MTD 41ADY90C401 - Brush cutter

41ADY90C401 - Brush cutter MTD - Free user manual and instructions

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USER MANUAL 41ADY90C401 MTD

2-Cycle Trimmer/ Brushcutter

Model YM90

MTD 41ADY90C401 - 2-Cycle Trimmer/ Brushcutter - 1

IMPORTANT: Read safety rules and instructions carefully before operating equipment.

TABLE OF CONTENTS

Content

Rules for Safe Operation 3

Know Your Trimmer 7

Assembly Instructions 8

Oil and Fuel Information 11

Starting/Stopping Instructions 12

Operating Instructions 13

Maintenance and Repair Instructions 16

Cleaning and Storage 21

Troubleshooting 22

Specifications 23

Warranty 26

Parts List . Inside Back Cover

FINDING MODEL NUMBER

This Operator's Manual is an important part of your new trimmer. It will help you assemble, prepare and maintain the unit for best performance. Please read and understand what it says.

MTD 41ADY90C401 - FINDING MODEL NUMBER - 1

Before you start assembling your new equipment, please locate the model plate on the unit and copy the information from it onto the space provided below. The information on the model plate is very important if you need help from our Customer Support Department or an authorized dealer.

  • The model number is located on the engine. A sample model plate is shown and explained below. For future reference, please copy the model number and the serial number of the equipment in the space provided.

MTD 41ADY90C401 - FINDING MODEL NUMBER - 2

Copy the model and parent

part number here:

Copy the serial number here:

CALLING CUSTOMER SUPPORT

If you have difficulty assembling this product or have any questions regarding the controls, operation or maintenance of this unit, please call the Customer Support Department.

MTD 41ADY90C401 - CALLING CUSTOMER SUPPORT - 1

Call 1- (800)-345-8746, or 1- (800)-668-1238 in Canada, to reach a Customer Support representative. Please have your unit's model number and serial number ready when you call. You will be asked to enter the serial number in order to process your call. This information is explained above.

VISIT OUR WEB SITE

Visit our web site at www.yardman.com for more information about our quality Yard Man products, customer service, parts, tips, literature and more.

SPARK ARRESTOR

NOTE: For users on U.S. Forest Land and in the states of California, Maine, Oregon and Washington. All U.S. Forest Land and the state of California (Public Resources Codes 4442 and 4443), Oregon and Washington require, by law that certain internal combustion engines operated on forest brush and/or grass-covered areas be equipped with a spark arrester, maintained in effective working order, or the engine be constructed, equipped and maintained for the prevention of fire. Check with your state or local authorities for regulations pertaining to these requirements. Failure to follow these requirements could subject you to liability or a fine. This unit is factory equipped with a spark arrester. If it requires replacement, ask your LOCAL SERVICE DEALER to install the accessory part #182747 Spark Arrestor.

WARNING!

Read the Operator's Manual and follow all warnings and safety instructions. Failure to do so can result in serious injury to the operator and/or bystanders.

FOR QUESTIONS, CALL 1-800-345-8746 IN U.S. OR 1-800-668-1238 in CANADA

SECTION 1: IMPORTANT SAFE OPERATION PRACTICES

MTD 41ADY90C401 - SECTION 1: IMPORTANT SAFE OPERATION PRACTICES - 1

The purpose of safety symbols is to attract your attention to possible dangers. The safety symbols and their explanations deserve your careful attention and understanding. The safety warnings do not by themselves eliminate any danger. The instructions or warnings they give are not substitutes for proper accident prevention measures.

MTD 41ADY90C401 - SECTION 1: IMPORTANT SAFE OPERATION PRACTICES - 2

SAFETY ALERT SYMBOL: Indicates danger, warning, or caution. Attention is required in order to avoid serious personal injury. May be used in conjunction with other symbols or pictographs.

NOTE: Advises you of information or instructions vital to the operation or maintenance of the equipment.

MTD 41ADY90C401 - SECTION 1: IMPORTANT SAFE OPERATION PRACTICES - 3

DANGER: Failure to obey a safety warning will result in serious injury to yourself or to others. Always follow the safety precautions to reduce the risk of fire, electric shock and personal injury.

