STIHL FS 45 Brushcutter Instruction Manual

Contents

1. Guide to Using this Manual
2. Safety Precautions and Working Techniques
3. Approved Combinations of Cutting Attachment, Deflector, Handle and Harness
4. Mounting the Loop Handle
5. Mounting the Deflector
6. Mounting the Cutting Attachment
7. Fuel
8. Fueling
9. Starting / Stopping the Engine
10. Operating Instructions
11. Cleaning the Air Filter
12. Adjusting the Carburetor
13. Spark Plug
14. Engine Running Behavior
15. Storing the Machine
16. Maintaining the Mowing Head
17. Inspections and Maintenance by Dealer
18. Maintenance and Care
19. Main Parts
20. Specifications
21. Maintenance and Repairs
22. Disposal
23. EC Declaration of Conformity

1 Guide to Using this Manual

1.1 Pictograms

The meanings of the pictograms attached to the machine are explained in this manual.

Depending on the model concerned, the following pictograms may be attached to your machine:

• Fuel tank; fuel mixture of gasoline and engine oil
• Operate decompression valve ?️
• Manual fuel pump ⛽
• Operate manual fuel pump
• Tube of grease ?
• Intake air: Summer operation ☀️
• Intake air: Winter operation ❄️
• Handle heating ?

1.2 Symbols in text

WARNING: Warning where there is a risk of an accident or personal injury or serious damage to property.

NOTICE: Caution where there is a risk of damaging the machine or its individual components.

1.3 Engineering improvements

STIHL's philosophy is to continually improve all of its products. For this reason, STIHL may modify the design, engineering, and appearance of its products periodically. Therefore, some changes, modifications, and improvements may not be covered in this manual.

2 Safety Precautions and Working Techniques

Some special safety precautions must be observed to reduce the risk of personal injury when operating this power tool because of the very high speed of its cutting attachment.

It is important to read and understand the User Manual before commissioning and keep it in a safe place for future reference. Non-compliance with the User Manual may cause serious or even fatal injury.

Observe all applicable local safety regulations, e.g., by trade organizations, social insurance institutions, labor safety authorities, etc.

If you have never used a power tool before:

• Have your dealer or other experienced user show you how to operate your machine or attend a special course to learn how to operate it.

Minors should never be allowed to use the machine – except for apprentices over the age of 16 when working under supervision.

Children, animals, and bystanders must not be allowed near the machine.

When not using the machine, it must be laid down in such a way that it does not endanger anyone. Ensure that the machine cannot be used without authorization.

The user is responsible for accidents or risks involving third parties or their property.

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

The use of machines that emit noise may be limited to certain hours of the day as specified by national and/or regional or local regulations.

Anyone operating the machine must be well rested, in good physical health, and in good mental condition.

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

If you have a pacemaker: The ignition system of your machine produces an electromagnetic field of very low intensity. This field may interfere with some pacemakers. STIHL recommends that persons with pacemakers consult their physician and the pacemaker manufacturer to reduce any health risk.

Anyone who has consumed alcohol or drugs or medicines affecting their ability to react must not operate a power tool.

Depending on the cutting attachment fitted, use your trimmer only for cutting grass, wild growth, and similar materials.

The power tool must not be used for any other purpose because of the increased risk of accidents and damage to the machine. Never attempt to modify your power tool in any way, since this may result in accidents or damage to the machine.

Only use cutting attachments and accessories that are explicitly approved for this power tool model by STIHL or are technically identical. If you have any questions in this respect, consult your 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 tools and accessories. They are specifically designed to match the product and meet your performance requirements.

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

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

The guard provided with your machine may not protect the operator from all foreign objects (gravel, glass, wire, etc.) ejected by the revolving cutting attachment. Ejected objects may also ricochet and strike the operator.

2.1 Clothing and equipment

Wear proper protective clothing and equipment. Clothing must be sturdy but allow complete freedom of movement.

• Wear close-fitting clothes such as a boiler suit, not a loose jacket.
• Do not wear clothing which could become trapped in wood, brush, or moving parts of the machine. Do not wear a scarf, necktie, or jewelry. Tie up and confine long hair above your shoulders.
• Wear sturdy shoes with non-slip soles.

