541RB - Brush cutter HUSQVARNA - Free user manual and instructions

Product Type	Brushcutter (backpack unit with interchangeable cutting attachments)
Engine Type	Two-stroke, air-cooled
Cylinder Displacement	41.5 cm³
Maximum Engine Output	1.47 kW @ 7000-7500 rpm (ISO 8893)
Maximum Speed	12000 rpm
Idle Speed	2500 ± 200 rpm
Fuel Tank Capacity	1.3 L
Fuel Mixture	Gasoline (min. 90 RON, max 10% ethanol) + 2-stroke oil (50:1 ratio)
Spark Plug	Champion RCJ-6Y
Electrode Gap	0.6-0.7 mm
Weight (without fuel, cutting attachment, guard)	9.0 kg
Sound Pressure Level (at operator's ear)	87 dB(A) (EN ISO 11806)
Vibration Level (grass blade, grip/handle)	10 m/s² (EN ISO 11806)
Cutting Attachments	Grass blade (Multi 300-3 or Grass 255-4), Trimmer head PT104
Cutting Attachment Guard	Included (art. no. 577 32 97-01)
Harness	Included (shoulder harness)
Handle	Loop handle
Stop Switch	Yes
Throttle Trigger Lockout	Yes
Vibration Damping System	Yes
Cooling System	Air-cooled (cylinder fins and air intake)
Bevel Gear Grease	Fill to 3/4 with Husqvarna special grease
Drive Shaft Lubrication	Periodically (every 100 hours)
Maintenance Schedule	Daily, weekly, monthly checks as per manual

Frequently Asked Questions - 541RB HUSQVARNA

What fuel mixture should I use for the Husqvarna 541RB?

Use a mixture of unleaded gasoline (minimum 90 RON, max 10% ethanol) and high-quality 2-stroke oil in a 50:1 ratio (2% oil). Husqvarna alkylate fuel is recommended for best performance.

How do I start the engine?

Turn the fuel lever to vertical, push the choke lever up, set throttle to idle, place the product on flat ground, hold the shaft with left hand and put right foot on frame, then pull the starter rope quickly. Once started, push choke down gradually.

How do I adjust the idle speed?

Warm up the engine, then turn the idle adjustment screw clockwise until the cutting attachment starts to rotate, then turn counterclockwise until it stops. The correct idle speed is 2500 ± 200 rpm.

What type of spark plug does the 541RB use?

It uses a Champion RCJ-6Y spark plug with an electrode gap of 0.6-0.7 mm. Always use the recommended type to avoid engine damage.

How often should I clean the air filter?

Clean the air filter every 25 hours of operation. Use compressed air or wash with warm water and soap. If damaged, replace it. After cleaning, apply Husqvarna special air-filter oil.

What cutting attachments are approved for this brushcutter?

Approved attachments include grass blade Multi 300-3 (Ø 300 mm, 3 teeth), grass blade Grass 255-4 (Ø 255 mm, 4 teeth), and trimmer head PT104 (M10 x 1.25 L). Always use the corresponding cutting attachment guard.

How do I adjust the throttle cable play?

Stop the product, push throttle lever to lowest speed, loosen locknut, and turn cable adjuster until play is 1-2 mm. Turn clockwise to increase play, counterclockwise to decrease. Retighten locknut.

What is the minimum safety distance during operation?

Keep a minimum distance of 15 meters (50 feet) to persons and animals during operation. Always look behind before turning and stop immediately if someone enters the safety zone.

How should I transport and store the brushcutter?

Let the product cool before transport or storage. Remove spark plug cap for long-term storage. Attach the transport guard, secure the product to prevent movement, and ensure no fuel leaks or sparks. Empty fuel tank for long-term storage.

How do I replace the trimmer line?

Refer to the manual for the specific trimmer head. Generally, remove the spool, wind the line tightly and evenly, and ensure the line can be cut by the knife on the guard. Soak the line in water for 2 days before use to increase lifespan.

USER MANUAL 541RB HUSQVARNA

Silhouette of a vacuum cleaner with a tripod-mounted device (no text or symbols)

531RB, 541RB

EN Operator's manual 11-26

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Contents

Introduction.... 11

Safety....12

Assembly.... 16

Operation.... 17

Maintenance.... 20

Troubleshooting.... 24

Transportation and storage....24

Technical data.... 25

Accessories.... 26

Appendix 61

Introduction

Product overview

(Fig. 1)

1. Bevel gear
2. Grease filler cap, bevel gear
3. Cutting attachment guard

4. Shaft

5. Loop handle

6. Throttle trigger

7. Stop switch

8. Flexible drive shaft coupling

9. Starter rope handle

10. Fuel tank

11. Muffler cover

12. Cylinder cover

13. Spark plug cap and spark plug

14. Choke control

15. Frame

16. Flexible drive shaft

17. Locknut

18. Support cup

19. Holder A

20. Holder B

21. Screw

22. Cover

23. Transport guard

24. 2T blade

25. Trimmer head

26. Combination wrench

27. Hex key

28. Operator's manual

29. Socket wrench

30. Harness

Product description

The product is a backpack unit with interchangeable cutting attachments.

Intended use

Use the product with a grass blade or a trimmer head to cut different types of vegetation. Do not use the product for other tasks than grass trimming and grass clearing.

Note: National or local regulations can regulate the use. Comply to given regulations.

Only use the product with accessories that are approved by the manufacturer. See Accessories on page 26.

