fine Tuning

A slight correction of the setting of the high speed screw (H) may be necessary if engine power is not satisfactory when operating at high altitude or at sea level.

Cleaning the Air Filter

256BA062 KN

Adjusting the Carburetor

Adjustments may be performed only when the machine is completely and securely assembled.

412BA076 KN

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N Turn the high speed screw (H)

about one eighth of a turn for every 1000m change in altitude.

N Carry out standard setting on low

speed screw (L).

N Warm up the engine for about 3

minutes.

N Open the throttle wide.

At high altitude

N Turn the high speed screw (H)

clockwise (leaner), no further than stop, until there is no further noticeable increase in engine speed.

At sea level

N Turn the high speed screw (H)

counterclockwise (richer), no further than stop, until there is no further noticeable increase in engine speed.

It is possible that maximum engine speed may be reached with the standard setting in each case.

Adjusting Idle Speed

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

N Warm up the engine for about 3

minutes.

Engine stops while idling

N Turn the idle speed screw (LA)

slowly clockwise until the engine runs smoothly – the hook must not move.

Hook runs when engine is idling

N Turn the idle speed screw (LA)

counterclockwise until the hook stops moving and then rotate the screw another 1/2 to 1 turn in the same direction.

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

Idle setting is too lean N 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 N Turn the low speed screw (L)

clockwise, no further than stop, until the engine runs and accelerates smoothly.

N If the engine is down on power,

difficult to start or runs poorly at idle speed, first check the spark plug.

N 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

N Move the slide control to STOP-0

(h).

N Pull off the spark plug boot (1). N Unscrew the spark plug.

If the hook continues moving when the engine is idling, have your power tool checked and repaired by your servicing dealer.

Spark Plug

271BA073 KN

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Checking the spark plug

N Clean dirty spark plug. N Check electrode gap (A) and

readjust if necessary – see "Specifications".

N 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.

Installing the spark plug

N Screw the spark plug (3) into the

cylinder and fit the boot (2) (press it down firmly).

If engine running behavior is unsatisfactory even though the air filter is clean and the carburetor and throttle cable are properly adjusted, the cause may be the muffler.

Have the muffler checked by a servicing dealer for contamination (carbonization).

STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer.

If the spark plug comes with a detachable adapter nut (1), screw the adapter onto the thread and tighten it down firmly to reduce the risk of arcing and fire.

000BA039 KN

000BA045 KN

002BA178 KN

Engine Running Behavior

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Removing the Fan Housing

N Take out the screws (1). N Remove the fan housing.

Replacing the Starter Rope

N Remove the spring clip (2). N Carefully remove the rope rotor with

washer (3) and pawl (4).

N Pry the cap (5) out of the grip. N Remove the remaining rope from

the rotor and starter grip.

N Tie a simple overhand knot in the

new rope and then thread it through the top of the grip and the rope bushing (6).

N Refit the cap in the grip.

N Pull the rope through the rotor and

secure it with a simple overhand knot.

N Coat rope rotor bearing bore with

non-resinous oil – see "Special Accessories".

N Slip the rotor over the starter post –

turn it back and forth to engage the anchor loop of the rewind spring.

N Fit the pawl (4). N Fit the washer (3). N Push the spring clip (2) into position

– it must point counterclockwise as shown and engage the pawl's peg.

Replacing the Starter Rope and Rewind Spring

The rewind spring may pop out and uncoil during this operation – take care to avoid the risk of injury.

256BA075 KN

256BA032 KN

256BA033 KN

256BA034 KN

256BA032 KN

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Tensioning the Rewind Spring

N Make a loop in the unwound starter

rope and use it to turn the rope rotor six full revolutions counterclockwise.

N Hold the rotor steady. N Pull out and straighten the twisted

rope.

N Let go of the rotor. N Release the rope slowly so that it

winds onto the rotor.

The starter grip must sit firmly in the rope bushing. If the grip droops to one side: Add one more turn on the rope rotor to increase spring tension.

N Take one turn of the rope off the

rotor.

N Fit the fan housing.

Replacing a Broken Rewind Spring

N Remove the rope rotor as described

in "Replacing the Starter Rope".

N Take out the screws (7). N Remove the spring housing and

pieces of spring.

N Lubricate the new, ready-to-fit

replacement spring in the new spring housing with a few drops of resin-free oil – see "Special Accessories".

N Place the replacement spring with

spring housing in position – bottom plate facing up.

If the spring pops out of the housing during installation: Refit it clockwise, starting outside and working inwards.

N Fit the screws. N Refit the rope rotor as described in

"Replacing the Starter Rope".

N Tension the rewind spring. N Fit the fan housing.

For periods of 3 months or longer N Drain and clean the fuel tank in a

well ventilated area.

N Dispose of fuel properly in

accordance with local environmental requirements.

N Run the engine until the carburetor

is dry – this helps prevent the carburetor diaphragms sticking together.

N Thoroughly clean the machine –

pay special attention to the cylinder fins and air filter.

N Store the machine in a dry, high or

locked location, – out of the reach of children and other unauthorized persons.