WARNING: To reduce the risk of eye injuries, wear close-fitting safety glasses in accordance with European Standard EN 166. Make sure the safety glasses are a snug fit.

Wear face protection and make sure it is a good fit. Face protection alone is not sufficient to protect the eyes.

Wear "personal" sound protection, e.g., ear defenders.

Wear sturdy protective gloves made of a resistant material (e.g., leather).

STIHL can supply a comprehensive range of personal protective equipment.

2.2 Transporting the machine

Always stop the engine.

Carry the unit properly balanced by the shaft or loop handle.

By vehicle: When transporting in a vehicle, properly secure your machine to prevent turnover, damage, and fuel spillage.

2.3 Refueling

WARNING: 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.

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

Only refuel the machine in a well-ventilated place. If fuel has been spilled, immediately clean the machine – do not allow your clothes to be splashed with fuel. If that happens, change your clothes at once.

After refueling, close the fuel cap as tightly as possible.

This helps reduce the risk of unit vibrations causing an incorrectly tightened fuel cap to loosen or come off and spill quantities of fuel.

Check for leaks. Do not start the engine if there is a fuel leak – serious or fatal burns could result!

2.4 Before starting

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

Check the fuel system for leaks, especially the visible parts, e.g., fuel cap, hose connections, manual fuel pump (only in machines with a manual fuel pump). In case of leakage and damage, do not start the engine – risk of fire!

Have the machine serviced by a dealer before using it.

Use only an approved combination of cutting attachment, deflector, handle, and harness. All parts must be assembled properly and securely. To reduce the risk of injury, never use metal cutting attachments!

• Slide control / stop switch must move easily to STOP or 0
• Throttle trigger lockout (if installed) and throttle trigger must move easily – the throttle trigger must return to the idle position automatically
• Check that the spark plug boot is secure – a loose boot may cause sparking that could ignite combustible fumes and cause a fire!
• Check cutting attachment for correct and secure assembly and good condition
• Check safety devices (e.g., deflector for cutting attachments) for damage and/or wear. Always replace damaged parts. Never operate the unit with a damaged deflector
• Never attempt to modify the controls or safety devices
• Keep the handles dry and clean – free from oil and dirt - this is important for safe control of the machine
• Adjust the harness and handle(s) to suit your height and reach

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

To prepare for emergencies when using a harness: Practice setting down the machine quickly. To avoid damage, do not throw the machine to the ground when practicing.

2.5 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 cutting attachment must be clear of the ground and all other obstructions because it may begin to run when the engine starts.

Your power tool is a one-person unit. To reduce the risk of injury from ejected objects, do not allow other persons within a radius of 15 meters of your own position – even when starting.

Avoid contact with the cutting attachment – risk of injury!

Do not drop-start the engine – start it as described in the User Manual.

The cutting attachment runs on for a short while after releasing the throttle trigger - coasting effect!

Check engine idling: The cutting attachment must remain at a standstill when the engine idles – throttle trigger released.

WARNING: 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).

2.6 Holding and guiding the machine

Always hold the unit firmly with both hands on the handles.

Make sure you always have good balance and secure footing.

Left hand on the loop handle, right hand on the shaft handle, even if you are left-handed.

2.7 While working

In the event of impending danger or in an emergency, switch off the engine immediately - move the slide control/stop switch to STOP or 0.

Therefore, do not allow any other persons within a radius of 15 meters of your own position. This distance must also be maintained in relation to objects (vehicles, window panes) – risk of property damage! Even at a distance over 15 m, danger cannot be ruled out.

Check that the engine is properly idling so that the cutting tool will not continue rotating after you release the throttle trigger.

Check and correct the idle speed setting at regular intervals. If the cutting attachment still rotates at idle speed, have your dealer make proper adjustments or repairs.

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

Watch out for obstacles: tree stumps, roots – risk of tripping or stumbling!

Make sure you always have good balance and secure footing.

Only work while standing on the ground, never on a ladder or mobile elevated work platform.

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

Take breaks when you start getting tired or feeling fatigue - risk of accidents!

Work calmly and carefully – in daylight conditions and only when visibility is good. Proceed with caution, do not put others in danger.