MTD 41ADY90C401 - SECTION 1: IMPORTANT SAFE OPERATION PRACTICES - 4

WARNING: Failure to obey a safety warning can result in injury to yourself and others. Always follow the safety precautions to reduce the risk of fire, electric shock and personal injury.

MTD 41ADY90C401 - SECTION 1: IMPORTANT SAFE OPERATION PRACTICES - 5

CAUTION: Failure to obey a safety warning may result in property damage or personal injury to yourself or to others. Always follow the safety precautions to reduce the risk of fire, electric shock and personal injury.

SECTION 1a: RULES FOR SAFE OPERATION

California Proposition 65 Warning:

MTD 41ADY90C401 - SECTION 1a: RULES FOR SAFE OPERATION - 1

WARNING

MTD 41ADY90C401 - WARNING - 1

THE ENGINE EXHAUST FROM THIS PRODUCT CONTAINS CHEMICALS KNOWN TO THE STATE OF CALIFORNIA TO CAUSE CANCER, BIRTH DEFECTS OR OTHER REPRODUCTIVE HARM.

READ ALL INSTRUCTIONS

MTD 41ADY90C401 - READ ALL INSTRUCTIONS - 1

WARNING: When using the unit, you must follow the safety rules. For your own safety and that of bystanders, please read these instructions before operating the unit. Please keep the instructions for later use.

Before Operating

  • Read the instructions carefully. Be familiar with the controls and proper use of the unit.
  • Do not operate this unit when tired, ill or under the influence of alcohol, drugs or medication.

  • Children under the age of 15 must not use the unit; teens may operate the unit with adult guidance.

  • Inspect the unit before use. Replace damaged parts. Check for fuel leaks. Make sure all fasteners are in place and secure. Replace cutting attachment parts that are cracked, chipped or damaged in any way. Make sure the cutting attachment is properly installed and securely fastened. Be sure that the cutting attachment shield is properly attached, and positioned as recommended. Failure to do so can result in personal injury to the operator and bystanders, as well as damage to the unit.
  • Use only 0.095-inch (2.41 mm) diameter Genuine Factory Parts™ replacement line. Never use metal-reinforced line, wire, chain or rope. These can break off and become dangerous projectiles.
  • Be aware of risk of injury to the head, hands and feet.
  • Clear the area to be cut before each use. Remove rocks, broken glass, nails, wire, string and other objects which may be thrown or become entangled in the cutting attachment. Clear the area of children, bystanders and pets; keep them outside a 50-foot (15 m.) radius, at a minimum. Even then, they are still at risk from thrown objects. Encourage bystanders to wear eye protection. If you are approached, stop the unit immediately.
  • Squeeze the throttle control and check that it returns automatically to the idle position. Make all adjustments or repairs before using the unit.

SafetyWarnings for Gas Trimmers

MTD 41ADY90C401 - SafetyWarnings for Gas Trimmers - 1

WARNING: Gasoline is highly flammable, and its vapors can explode if ignited. Take the following precautions:

  • Store fuel only in containers specifically designed and approved for the storage of such materials.
  • Always stop the engine and allow it to cool before filling the fuel tank. Never remove the fuel tank cap or add fuel when the engine is hot. Never operate the unit without the fuel cap securely in place. Loosen the fuel tank cap slowly to relieve any pressure in the tank.
  • Add fuel in a clean, well-ventilated outdoor area where there are no sparks or flames. Remove the fuel cap slowly, and only after the engine stops. Do not smoke while fueling or mixing fuel. Wipe up any spilled fuel from the unit immediately.
  • Avoid creating a source of ignition for spilled fuel. Do not start the engine until fuel vapors dissipate.
  • Move the unit at least 30 feet (9.1 m) from the fueling source and site before starting the engine. Do not smoke. Keep sparks and open flames away from the area while adding fuel or operating the unit.

While Operating

  • Never start or run the unit inside a closed room or building. Breathing exhaust fumes can be fatal. Operate this unit only in a well-ventilated outdoor area.