When the starter rope is fully extended it must still be possible to rotate the rotor another one and a half turns. If this is not the case, the spring is overtensioned and could break.

427BA016 KN

The bits of the spring may still be under tension and could fly apart when you remove the rope rotor and spring housing. To reduce the risk of injury, wear face protection and work gloves.

271BA053 KN

Storing the Machine

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Visual Inspection

N Visually inspect the whole machine

before each use and after every refueling stop.

Screws and Nuts

N Check all accessible screws and

nuts (not the carburetor adjusting screws) about every 25 hours of operation.

N Check the screw union of the shaft

and pushrod in the hand guard after every refueling stop – see "Assembling the Unit".

Replacing the Rubber Element on the Hook

Removing the rubber element

N Use a suitable tool to pry the clips

(1) out of the hook (2).

N Do not re-use damaged or bent

clips. Always fit new ones.

N Cut the worn rubber element (3) so

that it can be easily pulled off the hook.

Installing the rubber element

N Coat the new rubber element (3)

and the hook (2) thoroughly with STIHL press fluid OH 723 – see "Special Accessories".

N Push the hook into the rubber

element as shown.

N Insert the clips (1) in the rubber

element and press them home as far as stop.

Inspection and Maintenance by User

4902BA034 KN

4902BA035 KN

4902BA036 KN

4902BA037 KN

4902BA038 KN

4902BA039 KN

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Correct position of clips

Lubricating the Pushrod

N Check the grease level regularly –

about every 150 hours of operation.

N Unscrew the filler plug (1). If no

grease can be seen on the inside of the filler plug, screw the tube (2) of STIHL gear lubricant for brushcutters (special accessory) into the filler hole.

N Squeeze grease into the housing.

N Remove the tube of grease (2). N Refit the filler plug and tighten it

down firmly.

Maintenance Work

STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer.

Antivibration System (AV system)

Rubber elements are installed in the machine to reduce vibrations.

There are two rubber elements (1) in front of and behind the control handle (2). A further rubber element (3) is installed in the machine support (4).

N Have the rubber elements checked

at least after every 50 hours of operation, or if there any visible signs of wear and/or if there is a noticeable increase in vibrations.

Do not completely fill the housing with grease.

4902BA040 KN

4902BA041 KN

Inspections and Maintenance by Dealer

4902BA042 KN

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Maintenance and Care

The following intervals apply to normal operating conditions only. If your daily working time is longer or operating conditions are difficult (very dusty work area, etc.), shorten the specified intervals accordingly.

before starting work

after finishing work or daily

after each refueling stop

weekly

monthly

every 12 months

if problem

if damaged

if required

Complete machine

Visual inspection (condition, leaks) XX

Clean X

Control handle Check operation XX

Air filter

Clean XX

Replace X

Pickup body in fuel tank

Check X

Replace XXX

Fuel tank Clean XXX

Carburetor

Check idle adjustment – the hook must not move

Adjusting Idle Speed X

Spark plug

Adjust electrode gap X

Replace after every 100 operating hours

Cooling inlets

Visual Inspection X

Clean X

Spark arresting screen

in muffler

Check

Clean or replace

All accessible screws and nuts (not adjusting screws)

Retighten X

Antivibration elements

Check XXX

Replace

Hook with rubber element

Visual Inspection XX

Check tightness XX

Replace XX

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All accessible screws and nuts (not adjusting screws)

Retighten X

Pushrod lubrication

Check XXX

Replenish X

Safety labels Replace X

not in all versions, market-specific

STIHL recommends that this work be done by a STIHL servicing dealer

before starting work

after finishing work or daily

after each refueling stop

weekly

monthly

every 12 months

if problem

if damaged

if required

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Observing the instructions in this manual helps reduce the risk of unnecessary wear and damage to the power tool.

The power tool must be operated, maintained and stored with the due care and attention described in this owner's manual.

The user is responsible for all damage caused by non-observance of the safety precautions, operating and maintenance instructions in this manual. This includes in particular:

– Alterations or modifications to the

product not approved by STIHL.

– Using tools or accessories which

are neither approved or suitable for the product or are of a poor quality.

– Using the product for purposes for

which it was not designed.

– Using the product for sports or

competitive events.

– Consequential damage caused by

continuing to use the product with defective components.

Maintenance Work

All the operations described in the "Maintenance Chart" must be performed on a regular basis. If these maintenance operations cannot be performed by the owner, they should be performed by a servicing dealer.

STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL

servicing dealer. STIHL dealers are regularly given the opportunity to attend training courses and are supplied with the necessary technical information.

If these maintenance operations are not carried out as specified, the user assumes responsibility for any damage that may occur. Among other parts, this includes:

– Damage to the engine due to

neglect or deficient maintenance (e.g. air and fuel filters), incorrect carburetor adjustment or inadequate cleaning of cooling air inlets (intake ports, cylinder fins).

– Corrosion and other consequential

damage resulting from improper storage.

– Damage to the machine resulting

from the use of poor quality replacement parts.