Symbols on the product

(Fig. 2)
WARNING! This product is dangerous. Injury or death can occur to the operator or bystanders if the product is not used carefully and correctly. To prevent injury to the operator or bystanders, read and obey all safety instructions in the operator's manual.
(Fig. 3)
Read the operator's manual carefully and make sure that you understand the instructions before use.
(Fig. 4)
Use a protective helmet in locations where objects can fall on you. Use approved hearing protection and approved eye protection.
(Fig. 5)
Use approved protective gloves.
(Fig. 6)
Use heavy-duty slip-resistant boots.
(Fig. 7)
The product can cause objects to eject, which can cause injury.
(Fig. 8)
Maximum speed of the output shaft.
(Fig. 9)
Keep a minimum distance of 15 m / 50 ft.. to persons and animals during operation of the product.

(Fig. 10) Risk of blade thrust if the cutting equipment touches an object that it does not immediately cut. The product can cut off body parts. Keep a minimum of 15 m / 50 ft. distance to persons and animals during operation of the product.

(Fig. 11) Only use a flexible cutting wire. Do not use metal cutting elements. Apply this for grass guard accessory.

(Fig. 12) The arrows show the limit for the handle position.

(Fig. 13) Choke.

(Fig. 14) Fuel lever.

The rating plate shows the serial number. yyyy is the production year and ww is the production week.

Note: Other symbols/decals on the product refer to certification requirements for other commercial areas.

Product liability

As referred to in the product liability laws, we are not liable for damages that our product causes if:

• the product is incorrectly repaired.
- the product is repaired with parts that are not from the manufacturer or not approved by the manufacturer.
- the product has an accessory that is not from the manufacturer or not approved by the manufacturer.
- the product is not repaired at an approved service center or by an approved authority.

Safety

Safety definitions

Warnings, cautions and notes are used to point out specially important parts of the manual.

WARNING: Used if there is a risk of injury or death for the operator or bystanders if the instructions in the manual are not obeyed.

CAUTION: Used if there is a risk of damage to the product, other materials or the adjacent area if the instructions in the manual are not obeyed.

Note: Used to give more information that is necessary in a given situation.

General safety instructions

WARNING: Read the warning instructions that follow before you use the product.

• This product produces an electromagnetic field during operation. This field may under some circumstances interfere with active or passive medical implants. To reduce the risk of serious or fatal injury we recommend persons with medical implants to consult their physician and the medical implant manufacturer before operating this product.

• Do not use the product if you are tired, ill, or under the influence of alcohol, drugs or medicine. This has a negative effect on your vision, alertness, coordination and judgment.

• Do not operate the product in bad weather, such as dense fog, heavy rain, strong wind and intense cold. To operate the product in bad weather can make you tired and add risks, such as icy ground and unpredictable felling direction.
• Always be careful and use your common sense. If you feel uncertain about a work situation or the operating procedures after you read the operator's manual, speak to a servicing dealer before you continue.
• Remove the spark plug cap if you let the product out of view.

Safety instructions for assembly

WARNING: Read the warning instructions that follow before you use the product.

• Use approved protective gloves when you assemble the product and cutting attachment.
• Remove the spark plug cap from the spark plug before you assemble the product.
• Make sure that the correct handlebar and cutting attachment guard are assembled before you operate the product.

• A defective or incorrect cutting attachment guard can cause injury. Do not use a cutting attachment without an approved cutting attachment guard.

• Attach the clutch cover and shaft correctly before you start the product.

• The drive disc and support flange must engage correctly in the center hole of the cutting attachment. A cutting attachment that is attached incorrectly can cause injury or death.
• Attach the harness to the product to prevent injury to the operator or others.

Safety instructions for operation

WARNING: Read the warning instructions that follow before you use the product.

• Learn and understand the difference between forestry clearing, grass clearing and grass trimming before you use the product.
• Use personal protective equipment, see Personal protective equipment on page 13
• Long-term exposure to noise can result in permanent hearing loss. Always use approved hearing protection.
• Listen for warning signals and loud voices when you use hearing protection. Always remove your hearing protection when the engine stops.
• Never use the product if it is changed or defective.
• Make sure that the spark plug cap and ignition lead are not damaged to prevent the risk of electrical shock.
• Look around the work area to make sure that no persons, animals or objects have a negative effect on the safety of the operation of the product.
• Look around the work area to make sure that no persons or animals touch the cutting attachment or are hit by objects that are ejected from the cutting attachment.
• Examine the work area. Remove all loose objects, such as stones, broken glass, nails, steel wire and string, that can eject or wind around the cutting attachment.
• Do not use the product in a situation or location where you can not get aid if an accident occurs.
• Do not use the product without a guard.
• Make sure that persons or animals keep a distance of a minimum of 15 m during work. Always look behind you before you turn around with the product. Stop the product immediately if a person or animal enters the 15 m safety zone. If more than one operator does work in the same area, keep a safety distance of a minimum of 2 times the tree height and a minimum of 15 m.
• Make sure that you can move safely and have a safe stance. Examine the area around you for obstacles such as roots, rocks, branch and ditches. Be careful during work on slopes.

• Do not overreach. Keep a stable position of the feet and a good balance at all times.

• Before you start the product, put it on a flat surface, at a minimum of 3 m from the fuel source and from where you fill fuel. Make sure that there are no objects near or touching the cutting attachment.