  • Wear safety glasses or goggles that meet ANSI Z87.1 standards and are marked as such. Wear ear/hearing protection when operating this unit. Wear a face or dust mask if the operation is dusty.

  • Wear heavy long pants, boots, gloves and a long sleeve shirt. Do not wear loose clothing, jewelry, short pants, sandals or go barefoot. Secure hair above shoulder level.
  • The cutting attachment shield must always be in place while operating the unit. Do not operate unit without both trimming lines extended, and the proper line installed. Do not extend the trimming line beyond the length of the shield.
  • This unit has a clutch. The cutting attachment remains stationary when the engine is idling. If it does not, have the unit adjusted by an authorized service technician.
  • Adjust the J-handle to your size in order to provide the best grip.
  • Be sure the cutting attachment is not in contact with anything before starting the unit.
  • Use the unit only in daylight or good artificial light.
  • Avoid accidental starting. Remain in the starting position whenever pulling the starter rope. The operator and unit must be in a stable position while starting. Refer to Starting/Stopping Instructions.
  • Use the right tool. Only use this tool for its intended purpose.
  • Do not overreach. Always keep proper footing and balance.
  • Always hold the unit with both hands when operating. Keep a firm grip on both handles or grips.
  • Keep hands, face, and feet at a distance from all moving parts. Do not touch or try to stop the cutting attachment when it rotates.
  • Do not touch the engine, gear housing or muffler. These parts get extremely hot from operation, even after the unit is turned off.
  • Do not operate the engine faster than the speed needed to cut, trim or edge. Do not run the engine at high speed when not cutting.
  • Always stop the engine when cutting is delayed or when walking from one cutting location to another.
  • If you strike or become entangled with a foreign object, stop the engine immediately and check for damage. Do not operate before repairing damage. Do not operate the unit with loose or damaged parts.
  • Stop the unit, switch the engine to off, and disconnect the spark plug for maintenance or repair.
  • Use only Genuine Factory Parts™ replacement parts and accessories for this unit. These are available from your authorized service dealer. Use of any unauthorized parts or accessories could lead to serious injury to the user, damage to the unit, and a voided warranty.
  • Keep unit clean of vegetation and other materials. They may become lodged between the cutting attachment and shield.

  • To reduce fire hazard, replace a faulty muffler and spark arrestor. Keep the engine and muffler free from grass, leaves, excessive grease or carbon build up.

While Operating with the Cutting Blade

  • Read and understand all safety warnings before operating this unit.
    Always use the shoulder harness when using the brush blade accessory.
  • Keep the J-handle between the operator and cutting attachment or blade at all times.
  • NEVER cut with the cutting blade located over 30 inches (76 cm) or more above the ground level.
  • Blade thrust may occur when the spinning blade contacts an object that it does not immediately cut. Blade thrust can be violent enough to cause the unit and/or operator to be propelled in any direction, and possibly lose control of the unit. Blade thrust can occur without warning if the blade snags, stalls or binds. This is more likely to occur in areas where it is difficult to see the material being cut.
  • For operation with the brush blade, do not cut anything thicker than 1/2 inch or a violent kickback could occur.
  • Do not attempt to touch or stop the blade when it is rotating.
  • A coasting blade can cause injury while it continues to spin after the engine is stopped or the throttle trigger is released. Maintain proper control until the blade has completely stopped rotating.
  • Do not run the unit at high speed when not cutting.
  • If you strike or become entangled with a foreign object, stop the engine immediately and check for damage. Have any damage repaired before attempting further operations. Do not operate unit with a bent, cracked or dull blade. Discard blades that are bent, warped, cracked or broken.

  • Do not sharpen the cutting blade. Sharpening the blade can cause the blade tip to break off while in use. This can result in severe personal injury. Replace the blade.

  • Do not use the cutting blade for edging or as an edge, severe personal injury to yourself or others can occur. Use the cutting blade only for the purpose as described in this manual.
  • Stop the engine IMMEDIATELY if you feel excessive vibration. Vibration is a sign of trouble. Inspect thoroughly for loose nuts, bolts or damage before continuing. Repair or replace affected parts as necessary.