Parts Subject to Wear and Tear

Some parts of the power tool are subject to normal wear and tear even during regular operation in accordance with instructions and, depending on the type and duration of use, have to be replaced in good time. Among other parts, this includes:

– Rubber element on hook

– Shaft with hook

– Gearbox

– Clutch

– Filters (air, fuel)

– Rewind starter

– Spark plug

– Components of antivibration system

Minimize Wear and Avoid Damage

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1 Hook 2 Shaft 3 Hand guard 4 Handle 5 Machine support 6 Hook 7 Carrying ring 8 Fuel pump 9 Choke knob 10 Filter cover 11 Fuel tank 12 Guard plate 13 Throttle cable 14 Control handle 15 Throttle trigger lockout 16 Slide control 17 Throttle trigger 18 Filler plug 19 Pushrod 20 Fuel filler cap 21 Carburetor adjusting screws 22 Starter grip 23 Decompression valve 24 Spark plug boot 25 Muffler (with spark arrestor in some

markets)

26 Harness # Serial number

Main Parts

7 8

4902BA043 KN

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Engine

STIHL single cylinder two-stroke engine

SP 451

SP 481

Ignition System

Electronic magneto ignition

Fuel System

All position diaphragm carburetor with integral fuel pump

Weight

Hook

Length

Noise and Vibration Data

Noise measurements include idling and rated maximum speed, vibration measurements idling and full load with the same duration of exposure in each case.

For further details on compliance with Vibration Directive 2002/44/EC see www.stihl.com/vib/

Tool: Hook

Sound pressure level L

peq

ISO 11201

Sound power level L

weq

to ISO 3744

Vibration measurement a

hv,eq

ISO 20643

The K-factor in accordance with Directive 2006/42/EC is 2.5 dB(A) for the sound pressure level and sound power level; the K-factor in accordance with Directive 2006/42/EC is 2.0 m/s

for the vibration measurement.

REACH

REACH is an EC regulation and stands for the Registration, Evaluation, Authorisation and Restriction of Chemical substances.

For information on compliance with the REACH regulation (EC) No. 1907/2006 see www.stihl.com/reach.

Specifications

Displacement: 44.3 cm

Bore: 42 mm Stroke: 32 mm Engine power to

ISO 8893:

2.1 kW (2.9 HP) at 9,000 rpm

Cut-off speed (rated): 12,500 rpm

Idle speed: 2,800 rpm

Displacement: 48.7 cm

Bore: 44 mm Stroke: 32 mm Engine power to

ISO 8893:

2.2 kW (3.0 HP) at 9,000 rpm

Cut-off speed (rated): 12,500 rpm

Idle speed: 2,800 rpm

Spark plug (resistor type):

Bosch WSR 6 F, NGK BPMR 7 A

Electrode gap: 0.5 mm

Fuel tank capacity: 0.67 l

Overall weight, dry, with harness: 13.9 kg

Powerhead, dry: 12.8 kg Shaft with hook: 1.1 kg

Opening: 42 mm Stroke: 45 mm Strokes per minute at

12,500 rpm: 3328

Overall length: 2865 mm Shaft with hook: 1860 mm

SP 451: 102 dB(A) SP 481: 102 dB(A)

SP 451: 113 dB(A) SP 481: 113 dB(A)

Handle, left

Handle, right

SP 451: 5.7 m/s

5.7 m/s

SP 481: 5.7 m/s

5.7 m/s

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– Shaft with hook

– Rubber element for hook

– STIHL Press Fluid OH

0781 957 9000

– Open-end wrench, 27mm

– Open-end wrench, 34mm

– Combination wrench

– Carburetor screwdriver

– Harness

– STIHL ElastoStart (starter rope with

grip)

– STIHL gear lubricant for

brushcutters

– STIHL filler nozzle for fuels

– Special resin-free lubricating oil

Contact your STIHL dealer for more information on these and other special accessories.

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.

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 K (the symbol may appear alone on small parts).

ANDREAS STIHL AG & Co. KG Badstr. 115 D-71336 Waiblingen

confirms that the machine described below

conforms to the specifications of Directives 2006/42/EC and 2004/108/EC and has been developed and manufactured in compliance with the following standards:.

EN ISO 12100, EN 55012, EN 61000-6-1

Technical documents deposited at:

ANDREAS STIHL AG & Co. KG Produktzulassung (Product Licensing)

The year of manufacture and serial number are applied to the product.

Special Accessories Maintenance and Repairs EC Declaration of

Conformity

Type: Special harvester Make: STIHL Model: SP 451

SP 481 Serial identification: 4246 Displacement SP 451: 44.3 cm

SP 481: 48.7 cm

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Done at Waiblingen, 01.03.2010

ANDREAS STIHL AG & Co. KG

Elsner

Director Group Product Management

All STIHL products comply with the highest quality standards.

An independent organization has certified that all products manufactured by STIHL meet the strict requirements of the ISO 9001 standard for quality management systems in terms of product development, materials purchasing, production, assembly, documentation and customer service.

Quality Certification

000BA025 LÄ

Page 32

www.stihl.com

*04584180121A*

0458-418-0121-A

englisch