• If the cutting attachment rotates at idle speed, let a service agent adjust it. Do not use the product until it is adjusted or repaired.
• Look out for thrown objects. Always use approved eye protection and keep away from the cutting attachment guard. Stones and other small objects can eject into your eyes and cause blindness or other injuries.
• Do not put the product down with the engine on unless you have it in clear view.
• Do not remove the cut material, or let other persons remove cut material, while the engine is on or the cutting equipment rotates, as this can result in serious injury.
  • Always stop the engine and make sure that the cutting equipment does not rotate before you remove material that is wound around the blade shaft or caught between the guard and the cutting attachment.
• Be careful when you remove material from around the cutting equipment. The bevel gear gets hot during operation and can cause burn injuries.
• The exhaust fumes from the engine are hot and can contain sparks. Risk of fire. Be careful around dry and flammable material.
• Stop the engine before you move to a new work area. Always attach the transport guard before you move the equipment.
  • Overexposure to vibration can lead to circulatory damage or nerve damage in persons who have poor circulation. Speak to your physician if you experience symptoms of overexposure to vibration. Such symptoms include numbness, loss of feeling, tingling, pricking, pain, loss of strength, changes in skin color or condition. These symptoms usually show in the fingers, hands or wrists. The risk increases at low temperatures.

Personal protective equipment

WARNING: Read the warning instructions that follow before you use the product.

• Always use approved personal protective equipment when you use the product. Personal protective equipment cannot fully prevent injury but it decreases the degree of injury if an accident does occur. Let your dealer help you select the correct equipment.
- Use a helmet if the trees in the work area have a height of more than 2 m/6.5 ft.

(Fig. 15)

- Use approved hearing protection.

(Fig. 16)

- Use approved eye protection. If you use a visor, you must also use approved protective goggles. Approved protective goggles must comply with the ANSI Z87.1 standard in the USA or EN 166 in EU countries.

(Fig. 17)

• Use gloves when it is necessary, for example when you attach, examine or clean the cutting equipment. (Fig. 18)
• Use protective boots with steel toe-cap and non-slip soles.

(Fig. 19)

• Use clothing made of a strong fabric. Always use heavy, long pants and long sleeves. Do not use loose clothing that can catch on twigs and branches. Do not use jewelry, short pants or sandals. Do not go with bare feet. Put your hair up safely above shoulder level.
• Keep first aid equipment near.

(Fig. 20)

Safety devices on the product

For information about where to find the safety devices, see Product overview on page 11.

WARNING: Read the warning instructions that follow before you use the product.

• Do not use a product with defective safety devices. Do a check of and do maintenance on the safety devices regularly. If the safety devices are defective, speak to your Husqvarna service agent.
• Do not make changes to safety devices. Do not use the product if protective covers, safety switches or other protective devices are not attached or are defective.
• For all service and repair work on the product, especially for the safety devices, special training is necessary. If the safety devices fail the checks given in this operator's manual, you must let a service agent help you. We guarantee that professional repairs and service is available. If your dealer is not a service agent, speak to them for information about the nearest service agent.
• Do not use a cutting attachment without an approved and correctly attached cutting attachment guard. See To assemble the cutting equipment on page 16.

To do a check of the throttle trigger lockout

The throttle trigger lockout locks the throttle trigger at the idle position.

1. Start the engine and apply full throttle.

2. Release the throttle trigger and make sure that the cutting attachment stops. If the cutting attachment rotates, then the carburetor idle speed must be adjusted. Refer to To adjust the idle speed on page 22. (Fig. 21)

To do a check of the stop switch

1. Start the engine.
2. Move the stop switch to the stop position and make sure that the engine stops. (Fig. 22)

To do a check of the stop switch

1. Start the engine.
2. Move the stop switch to the stop position and make sure that the engine stops. (Fig. 23)

To do a check of the cutting attachment guard

The cutting attachment guard stops objects that ejects in the direction of the operator. It also prevents injuries that occur if you touch the cutting attachment.

1. Stop the engine.
2. Do a visual check for damages, for example cracks. (Fig. 24)
3. Replace the cutting attachment guard if it is damaged.

To do a check of the vibration damping system

The vibration damping system decreases vibration in the handles to a minimum which makes the operation easier.

1. Stop the engine.
2. Do a visual check for deformation and damage, for example cracks.
3. Make sure that the elements of the vibration damping system are attached correctly. (Fig. 25)

To do a check of the muffler

WARNING: Never use a product with a faulty muffler.

(Fig. 26)

WARNING: Bear in mind that the exhaust fumes from the engine are hot and may contain sparks which can start a fire. Never start the product indoors or near combustible material!

The muffler keeps noise levels to a minimum and sends exhaust fumes away from the operator. For mufflers it is very important that you follow the instructions on how to check, maintain and service your product.

(Fig. 27)

- Regularly check that the muffler is securely attached to the product. (Fig. 28)

Cutting attachment

WARNING: Read the warning instructions that follow before you use the product.

- Do the regular maintenance. Let an approved service center regularly examine the cutting attachment to do adjustments or repairs.

- The performance of the cutting attachment increases.

- The life of the cutting attachment increases.

• The risk of accidents decreases.

- Only use an approved cutting attachment guard. Refer to Accessories on page 26.

- Do not use a damaged cutting attachment.

Grass trimmer head

• Make sure that you wind the grass trimmer line tightly and equally around the drum to decrease the vibration.
• Use only the approved grass trimmer heads and grass trimmer lines. Refer to Accessories on page 26
• Use a correct length of the grass trimmer line. A long grass trimmer line uses more engine power than a short grass trimmer line.
• Make sure that the cutter on the cutting attachment guard is not damaged.
• Soak the grass trimmer line in water for 2 days before you attach the grass trimmer line to the product. This increases the life of the grass trimmer line.
• Refer to the instructions for the cutting attachment to use the correct procedure to load the cord and the correct cord diameter.

Grass blade

- Use correctly sharpened blades. An incorrectly sharpened or damaged blade increases the risk of injury. Refer to the instructions on the blade packaging.

- Use correctly set blades. An incorrectly set blade increases the risk of injury and damage.

Fuel safety

WARNING: Read the warning instructions that follow before you use the product.