After Use

  • Clean cutting blades with a household cleaner to remove any gum buildup. Oil the blade with machine oil to prevent rust.
  • Lock up and store the cutting blade in an appropriate area to protect the blade from unauthorized use or damage.

Other SafetyWarnings

  • Never store a fueled unit inside a building where fumes may reach an open flame or spark.
  • Allow the engine to cool before storing or transporting. Be sure to secure the unit while transporting.
  • Store the unit in a dry area, locked up or up high to prevent unauthorized use or damage, out of the reach of children.
  • Never douse or squirt the unit with water or any other liquid. Keep handles dry, clean and free from debris. Clean after each use, see Cleaning and Storage instructions.
  • Keep these instructions. Refer to them often and use them to instruct other users. If you loan someone this unit, also loan them these instructions.

SAVE THESE INSTRUCTIONS

SECTION 1b: SAFETY & INTERNATIONAL SYMBOLS

This operator's manual describes safety and international symbols and pictographs that may appear on this product. Read the operator's manual for complete safety, assembly, operating and maintenance and repair information.

SYMBOL MEANING

MTD 41ADY90C401 - SYMBOL MEANING - 1

- SAFETY ALERT SYMBOL

Indicates danger, warning or caution. May be used in conjunction with other symbols or pictographs.

SYMBOL MEANING

MTD 41ADY90C401 - SYMBOL MEANING - 1

ON/OFF STOP CONTROL

OFF or STOP

MTD 41ADY90C401 - ON/OFF STOP CONTROL - 1

WARNING - READ OPERATOR'S MANUAL

Read the operator's manual(s) and follow all warnings and safety instructions.

Failure to do so can result in serious injury to the operator and/or bystanders.

MTD 41ADY90C401 - WARNING - READ OPERATOR'S MANUAL - 1

- THROWN OBJECTS AND ROTATING CUTTER CAN CAUSE SEVERE INJURY

WARNING: Do not operate without the cutting attachment shield in place. Keep away from the rotating cutting attachment.

MTD 41ADY90C401 - - THROWN OBJECTS AND ROTATING CUTTER CAN CAUSE SEVERE INJURY - 1

- WEAR EYE AND HEARING PROTECTION

WARNING: Thrown objects and loud noise can cause severe eye injury and hearing loss. Wear eye protection meeting ANSI Z87.1 standards and ear protection when operating this unit. Use a full face shield when needed.

MTD 41ADY90C401 - - WEAR EYE AND HEARING PROTECTION - 1

- HOT SURFACE WARNING

Do not touch a hot muffler, gear housing or cylinder. You may get burned. These parts get extremely hot from operation.

They remain hot for a short time after the unit is turned off.

MTD 41ADY90C401 - - HOT SURFACE WARNING - 1

- KEEP BYSTANDERS AWAY

WARNING: Keep all bystanders, especially children and pets, at least 50 feet (15 m) from the operating area.

MTD 41ADY90C401 - - KEEP BYSTANDERS AWAY - 1

SHARP BLADE

WARNING: Sharp blade on cutting attachment shield. To prevent serious injury, do not touch line cutting blade.

MTD 41ADY90C401 - SHARP BLADE - 1

- UNLEADED FUEL

Always use clean, fresh unleaded fuel.

MTD 41ADY90C401 - - UNLEADED FUEL - 1

- BRUSHCUTTERS • REPLACE DULL BLADE

Do not sharpen the cutting blade. Sharpening the blade can cause the blade tip to break off while in use. This can result in severe personal injury.

MTD 41ADY90C401 - - BRUSHCUTTERS • REPLACE DULL BLADE - 1

OIL

Refer to operator's manual for the proper type of oil.

MTD 41ADY90C401 - OIL - 1

-TRIMMER/BRUSHCUTTER SAFETY

WARNING: Thrown objects and rotating cutter can cause severe injury. Keep bystanders, especially children and pets, at least 50 feet (15 m) away from the cutting area. The cutting attachment shield must be used when using the trimmer cutting attachment.