As soon as the engine is running, the power machine generates toxic exhaust gas. These gases may be odorless and invisible and may contain unburned hydrocarbons and benzene. 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. This reduces the risk of serious or fatal injury from breathing toxic fumes.

Stop work immediately if you start suffering from nausea, headaches, impaired vision (e.g., your field of vision gets smaller), impaired hearing, dizziness, or impaired concentration – these symptoms may possibly be the result of too-high exhaust gas concentration – Risk of accidents!

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.

WARNING: To reduce the risk of fire, do not smoke while operating or standing near your power tool. Combustible fuel vapor may escape from the fuel system.

Dusts, mist, and fumes emissions during work may be hazardous to your health. Wear respiratory protection in case of heavy dust or smoke emission.

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".

Check in particular that the fuel system has no leaks and the safety equipment is fully operative. Never use a power tool that is no longer safe to operate. In case of doubt, contact a dealer.

Do not operate your power tool in the starting throttle position – engine speed cannot be controlled in this position.

WARNING: Never work without protection suitable for the respective machine and cutting tool - risk of injury by ejected objects!

Check the work site - rocks, metal objects, etc., may be caught up and ejected - possibly over a distance of 15 m - risk of injury! They can also damage the cutting attachment and other property (e.g., parking vehicles, windows).

Be particularly careful when working on difficult, densely grown terrain.

When mowing in high shrubbery, under shrubbery and hedges: Hold the cutting tool at a working height of at least 15 cm – avoid risks to animals.

Before you leave the machine: Shut the engine off.

Check the cutting tool regularly at short intervals, and immediately if you feel a change in its behavior:

• Turn off the engine, hold the device securely, press the cutting attachment against the ground to stop it
• Check the condition and firm seat, watch out for fine cracks

Immediately replace defective cutting tools, also in case of minor hairline cracks.

Clean grass and plant residue off the cutting attachment mounting at regular intervals – remove any build-up of material from the cutting attachment and deflector.

WARNING: To reduce the risk of injury, shut off the engine before replacing the cutting attachment!

Do not continue using or attempt to repair damaged or cracked cutting attachments by welding, straightening, or modifying the shape (out of balance).

Particles or pieces may come off and hit the operator or a bystander at a high speed – risk of most severe injuries!

If a rotating cutting attachment touches a rock or another hard object, sparks may be generated which may possibly ignite combustible materials. Also, dried-out plants and brushwood are combustible, above all in hot and dry weather. If there is a risk of fire, do not use cutting attachments in the vicinity of combustible materials, dried-out plants, or brushwood. It is mandatory that you ask the responsible forestry office about the current fire hazard.

2.7.1 When using mowing heads

Only use the protection with properly mounted blade to ensure that the mowing line is restricted to the permissible length.

WARNING: Always switch off the engine to adjust the mowing line for manually adjustable mowing heads – risk of injury!

Misuse with mowing lines that are too long reduces the working speed of the engine. The constant slipping of the clutch causes overheating and damage to important components (e.g., clutch, plastic housing parts) – e.g., due to the cutting attachment rotating during idling – risk of injury!

2.8 Vibrations

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

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

The period of usage is prolonged by:

• Hand protection (wearing warm gloves)
• Work breaks

The period of usage is shortened by:

• Any personal tendency to suffer from poor circulation (symptoms: frequently cold fingers, tingling sensations).
• Low outside temperatures.
• The force with which the handles are held (a tight grip restricts circulation).

Continual and regular users should monitor closely the condition of their hands and fingers. If any of the above symptoms appear (e.g., tingling sensation in fingers), seek medical advice.

2.9 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 original STIHL replacement parts. They are specifically designed to match your model and meet your performance requirements.

WARNING: 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.

WARNING: 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.

WARNING: 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.

2.10 Cutting Attachments and Deflectors

For safety reasons, only the combinations of cutting attachment, deflector, handle, and shoulder strap approved in the model-specific instruction manual may be used.

Only mowing heads may be used on trimmers with a curved drive tube and loop handle.

2.10.1 Symbols on Deflectors

An arrow shows the direction of rotation of the cutting attachments.

2.11 Mowing Head with Nylon Lines

Nylon line achieves a soft cut for edging and trimming around fence posts, trees, etc. – less risk of damaging tree bark.

WARNING: To reduce the risk of injury, never use steel wire in place of the nylon cutting line.