• Do not mix the fuel indoor or near a heat source.
• Do not start the product if there is fuel or engine oil on the product. Remove the unwanted fuel/oil and let

the product dry. Remove unwanted fuel from the product.

• If you spill fuel on your clothing, change clothing immediately.
• Do not get fuel on your body, it can cause injury. If you get fuel on your body, use a soap and water to remove the fuel.
• Do not start the engine if you spill oil or fuel on the product or on your body.
• Do not start the product if the engine has a leak. Examine the engine for leaks regularly.
• Be careful with fuel. Fuel is flammable and the fumes are explosive and can cause injuries or death.
• Do not breathe in the fuel fumes, it can cause injury. Make sure that there is sufficient airflow.
• Do not smoke near the fuel or the engine.
• Do not put warm objects near the fuel or the engine.
• Do not add the fuel when the engine is on.
• Make sure that the engine is cool before you refuel.
• Before you refuel, open the fuel tank cap slowly and release the pressure carefully.
• Make sure there are sufficient airflow when refueling and mixing fuel (petrol and two-stroke oil) or draining the fuel tank.
• Fuel and fuel vapor are highly flammable and can cause serious injury when inhaled or allowed to come into contact with the skin. For this reason, observe caution when handling fuel and make sure there is sufficient airflow.
• Tighten the fuel tank cap carefully or a fire can occur.
• Move the product at a minimum of 3 m (10 ft) from the position where you filled the tank before a start.
• Do not put too much fuel in the fuel tank.
• Make sure that a leak cannot occur when you move the product or fuel container.
• Do not put the product or a fuel container where there is an open flame, spark or pilot light. Make sure that the storage area does not contain an open flame.
• Only use approved containers when you move the fuel or put the fuel into storage.
• Empty the fuel tank before long-term storage. Obey the local law on where to dispose fuel.
• Clean the product before long-term storage.
• Remove the spark plug cap before you put the product into storage to make sure that the engine does not start accidentally.

Safety instructions for maintenance

WARNING: Read the warning instructions that follow before you use the product.

- Stop the engine, make sure that the cutting attachment stops. Remove the cylinder cover and

disconnect the spark plug cap before you do the maintenance.

• The exhaust fumes from the engine contain carbon monoxide, an odourless, poisonous and very dangerous gas that can cause death. Do not run the product indoors or in closed spaces.
• The exhaust fumes from the engine are hot and can contain sparks. Do not run the product indoors or near flammable material.
• Accessories and changes to the product that are not approved by the manufacturer, can cause serious

injury or death. Do not change the product. Always use original accessories.

• If the maintenance is not done correctly and regularly, there is an increased risk of injury and damage to the product.
• Only do the maintenance as this operator's manual recommends. Let an approved Husqvarna service agent do all other servicing.
• Let an approved Husqvarna service agent do servicing on the product regularly.
• Replace damaged, worn or broken parts.

Assembly

Introduction

WARNING: Before you assemble the product, you must read and understand the safety chapter.

WARNING: Remove the spark plug cable from the spark plug before you assemble the product.

To assemble the cutting equipment

The cutting equipment includes a cutting attachment and a cutting attachment guard.

WARNING: Use protective gloves.

WARNING: Always use the cutting attachment guard that is recommended for the cutting attachment. See Accessories on page 26.

WARNING: An incorrectly attached cutting attachment can result in injury or death.

To assemble the flexible drive shaft

1. Remove the screw at the shaft coupling. (Fig. 29)
2. Put the flexible drive shaft through the loops at the wire harness.
3. Turn and push the flexible drive shaft at the same time to connect it.
4. Tighten the 2 screws.
5. Assemble the drive shaft sleeve in the clutch cover. Turn and push the drive shaft at the same time to connect it. (Fig. 30)
6. Make sure that the locking pin goes back to its initial position.

To connect the throttle cable and the stop switch wires

1. Open the cover.
2. Connect the throttle wire from the wire harness (A) and the throttle wire (B) from the engine in the cover. (Fig. 31)
3. Close the cover.
4. Connect the stop switch wires into the related connectors from the engine. (Fig. 32)

Note: Wire polarity is not important.

1. Attach the stop switch wires with the clamp.

To examine the play of the throttle cable

1. Stop the product.
2. Pull the throttle cable lightly to examine the play of the throttle cable.
3. Make sure that the play is 1-2 mm.
4. If the play is less than 1 mm or more than 2 mm, refer to To adjust the play of the throttle cable on page 21.

To attach the loop handle

1. Put the loop handle on the shaft. (Fig. 33) (Fig. 34)
2. Attach the loop handle with the nut and the screw. Do not tighten fully.
3. Adjust the position of the handle to an applicable work position and tighten the screws fully.

To assemble the loop handle

1. Put the loop handle on the shaft.
2. Attach the spacer into the slot in the loop handle. Attach the nut and the screw. Do not tighten fully. (Fig. 35)
3. Adjust the product to an applicable work position.
4. Tighten the nut and the screw.

To attach the cutting attachment guard

1. Put the cutting attachment guard on the shaft.

2. Attach the cutting attachment guard with 2 screws.

a) If the blade guard is used, make sure it is attached as shown in the illustration. (Fig. 36)
b) If the trimmer guard is used, make sure that it is attached between the arrows. (Fig. 37)

To attach the trimmer head

Note: Turn the trimmer head counterclockwise when installing.

1. Align the hole on the cover and the groove on the gearbox.
2. Attach the cover with the screw/screws. (Fig. 38)
3. Put the holder (B) on the output shaft.
4. Turn the output shaft to align one of the holes in the holder (B) with the related hole in the gear housing.
5. Put the locking pin in the hole to lock the shaft.