MTD 41ADY90C401 - -TRIMMER/BRUSHCUTTER SAFETY - 1

ON/OFF STOP CONTROL

ON / START / RUN

Applications

As a trimmer:

Cutting grass and light weeds
- Edging
- Decorative trimming around trees, fences, etc.

As a brushcutter:

Cutting weeds and light bush of up to 1/2 inch in diameter

Other optional accessories may be used with the YM90. Refer to Operating the EZ-Link System for a list of add-ons.

MTD 41ADY90C401 - As a brushcutter: - 1

SECTION 3: ASSEMBLY INSTRUCTIONS

Installing and Adjusting the J-handle

  1. Place the J-handle between the top and middle clamp pieces. See Figure 1.

MTD 41ADY90C401 - Installing and Adjusting the J-handle - 1
Figure 1

  1. While holding the three pieces together, install the four (4) screws through the top clamp and into middle clamp.

NOTE: The holes in the top and middle clamp will line up only when assembled correctly.

  1. Place the clamps and the J-handle over the shaft housing and onto the bottom clamp.
  2. Hold each hex nut in the bottom clamp recess with a finger. Start screws with a large Phillips screwdriver. Do not tighten until you make the handle adjustment.
  3. Slide the J-handle in or out until the arrow/white line on the decal touches the clamp assembly. See Figure 2. You must first loosen the screws if the handle is pre-installed.

MTD 41ADY90C401 - Installing and Adjusting the J-handle - 2
Figure 2

  1. While holding the unit in the operating position, arrange the J-handle to the location that provides you the best grip. See Figure 3.

MTD 41ADY90C401 - Installing and Adjusting the J-handle - 3
Figure 3

  1. Tighten the clamp screws evenly, until the J-handle is secure.

Install the Harness

MTD 41ADY90C401 - Install the Harness - 1

WARNING: Always use the shoulder harness when using the cutting blade to avoid serious personal injury.

  1. Push the strap through the center of the buckle.
  2. Pull the strap over the cross bar and down through the slot in the buckle. See Figure 4.
  3. Put the harness on over head and onto shoulder. Snap it on to the support fitting. See Figure 5.
  4. Adjust length to fit the operator's size. Pull tab to lengthen, pull strap to shorten. See Figure 6.

MTD 41ADY90C401 - Install the Harness - 2

MTD 41ADY90C401 - Install the Harness - 3
Figure 4
Figure 5

MTD 41ADY90C401 - Install the Harness - 4
Figure 6

Remove and Install the Cutting Attachment Shield

Remove the cutting attachment shield when using the unit as a brushcutter

MTD 41ADY90C401 - Remove and Install the Cutting Attachment Shield - 1

WARNING: The cutting attachment shield should NOT be installed when operating the unit with a blade. Remove the cutting attachment shield before removing or installing the blade.

Remove the cutting attachment shield from the shield mount by removing the three (3) screws with a flat blade screwdriver. See Figure 7. Store parts for future use.

SECTION 3: ASSEMBLY INSTRUCTIONS

MTD 41ADY90C401 - SECTION 3: ASSEMBLY INSTRUCTIONS - 1
Figure 7

Install the cutting attachment shield when using the unit as a grass trimmer

MTD 41ADY90C401 - SECTION 3: ASSEMBLY INSTRUCTIONS - 2

WARNING: To avoid serious personal injury, the cutting attachment shield MUST be in place at all times while operating the unit as a grass trimmer.

Install the cutting attachment shield on the shield mount by inserting the three (3) screws into the shield mount. Tighten securely with a flat blade screwdriver. See Figure 7.

Remove the Cutting Attachment & Install the Cutting Blade

NOTE: To make cutting blade removal and installation easier, place the unit on the ground or on a work bench.

Remove the Cutting Attachment Shield

See Remove and Install the Cutting Attachment Shield.

MTD 41ADY90C401 - Remove the Cutting Attachment Shield - 1

WARNING: The gear housing gets hot with use. It can result in injury to the operator. The housing remains hot for a short time even after the unit is turned off. Do not touch the gear housing until it has cooled.