2.12 STIHL PolyCut 6-3 Mowing Head with Polymer Blades

For mowing unobstructed edges of meadows (without posts, fences, trees, or similar obstacles).

It is important to follow the maintenance instructions for the PolyCut mowing head.

Check the wear limit marks!

Wear limit marks are integrated in the base of the PolyCut.

Do not continue using the PolyCut 6-3 if one of the circular holes (1; arrow) becomes visible or if the projecting rim (2; arrow) has worn away. Install a new mowing head.

WARNING: If the wear limit marks are ignored, there is a risk of the cutting tool shattering and flying parts injuring the operator or bystanders.

To reduce the risk of accidents from shattered blades, avoid contact with stones, metal, and similar solid objects.

Check PolyCut blades for cracks at regular intervals. If a crack is found in one of the blades, always replace all the blades.

3 Approved Combinations of Cutting Attachment, Deflector, Handle and Harness

3.1 Permissible combinations

Choose the correct combination from the table depending on the cutting tool!

WARNING: For safety reasons, no other combinations are permitted – risk of accidents!

3.2 Cutting attachments

3.2.1 Mowing heads

1. STIHL AutoCut C 6-2
2. STIHL DuroCut 5-2
3. STIHL PolyCut 7-3
4. STIHL PolyCut 6-2

3.3 Deflector

1. Guard with blade for mowing heads

3.4 Handle

1. Loop handle

3.5 Carrying strap

1. Shoulder strap can be used

4 Mounting the Loop Handle

The loop handle comes in two different versions.

4.1 Version A

Use the combination wrench to loosen the screw (1).

Fit the loop handle (1) on the drive tube at distance (A) of about 20 cm (8 in.) from the control handle (2).

• Slide the spacer (3) – if supplied – into the loop handle as far as stop.
• Insert the screw (4) through the loop handle and the spacer until the screw head locates in the loop handle's hexagon recess.
• Fit the washer (5).
• Screw on the star knob (6) and tighten it down firmly.

Adjusting loop handle to most comfortable position:

• Loosen the star knob (6).
• Move the loop handle (1) along the drive tube as required.
• Tighten down the star knob (6) firmly.

4.2 Version B

Your new power tool comes with the loop handle mounted on the drive tube, but it must be turned and lined up to suit your requirements.

Line up the loop handle.

Turn the handle to the vertical position.

The loop handle can be adjusted to suit the height and reach of the operator and the application by changing distance (A).

Recommendation: distance (A): about 15 cm (6 in)

5 Mounting the Deflector

Slide the handle to the required position. Tighten down the screw with the combination wrench so that the handle cannot be rotated on the drive tube.

Push the deflector (1) over the clamp (2) as far as stop.

Insert the nut (3) in the hex recess in the deflector – make sure the holes line up.

Insert the screw (4) and tighten it down firmly.

6 Mounting the Cutting Attachment

6.1 Placing power tool on the ground

Switch off the engine.

Lay your trimmer on its back with the loop handle and shroud pointing down and the output shaft facing up.

6.2 Thrust Plate

The thrust plate (1) is shipped with the DuroCut 5-2 and PolyCut 6-3. It is only required for these mowing heads.

• STIHL AutoCut 5-2 mowing head, STIHL AutoCut C 5-2 mowing head: Pull the thrust plate (1), if fitted, off the shaft (2).
• STIHL PolyCut 5-2 mowing head, STIHL FixCut 6-3 mowing head: Slip the thrust plate (1) over the shaft (2) and engage the hex recess (3) on the external hexagon (4).

6.3 Blocking the Shaft

To block the shaft, insert a suitable tool (5) through the holes (6) in the deflector and thrust plate – turn the thrust plate back and forth if necessary.

6.4 Fitting the mowing head with screw mounting

Keep the supplement sheet for the mowing head in a safe place.

Fit the thrust plate.

Screw the mowing head counterclockwise on to the shaft (1) as far as it will go.

Retain the shaft.

Tighten the mowing head.

NOTICE: Remove the tool that was used to block the shaft.

6.5 Removing the Mowing Head

Retain the shaft.

Turn the mowing head counterclockwise.