CAUTION: Make sure that the trimmer line can be cut by the knife on the trimmer guard.

To attach the grass blade or the grass cutter

1. Align the hole on the cover and the groove on the gearbox.
2. Attach the cover with the screw/screws. (Fig. 39)

3. Put the blade between holder (A) and holder (B).

4. Turn the output shaft to align one of the holes in the holder (A) with the related hole in the gear housing.

5. Put the locking pin in the hole to lock the shaft.
6. Make sure that the drive disc and the support flange engages correctly in the center hole of the blade. (Fig. 40)
7. Tighten the nut with the socket wrench. Hold the shaft of the socket wrench near the blade guard. Tighten in the opposite direction to how the cutting attachment rotates. Tighten it to a torque of 15-20 Nm.

To install the 2-teeth blade in the guard

1. Install the blade in the transport guard. (Fig. 41)

To assemble the shoulder harness

1. Put the ring of the shoulder harness strap through the hook (A) and attach it with the bolt.
2. Attach the hook (B) of the shoulder strap to the ring (C) on the frame. (Fig. 42)

To adjust the shoulder harness

1. Stop the engine.
2. Put on the harness.
3. Adjust the shoulder strap to make the product weigh equally on your shoulders.

Operation

Introduction

WARNING: Before you operate the product, you must read and understand the safety chapter.

Before you operate the product

• Examine the work area to make sure that you know the type of terrain, the slope of the ground and if there are obstacles such as stones, branches and ditches.
• Do an overhaul inspection of the product.
• Do the safety inspections, maintenance and servicing that are given in this manual.
• Make sure that all covers, guards, handles and the cutting equipment are correctly attached and not damaged.
• Make sure that there are no cracks at the bottom of the grass blade teeth or by the center hole of the blade. Replace the blade if it is damaged.

(Fig. 43)

• Examine the support flange for cracks. Replace the support flange if it is damaged.
  (Fig. 44)
• Make sure that the locknut can not be removed by hand. If you can remove it by hand, it does not lock the cutting attachment sufficiently and you must replace it.
  (Fig. 45)
• Examine the blade guard for damages or cracks. Replace the blade guard if it has been hit or if it has cracks.
  (Fig. 46)
• Examine the trimmer head and cutting attachment guard for damages or cracks. Replace the trimmer head and cutting attachment guard if they have been hit or if they have cracks.
  (Fig. 47)

Fuel

To use fuel

CAUTION: This product has a two-stroke engine. Use a mixture of gasoline and two-stroke engine oil. Make sure to use the correct quantity of oil in the mixture. Incorrect ratio of gasoline and oil can cause damage to the engine.

Husqvarna alkylate fuel

CAUTION: Do not use gasoline with an octane number less than 90 RON (87 AKI). This can cause damage to the product.

CAUTION: Do not use gasoline with more than 10% ethanol concentration (E10). This can cause damage to the product.

CAUTION: Do not use leaded gasoline. This can cause damage to the product.

We recommend Husqvarna alkylate fuel for best performance. This fuel gives less dangerous exhaust fumes compared to regular fuel. It keeps the engine clean and increases the engine life. Husqvarna alkylate fuel is not available in all commercial areas.

• Always use new unleaded gasoline with a minimum octane number of 90 RON (87 AKI) and with less than 10% ethanol concentration (E10).
- Use gasoline with a higher octane number if you frequently use the product at continuously high engine speed.
• Always use a good quality unleaded gasoline/oil mixture.

Two-stroke oil

• For best results and performance use Husqvarna two-stroke oil, which is specially formulated for our two-stroke engines.
• If Husqvarna two-stroke oil is not available, you may use another two-stroke oil of good quality that is intended for air cooled engines. Contact your dealer when you select an oil.
• Do not use two-stroke oil intended for water-cooled outboard engines, also referred to as outboard oil.
• Do not use oil intended for four-stroke engines.

Gasoline, litre	Two-stroke oil, litre
	2% (50:1)
5 0.10
10 0.20

15 0.30
20 0.40

To make the fuel mixture

Note: Always use a clean fuel container when you mix the fuel.

Note: Do not make more than 30 days quantity of fuel mixture.

1. Add half of the gasoline quantity.
2. Add the full quantity of oil.
3. Shake the fuel mixture to mix the contents.
4. Add the remaining gasoline quantity.
5. Shake the fuel mixture to mix the contents.
6. Fill the fuel tank.

To add fuel

• Always use a fuel container with an antispill valve.
- If there is some fuel on the container, remove the unwanted fuel and let the container dry.
- Make sure that the area near the fuel tank cap is clean.
- Shake the fuel container before you add the fuel mixture to the fuel tank.

To add fuel to the fuel tank

1. Stop the product.
2. Put the product on a flat surface.
3. Loosen the fuel tank cap to release the pressure in the fuel tank.
4. Remove the fuel tank cap.
5. Fill the fuel tank to 80%.
6. Tighten the fuel tank cap fully.
7. Make sure that there is no leak in the fuel tank.

To put the backpack harness on

1. Hold the shaft with the right hand and put the left strap on your left shoulder. (Fig. 48)
2. Hold the shaft with your left hand and put the right strap on your right shoulder.

Work position

• Hold the product with 2 hands.
• Hold the product on the right side of your body.
• Keep the cutting attachment below waist level.
  • Always keep the product attached to the harness.
• Keep body parts away from the hot surfaces.
• Keep body parts away from the cutting attachment.

To start the engine

If the start process is done again and again with the choke lever down, the spark plug can become wet. Refer to To start the engine if the spark plug is wet on page 21 if the engine is not easy to start.