6.6 Fitting Mowing Head without Screw Mounting

Keep the supplement sheet for the mowing head in a safe place!

6.6.1 STIHL AutoCut C 6-2

Push thrust plate onto the shaft.

Insert the nut (10) into the mowing head.

Turn the mowing head (11) clockwise until it engages the shaft (5).

Retaining the Shaft.

Tighten the mowing head.

WARNING: Nuts that move too easily must be replaced.

NOTICE: Remove the tool that was used to block the shaft.

6.6.2 STIHL PolyCut 6-2, PolyCut 7-3

Place the mowing head (2) on the shaft (3) while inserting the internal hexagon (2) on the hexagon (4).

Hold the mowing head (2) with your hand.

Turn cap (1) clockwise and tighten it firmly by hand.

6.7 Removing the Mowing Head

6.7.1 STIHL AutoCut

Hold the spool housing steady.

Unscrew the cap counterclockwise.

6.7.2 STIHL PolyCut

Retaining the Shaft.

Turn the mowing head counterclockwise.

7 Fuel

The engine requires a mixture of gasoline and engine oil.

WARNING: Avoid direct skin contact with fuel and breathing in of gasoline fumes.

7.1 STIHL MotoMix

STIHL recommends using STIHL MotoMix. This pre-blended fuel is free of benzene and lead, is distinguished by a high octane rating, and always provides the proper mixing ratio.

STIHL MotoMix uses STIHL HP Ultra two-stroke engine oil for optimum engine life.

MotoMix is not available in all markets.

7.2 Mixing fuel

NOTICE: Unsuitable fuels or a mixing ratio that deviates from the specification can lead to severe engine damage. The engine, seals, fuel lines, and fuel tank may be damaged if low-quality gasoline or engine oil is used.

7.2.1 Gasoline

Use only high-quality gasoline with an octane rating of at least 90 ROC – leaded or unleaded.

Gasoline with an alcohol component exceeding 10% can cause impaired engine performance in engines with manually adjustable carburetors and thus should not be used in these engines.

Engines with M-Tronic deliver full engine performance using gasoline with an alcohol component of up to 27% (E27).

7.2.2 Engine oil

If you mix the fuel yourself, use only STIHL two-stroke engine oil or another high-performance engine oil classified as JASO FB, JASO FC, JASO FD, ISO-L-EGB, ISO-L-EGC, or ISO-L-EGD.

STIHL specifies STIHL HP Ultra two-stroke engine oil or an equivalent high-performance engine oil in order to maintain emission limits over the machine's service life.

7.2.3 Mixing ratio

with STIHL two-stroke engine oil 1:50; 1:50 = 1 part oil + 50 parts gasoline

7.2.4 Examples

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

7.3 Storing fuel mixture

Store in approved safety fuel canisters only in a dry, cool, and secure place protected against light and sunlight.

Fuel mixture deteriorates with age – mix only as much as needed for a few weeks. Do not store fuel mixture for longer than 30 days. The fuel mixture can become unusable more quickly if exposed to light, sunlight, or low or high temperatures.

STIHL MotoMix however can be stored for up to 5 years without any problems.

Shake the canister containing the fuel mixture thoroughly before refueling.

WARNING: Pressure may have built up in the canister – open it carefully.

The fuel tank and the canister in which fuel mixture is stored should be cleaned thoroughly from time to time.

Residual fuel and the liquid used for cleaning must be disposed of in accordance with regulations and without harming the environment!

8 Fueling

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

Position the machine so that the filler cap is facing up.

Open the filler 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).

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

9 Starting / Stopping the Engine

9.1 Controls

1 Stop switch

2 Throttle trigger lockout

3 Throttle trigger

4 Tongue of throttle trigger

5 Catch

9.1.1 Positions of stop switch

6 Run I

7 Stop 0

9.2 Starting

Move the stop switch to I.

Press down the throttle trigger lockout and hold it there.

Squeeze the throttle trigger until the catch on the tongue (4) can be engaged on the housing (arrow).

Now release the throttle trigger, tongue, and trigger lockout in that order. This is the starting throttle position.

Put the unit on the ground: It must rest securely on the engine support and the deflector. Check that the cutting attachment is not touching the ground or any other obstacles.

Make sure you have a firm footing.

Hold the unit with your left hand and press it down firmly – your thumb should be under the fan housing.

NOTICE: Do not stand or kneel on the drive tube.

Set the choke lever (8) to ❄️ (if the engine is cold) or ☀️ (for warm start – also use this position if the engine has been running but is still cold).

Press the manual fuel pump bulb (9) at least five times – even if the bulb is filled with fuel.

9.2.1 Cranking

Hold the starter grip with your right hand.

9.2.2 Version without ErgoStart

Pull the starter grip slowly until you feel it engage and then give it a brisk strong pull.

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

9.2.3 Version with ErgoStart

Pull the starter grip slowly until you feel it engage and then pull it out slowly and steadily.

9.2.4 Both versions

NOTICE: Do not pull out the starter rope all the way – 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.

9.2.5 When engine begins to fire

After no more than five pulls, move the choke lever (8) to ☀️ and continue cranking.

9.2.6 As soon as the engine runs

Squeeze the throttle trigger to disengage the tongue - the engine will settle down to idle speed.

WARNING: Make sure the carburetor is correctly adjusted. The cutting attachment must not rotate when the engine is idling.

Your machine is now ready for operation.

9.3 Stopping the engine

Move the stop switch to 0.

9.4 If engine does not start

Choke lever

If you did not move the choke lever quickly enough to ☀️ after the engine began to fire, the engine is flooded.

Set choke to ❄️ and

Move the stop switch to I, interlock lever and throttle trigger to the starting throttle position.

Start the engine by pulling the starter rope briskly - 10 to 20 pulls may be necessary.

If the engine still does not start:

• Move the stop switch to 0.
• Remove the spark plug – see "Spark Plug".
• Dry the spark plug.
• Crank the engine several times with the starter to clear the combustion chamber.
• Refit the spark plug – see "Spark Plug".
• Move the stop switch to ☀️, even if the engine is cold.
• Now start the engine.

9.4.1 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 to suit the engine temper-ature.

Start the engine.

10 Operating Instructions

10.1 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.

10.2 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 engine-mounted components (ignition, carburetor) from thermal overload.

10.3 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-of-service periods – see "Storing the Machine".

11 Cleaning the Air Filter

11.1 If there is a noticeable loss of engine power

Set the choke lever to ❄️.

Press in the tab (1) and swing the filter cover (2) down.

Clean away loose dirt from around the filter.

Remove the felt element (3) from the filter housing (4) and replace it – knock out or blow out as a temporary measure – do not wash.

Replace damaged parts.

Fit the felt element (3) in the filter housing (4).

Close the filter cover so that it snaps into position.

12 Adjusting the Carburetor

12.1 General Information

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

12.2 Preparations

• Shut off the engine.
• Mount the cutting attachment.
• Check the air filter and clean or replace if necessary.
• Check the spark arresting screen in the muffler and clean or replace if necessary. STIHL recommends that you have servicing and repair work carried out exclusively by an authorized STIHL servicing dealer.

12.3 Different Standard Settings

Different carburetors are installed at the factory. A different standard setting is necessary for each of these carburetors.

12.4 Identifying the Carburetor

Use the following illustrations to identify the carburetor installed in your machine and then adjust the carburetor as described:

12.4.1 Carburetor1

Carburetor with limiter caps on high speed screw (H) and low speed screw (L).

12.4.2 Carburetor2

Carburetor without limiter caps on high speed screw (H) and low speed screw (L).

12.5 Standard Setting on Carburetor1

Turn high speed screw (H) counterclockwise as far as stop (no more than 3/4 turn).

Turn the low speed screw (L) carefully clockwise until it is against its seat, then back it off a 3/4 turn.

12.6 Standard Setting on Carburetor2

Turn the low speed screw (L) carefully clockwise until it is against its seat, then turn it back 2 full turns.

Turn the low speed screw (L) carefully clockwise until it is against its seat, then turn it back 1 1/2 turns.

12.7 Adjusting Idle Speed

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

12.7.1 Engine stops while idling

Turn the idle speed screw (LA) slowly clockwise until the engine runs smoothly – the cutting attachment must not rotate.

12.7.2 Cutting attachment rotates when engine is idling

Turn the idle speed screw (LA) counterclockwise until the cutting attachment stops moving and then turn the screw another 1/2 to 1 full turn in the same direction.