1. Turn the fuel lever down to the vertical position (A). (Fig. 49)
2. Push the choke lever up until it stops. (Fig. 50)
3. Push the throttle lever forward and stop at the idle position. (Fig. 51)
4. Put the product on a flat surface on the ground.
5. Make sure that no objects are near the blade.
6. Hold the shaft with the left hand. (Fig. 52)
7. Put your right foot on the frame.
8. Pull the starter rope quickly with the right hand.

Note: Do not pull the starter rope to full extension and do not let go of the starter rope handle.

1. Push the choke lever down gradually until it stops.

2. Let the engine run for 2-3 minutes to become warm before operation.

To stop the engine

WARNING: Stop the engine immediately in an emergency.

CAUTION: If you stop the engine while keeping the revolution speed high, the engine could become damaged. Return the throttle lever to its original position and reduce the engine speed before stopping the engine, except in an emergency.

1. Move the throttle lever/throttle trigger to the idle position.
   a) Push the throttle lever to the idle position. (Fig. 53)
   b) Release the throttle trigger. (Fig. 54)

2. Push the engine stop button.

a) (Fig. 55)

b) (Fig. 56)

1. Turn the fuel lever up and stop at the horizontal position (B). (Fig. 49)

WARNING: The blade rotates by inertia for a while after the engine has stopped. Do not touch the blade until the engine has stopped completely.

WARNING: Do not touch the muffler or spark plug with bare hands immediately after the engine has stopped. Otherwise you may suffer burns because the muffler and the spark plug are extremely hot.

Blade thrust

A blade thrust is when the product moves to the side quickly and with force. A blade thrust occurs when the grass blade hits or catches on an object that cannot be cut. A blade thrust can eject the product or operator in all directions. There is a risk of injury to the operator and bystanders.

The risk increases in areas where it is not easy to see the material that is cut.

Do not cut with the area of the blade that is shown in black. The speed and movement of the blade can cause blade thrust. The risk increases with the thickness of the stem that is cut.

(Fig. 57)

Grass clearing with a grass blade

CAUTION: Do not use grass blades and grass knives on wood. Use grass blades and grass knives for long or heavy grass only.

• Move the product from side to side.
• Start the movement from right to left when you cut. Move the product to the right before you cut again.
• Cut with the left side of the grass blade. (Fig. 58)
• Tilt the grass blade to the left to make the grass fall in a line. This makes it easy to collect the grass.
• Keep a stable position with your feet apart.
• Move forward after each right movement and make sure that you have a stable position again before you cut again.
• Keep the support cup with a light pressure against the ground to make sure that the grass blade does not hit the ground.
• Obey these instructions to decrease the risk that cut material winds around the grass blade:
  a) Apply full throttle.
  b) Do not move the grass blade through cut material when you move the product from left to right.
• Before you collect the cut material, stop the engine and remove the product from the harness. Put the product down on the ground.

Grass trimming with a trimmer head

To trim the grass

1. Hold the trimmer head immediately above the ground at an angle. Do not push the trimmer line into the grass. (Fig. 59)
2. Decrease the length of the trimmer line by 10-12 cm / 4-4.75 in.
3. Decrease the engine speed to decrease the risk of damage to plants.
4. Use 80 % throttle when you cut grass near objects. (Fig. 60)

To clear grass with a grass blade

1. Grass blades and grass cutters must not be used on woody stems.
2. A grass blade is used for all types of tall or coarse grass.
3. The grass is cut down with a sideways, swinging movement, where the movement from right-to-left is the clearing stoke and the movement from left-to-right is the return stoke. Let the left-hand side of the blade (between 8 and 12 o'clock) do the cutting.
4. if the blade is angled to the left when clearing grass, the grass will collect in a line, which makes it easier to collect, e.g. by raking.
5. Try to work rhythmically. Stand firmly with your feet apart. Move forward after the return stoke and stand firmly again.

6. Let the support cup rest lightly against the ground. It is used to protect the blade from hitting the ground.

7. Reduce the risk of material wrapping around the blade by always work at full throttle and avoid the previously cut material during the return stoke.

8. Stop the engine, unclip the harness and place the machine on the ground before you start to collect the cut material.

To cut the grass

1. Make sure that the trimmer line is parallel to the ground when you cut the grass. (Fig. 61)
2. Do not push the trimmer head to the ground. This can cause damage to the product.
3. Move the product from side to side when you cut grass. Use full speed. (Fig. 62)

To sweep the grass

The airflow from the rotating trimmer line can be used to remove cut grass from an area.

1. Hold the trimmer head and the trimmer line parallel to the ground and above the ground.
2. Apply full throttle.
3. Move the trimmer head from side to side and sweep the grass.

WARNING: Clean the trimmer head cover each time you assemble new trimmer line to prevent unbalance and vibrations in the handles. Also do a check of the other parts of the trimmer head and clean it if necessary.

Maintenance

Introduction

WARNING: Before you do maintenance, you must read and understand the safety chapter.

For all servicing and repair work on the product, special training is necessary. We guarantee the availability of professional repairs and servicing. If your dealer is not a service agent, speak to them for information about the nearest service agent.

Maintenance schedule

Maintenance Daily Weekly Monthly
Clean the external surface. X
Examine the harness for damages. X
Do a check of the throttle trigger lockout and the throttle trigger, see To do a check of the throttle trigger lockout on page 14.	X
Make sure that the cutting attachment does not rotate at idle speed. X
Do a check of the stop switch, see To do a check of the stop switch on page 14.	X
Examine the cutting attachment guard for damages and cracks. X
Make sure that the grass blade is aligned with the center, that it is sharp and does not have damages on the blade or the center hole.	X
Examine the trimmer head for damages and cracks. Replace if it is damaged. X
Examine the handle and handlebar for damage and make sure that they are attached correctly.	X
For cutting attachments with a support cup, tighten the locking screw fully. X
For cutting attachments with a locknut, tighten the locknut fully. X
Examine the transport guard for damage and make sure that it can be attached correctly.	X
Examine the engine, the fuel tank and the fuel lines for leaks. X
Clean the air filter. Replace if it is necessary. X
Tighten nuts and screws X
Examine the fuel filter for contamination and the fuel hose for cracks and other defects. Replace if it is necessary.	X
Examine all cables and connections. X
Examine the starter and the starter rope for damages. X
Examine the vibration damping units for damages and cracks. X
Examine the spark plug, see To examine the spark plug on page 23.		X
Clean the cooling system. X
Make sure that the bevel gear is filled to 3⁄4 with grease. X
Clean the external surface of the carburetor and the area around it. X
Examine the clutch, clutch springs and the clutch drum for wear. Replace if it is necessary.			X
Replace the spark plug.			X
Lubricate the drive shaft.1			X

To start the engine if the spark plug is wet

1. Push the choke lever up and push the throttle lever near the maximum position.
2. Pull the starter rope again and again.
3. If step 1 and 2 does not help, remove the spark plug and dry the electrode.

To adjust the play of the throttle cable

1. Stop the product.
2. Push the throttle lever to the lowest speed position.
3. Loosen the locknut. (Fig. 63)
4. Turn the cable adjuster (A) to adjust the play.

a) Turn the cable adjuster clockwise to increase the play.
b) Turn the cable adjuster counterclockwise to decrease the play.

1. Make sure that the play of the throttle cable is 1-2 mm.

2. Tighten the locknut.

To clean the cooling system

CAUTION: A dirty or blocked cooling system can make the product too hot, which can cause damage to the product.

The cooling system includes:

• The cooling fins on the cylinder (A).
- The air intake (B).

(Fig. 64)

• Make sure that the cooling system is not dirty or blocked.
• Clean the cooling system with a brush weekly or more frequently if it is necessary.

To adjust the idle speed

The idle speed is adjusted at the factory before the product is supplied. An adjustment of the idle speed can become necessary because of changes in the operation conditions, for example, in the air.

WARNING: If the cutting attachment does not stop when you adjust the idle speed, speak to your servicing dealer. Do not use the product until it is correctly adjusted or repaired.

• Make sure that the throttle wire is parallel with the flexible shaft. If the throttle wire is twisted, make the throttle wire straight.
• If the shaft is bent, the play of the wire is changed. Make the shaft straight and put the product in the position you usually operate it before you adjust the idle speed.

• The idle speed is correct when the engine operates smoothly in all positions. The correct idle speed is set when the product does not stop and the cutting equipment does not rotate.

• Start the engine and operate the product at half speed for >2 minutes until the engine becomes warm.

• Turn the idle adjustment screw clockwise until the cutting attachment starts to rotate. (Fig. 65)

• Turn the idle adjustment screw counterclockwise until the cutting attachment stops and the noise from the clutch decreases.

Note: Refer to Technical data on page 25 for the recommended idle speed.

To clean the air filter

CAUTION: Always replace a damaged air filter. The wear on the engine increases with a damaged air filter. Clean the air filter at an interval of 25 hours of operation.

If you use an air filter for a long time, it cannot be fully cleaned. Replace the air filter with a new one at regular intervals.

1. Remove the air filter cover and remove the air filter. (Fig. 66)
2. Clean the air filter with compressed air.
3. Clean the inner surface of the filter cover. Use compressed air or a brush.
4. If the air filter is not clean, remove the air filter and clean it with warm water and soap.
5. Make sure that the filter is dry before you assemble the air filter again.

To apply oil to the air filter

CAUTION: Always use Husqvarna special air-filter oil. Do not use other types of oil.

WARNING: Put on protective gloves. The air-filter oil can cause skin irritation.

1. Put the air filter in a plastic bag.
2. Put the oil in the plastic bag.
3. Rub the plastic bag to supply the oil equally across the air filter.
4. Push the unwanted oil out of the air filter while in the plastic bag. (Fig. 67)

Fuel filter

WARNING: When assemble or disassemble the fuel filter, be careful not to damage the rubber packing. A damaged rubber packing or insufficient assembly of the fuel filter will cause fuel to leak.

Examine the fuel filter (A) at an interval of 25 hours of operation. If the fuel filter is clogged it must be cleaned, refer to To clean the fuel filter on page 22 for instructions. A clogged fuel filter can prevent that the rotation speed of the engine increases. A clogged fuel filter can also make unwanted speed variations occur. If the fuel filter is damaged, it must be replaced.

(Fig. 68)

To clean the fuel filter

1. Examine the fuel filter.
2. Replace the fuel filter if it is damaged.
3. If the fuel filter is clogged, remove the fuel from the fuel tank.
4. Clean the fuel filter with a brush.
5. Replace the fuel filter if you can not clean it.
6. Put the fuel filter back in the fuel tank.

Bevel gear

The bevel gear is filled to 34 with grease at the factory. Before you use the product, make sure that the grease level has not changed. Use Husqvarna special grease if it is necessary to fill up. Do not replace the grease in the bevel gear. Let servicing personnel do the repair of the bevel gear.