WARNING: If the cutting attachment continues to rotate when the engine is idling, have your machine checked and repaired by your servicing dealer.

12.7.3 Erratic idling behavior, poor acceleration (despite correction to setting of LA screw).

Idle setting is too lean

• Carburetor1: Turn the low speed screw (L) carefully counterclockwise, no further than stop, until the engine runs smoothly and still accelerates satisfactorily.
• Carburetor2: Rotate the low speed screw (L) slowly about 1/4 turn counterclockwise until the engine runs smoothly and still accelerates satisfactorily.

12.7.4 Erratic idling behavior

Idle setting is too rich

• Carburetor1: Turn the low speed screw (L) slowly clockwise, no further than stop, until the engine runs smoothly and still accelerates satisfactorily.
• Carburetor2: Rotate the low speed screw (L) slowly about 1/4 turn clockwise until the engine runs smoothly and still accelerates satisfactorily.

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

12.8 Fine Tuning for Operation at High Altitude

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

• Carburetor1: Carry out the standard setting. Warm up the engine. Turn high speed screw (H) slightly clockwise (leaner) – no further than stop.
• Carburetor2: Carry out the standard setting. Warm up the engine. Turn high speed screw (H) slightly clockwise (leaner) – no more than a 3/4 turn.

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.

13 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".

13.1 Removing the Spark Plug

Move the stop switch to 0.

Pull off the spark plug boot (1).

Unscrew the spark plug.

13.2 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.

14 Engine Running Behavior

Dirty air filter.

Unfavorable running conditions.

If engine running behavior is unsatisfactory even though the air filter is clean and the carburetor is properly adjusted, the cause may be the muffler. Have the muffler checked for contamination (carbonization) by your servicing dealer.

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

15 Storing the Machine

If out of use for periods of about 30 days or longer:

• Drain and clean the fuel tank in a well-ventilated area.
• Dispose of fuel properly in accordance with local environmental requirements.
• If a manual fuel pump is fitted: Press the manual fuel pump at least 5 times.
• Start the engine and run it at idling speed until it stops.
• Remove, clean, and inspect the cutting attachment. Coat metal cutting attachments with corrosion inhibitor.
• Thoroughly clean the machine – pay special attention to the cylinder fins and air filter.

Store the machine in a dry and secure location – out of the reach of children and other unauthorized persons.

16 Maintaining the Mowing Head

16.1 Placing power tool on the ground

Switch off the engine.

Lay your trimmer on its back with the loop handle and shroud pointing down and the output shaft facing up.

16.2 Replacing Nylon Line

Always check the mowing head for signs of wear before replacing the nylon line.

WARNING: If there are signs of serious wear, replace the complete mowing head.

The nylon mowing line is referred to as "nylon line" or "line" in the following.

The mowing head is supplied with illustrated instructions for replacing the nylon line. Keep the instructions for the mowing head in a safe place.

If necessary, remove the mowing head.

16.3 Adjusting Nylon Line

16.3.1 STIHL AutoCut

WARNING: To reduce the risk of injury, always shut off the engine before adjusting the nylon mowing line by hand.

Hold the rotating mowing head above the ground – tap it on the ground once about 3 cm (1.2 in) of fresh line is advanced.

The blade (1) on the deflector (2) trims surplus line to the correct length – avoid tapping the mowing head more than once at a time.

Line feed operates only if both lines still have a minimum length of 2.5 cm (1 in).

If the line is shorter than 2.5 cm (1 in):

WARNING: To reduce the risk of injury, always shut off the engine before adjusting the nylon mowing line by hand.

• Turn the machine over.
• Press down the cap on the spool as far as stop.
• Pull the ends of the lines out of the spool.
• If the spool is empty, refill with nylon line.

16.3.2 All other mowing heads

Refer to the leaflet supplied with the mowing head.

16.4 Replacing Nylon Line STIHL DuroCut

WARNING: To reduce the risk of injury, always shut off the engine before refilling the mowing head.

Fit nylon line in the mowing head as described in the instructions supplied.

16.5 Replacing Cutting Blades

16.5.1 STIHL PolyCut

Always check the mowing head for signs of wear before installing new cutting blades.

WARNING: If there are signs of serious wear, replace the complete mowing head.

The thermoplastic cutting blades are referred to as "blades" in the following.

The mowing head is supplied with illustrated instructions for replacing the blades. Keep the instructions for the mowing head in a safe place.

WARNING: To reduce the risk of injury, always shut off the engine before installing the blades.

• Remove the mowing head.
• Replace blades as shown in the illustrated instructions.
• Mount the mowing head on the machine.

17 Inspections and Maintenance by Dealer

17.1 Maintenance work

STIHL recommends that maintenance and repair work be carried out only by authorized STIHL dealers.

17.2 Fuel pickup body in tank

Have the pickup body in the fuel tank replaced every year.

17.3 Spark Arrestor in Muffler and Spacer

WARNING: To reduce the risk of damage to persons or objects from contact with hot parts, never operate the machine without a spacer, or with the spacer damaged.

See "Main Parts" for positions of spark arrestor and spacer.

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

18 Maintenance and Care

The following intervals apply for normal operating conditions. The specified intervals must be shortened accordingly when working for longer than normal or under difficult cutting conditions (extensive dust, etc.).

¹⁾STIHL recommends STIHL dealers

19 Main Parts

The following intervals apply for normal operating conditions. The specified intervals must be shortened accordingly when working for longer than normal or under difficult cutting conditions (extensive dust, etc.).

¹⁾STIHL recommends STIHL dealers

1 Loop handle

2 Spacer

3 Stop switch

4 Throttle trigger lockout

5 Throttle trigger

6 Choke lever

7 Air filter cover

8 Tank cap

9 Tank

10 Machine support

11 Manual fuel pump

12 Carburetor adjusting screws

13 Starter grip

14 Spark plug boot

15 Muffler with spark arrestor

16 Spacer

17 Line limiting blade

18 Deflector

19 Mowing head

20 Drive tube

# Serial number

20 Specifications

20.1 Engine

Single-cylinder two-stroke engine

Displacement: 27.2 cm³

Cylinder bore: 34 mm

Piston stroke: 30 mm

Engine power to ISO 8893: 0.75 kW (1 hp) at 8300 1/min

Idle speed: 2800 rpm

20.6 REACH

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

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

20.7 Exhaust Emissions

The CO2 value measured in the EU type approval procedure is specified at www.stihl.com/co2 in the product-specific technical data.

The measured CO2 value was determined on a representative engine in accordance with a standardized test procedure under laboratory conditions and does not represent either an explicit or implied guarantee of the performance of a specific engine.

The applicable exhaust emission requirements are fulfilled by the intended usage and maintenance described in this User Manual. The operating license shall be void if the engine is modified in any way.

21 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 high-quality 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 STIHL logo and the STIHL parts symbol ⚙️ (the symbol may appear alone on small parts).

22 Disposal

Contact the local authorities or your STIHL servicing dealer for information on disposal.

Improper disposal can be harmful to health and pollute the environment.

Take STIHL products including packaging to a suitable collection point for recycling in accordance with local regulations.

Do not dispose with domestic waste.

23 EC Declaration of Conformity

ANDREAS STIHL AG & Co. KG

Badstr. 115

D-71336 Waiblingen

Germany

declare under our sole responsibility that:

Designation: Brushcutter

Make: STIHL

FS 45

FS 45 C

FS 45 C-E

Series:

Serial identification number: 4140

Displacement: 27.2 cm³

conforms to the relevant provisions of Directives 2011/65/EU, 2006/42/EC, 2014/30/EU and 2000/14/EC and has been developed and manufactured in compliance with the following standards in the versions valid on the date of production:

EN ISO 11806-1, EN 55012, EN 61000-6-1

The measured and the guaranteed sound power level have been determined in accordance with Directive 2000/14/EC, Annex V, and standard ISO 10884.

Measured sound power level 109 dB(A)

Guaranteed sound power level 111 dB(A)

Technical documents deposited at: ANDREAS STIHL AG & Co. KG Produktzulassung

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

Done at Waiblingen, 03.02.2020

ANDREAS STIHL AG & Co. KG

pp

J. Hoffman

Dr. Jürgen Hoffmann

Director Product Certification & Regulatory Affairs

CE