(Fig. 69)

To lubricate the flexible drive shaft

1. Pull up the knob and remove the drive shaft sleeve from the clutch cover. (Fig. 70)
   a) Shake or pull the drive shaft out of the drive shaft sleeve. (Fig. 71)
2. Lubricate the drive shaft. (Fig. 72)
3. Push and turn the drive shaft at the same time to put it back in the drive shaft sleeve. Keep approximately 10 mm / 0.40 in. of the drive shaft outside the edge of the drive shaft sleeve. (Fig. 73)
4. Align the hole in the drive shaft sleeve with the knob on the clutch cover. (Fig. 74)
5. Push and turn the drive shaft at the same time to connect it.

To attach and remove the locknut

WARNING: Stop the engine, use protective gloves and be careful around the sharp edges of the cutting attachment.

A locknut is used to attach some types of cutting attachments. The locknut has a left thread.

• To attach, tighten the locknut in the opposite direction to the direction of turning of the cutting attachment.
• To remove the locknut, loosen the locknut in the same direction as the cutting attachment rotates.
• To loosen and tighten the locknut, use a socket wrench with a long shaft. The arrow in the picture shows the area where you can operate the socket wrench. (Fig. 75)

WARNING: When you loosen and tighten the locknut, there is a risk of injury from the blade. You must always make sure that the blade guard prevents injury to your hand when you do this.

Note: Make sure that you can not turn the locknut by hand. Replace the nut if the nylon lining does not have a resistance of a minimum of 1.5 Nm. The locknut must be replaced after it has been put on approximately 10 times.

To examine the spark plug

CAUTION: Always use the recommended spark plug type. Incorrect spark plug type can cause damage to the product.

• Examine the spark plug if the engine is low on power, is not easy to start or does not operate correctly at idle speed.
• To decrease the risk of unwanted material on the spark plug electrodes, obey these instructions:
  a) Make sure that the idle speed is correctly adjusted.
  b) Make sure that the fuel mixture is correct. c) Make sure that the air filter is clean.
• If the spark plug is dirty, clean it and make sure that the electrode gap is correct, refer to Technical data on page 25. (Fig. 76)
• Replace the spark plug if it is necessary.

To sharpen the grass knife and grass blade

WARNING: Stop the engine. Use protective gloves.

• To sharpen the grass knife or grass blade correctly, refer to the instructions that come with the cutting attachment.
• Sharpen all edges equally to keep the balance.
• Use a single-cut flat file. (Fig. 77)

WARNING: Always discard a blade that is damaged. Do not try to make a bent or twisted blade straight and use it again.

To do maintenance every 100 hours

1. Remove the muffler.
2. Push the screwdriver into the slot and remove the unwanted material. (Fig. 78)
3. Tighten all screws and bolts. Make sure that all parts are correctly attached.
4. Make sure that the clutch lining and clutch drum is free from dirt, oil and grease. If not, wipe it of with a cloth and an oil-free and lead-free gasoline.
5. Remove the float chamber from the carburetor and clean the inside of the float chamber. (Fig. 79)

Troubleshooting

The engine does not start

Check Possible cause Procedure
Stop switch The stop switch is in the stop position.	stop position.	Let an approved service agent replace the stop switch.
Fuel tank Incorrect fuel type. Drain the fuel tank and fill with cor-rect fuel.	fuel tank and fill with cor-rect fuel.
Spark plug The spark plug is dirty or wet.	Make sure that the spark plug is dry and clean.
	The spark plug electrode gap is incorrect.	Clean the spark plug. Make sure that the electrode gap is correct. Make sure that the spark plug has a suppressor.
		Refer to technical data for correct electrode gap.
	The spark plug is loose. Tighten the spark plug.

The engine starts but stops again

Check	Possible cause Procedure
Fuel tank Incorrect fuel	type. Empty the fuel tank and fill it with correct	fuel.
Air filter The air filter is	clogged. Clean the air filter.

Transportation and storage

• Let the product cool before transportation or storage.
• Remove the spark plug cap before long-term storage.
• Attach the product during transportation. Make sure that it cannot move.

• Make sure that there is no risk of fuel leaks, fuel fumes, sparks or flames during transportation and storage.

• Attach the transport guard during transportation and storage.

• Clean and do servicing on the product before long-term storage.

Technical data

Technical data

	531RB 541RB
Engine
Cylinder displacement, cm ^3	33.6 41.5
Cylinder bore, mm 36 40
Stroke, mm 33 33
Idle speed, rpm 2500 ± 200 2500 ± 200
Recommended max speed, rpm 12000 12000
Max. engine output, according to ISO 8893, kW @ rpm 1.1/7000-7500 1.47/7000-7500
Catalytic converter muffler No No
Ignition system
Spark plug Champion RCJ-6Y Champion RCJ-6Y
Electrode gap, mm 0.6-0.7 0.6-0.7
Fuel and lubrication system
Fuel tank capacity, litre/cm ^2	1.3/119.1	1.3/119.1
Carburetor
Type	Float, piston valve	Float, piston valve
Weight
Without fuel, cutting attachment and guard, kg	9.0	9.0
Sound levels ^2
Equivalent sound pressure level at the operator's ear, measured according to EN ISO 11806 and ISO 22868, dB(A), min./max.:	87 87
Vibration levels ^3
Equivalent vibration levels (ahv,eq) at handles, measured according to EN ISO 11806 and ISO 22867, m/s ^2 :
Equipped with Grass blade, grip/handle	10 10

Accessories

Accessories

Approved accessories Accessory type	Cutting attachment guard, art. no.
Grass blade/grass cutter Multi 300-3 (Ø 300, 3 teeth) 577 32 97-01
Grass 255-4 (Ø 255, 4 teeth)
Trimmer head PT104 (M10 x 1.25 L) 588 55 02-02
Support cup Fixed

Contenido

Introducción.... 27

Seguridad.... 28

Montaje.... 32

Original instructions