Remove the Cutting Attachment

  1. Align the shaft bushing hole with the locking rod slot and insert the locking rod into the shaft bushing hole. See Figure 8.

MTD 41ADY90C401 - Remove the Cutting Attachment - 1
Figure 8

  1. Hold the locking rod in place by grasping it next to the boom of the unit. See Figure 9.
  2. While holding the locking rod, remove the cutting attachment by turning it clockwise off of the output shaft. See Figure 10. Store the cutting attachment for future use.

NOTE: The blade retainer under the cutting attachment will be used when installing the cutting blade.

MTD 41ADY90C401 - Remove the Cutting Attachment - 2
Figure 9

MTD 41ADY90C401 - Remove the Cutting Attachment - 3
Figure 10

Install the Cutting Blade

MTD 41ADY90C401 - Install the Cutting Blade - 1

WARNING: To avoid serious personal injury, always wear gloves while handling or installing the blade.

  1. Place the cutting blade on the output shaft bushing. See Figure 11.

MTD 41ADY90C401 - Install the Cutting Blade - 2
Figure 11

SECTION 3: ASSEMBLY INSTRUCTIONS

  1. Make sure that the cutting blade is centered on the pilot step and sitting flat against the output shaft bushing. See Figure 12.

MTD 41ADY90C401 - SECTION 3: ASSEMBLY INSTRUCTIONS - 1

WARNING: If the cutting blade is off-center, the unit will vibrate and the blade may fly off, causing possible serious personal injury.

MTD 41ADY90C401 - SECTION 3: ASSEMBLY INSTRUCTIONS - 2
Figure 12

  1. Align the shaft bushing hole with the locking rod slot and insert the locking rod into the bushing hole. See Figure 8.
  2. Put the blade retainer and nut on the output shaft. Make sure that the blade is installed correctly.
  3. Tighten nut counterclockwise against the blade while holding the locking rod:
  4. If using a torque wrench and an 5/8 inch socket tighten to: 325 - 335 in·lb, 27 - 28 ft·lb, 37 - 38 N·m.
  5. Without a torque wrench, use a 5/8 inch closed-end or socket wrench, turning the nut until the blade retainer is snug against the shaft bushing. Make sure that the blade is installed correctly, then rotate the nut an additional 1/4 to 1/2 turn counterclockwise. See Figure 13.

MTD 41ADY90C401 - SECTION 3: ASSEMBLY INSTRUCTIONS - 3

  1. Remove the locking rod from the locking rod slot.

MTD 41ADY90C401 - SECTION 3: ASSEMBLY INSTRUCTIONS - 4

WARNING: To avoid serious personal injury or damage to the unit, do not start or operate this unit with the locking rod in the locking rod slot.

MTD 41ADY90C401 - SECTION 3: ASSEMBLY INSTRUCTIONS - 5

WARNING: Do not sharpen the cutting blade. Sharpening the blade can cause the blade tip to break off while in use. This can result in severe personal injury. Replace the blade.

Remove the Cutting Blade & Install the Cutting Attachment

MTD 41ADY90C401 - Remove the Cutting Blade & Install the Cutting Attachment - 1

WARNING: To avoid serious personal injury, always wear gloves while handling or installing the blade.

Remove the Cutting Blade

  1. Align the shaft bushing hole with the locking rod slot and insert the locking rod into the bushing hole. See Figure 8.
  2. Hold the locking rod in place by grasping it next to the boom of the unit. See Figure 14.
  3. While holding the locking rod, loosen the nut on the blade by turning it clockwise with a 5/8 inch closed-end or socket wrench. See Figure 14.

MTD 41ADY90C401 - Remove the Cutting Blade - 1
Figure 14

  1. Remove the nut, blade retainer and blade. Store the nut and blade together for future use in a secure place. Store out of children's reach.

Install the Cutting Attachment

  1. Align the shaft bushing hole with the locking rod slot and insert the locking rod into the shaft bushing hole. See Figure 8. Place the blade retainer on the output shaft with the flat surface against the output shaft bushing. See Figure 15. Screw the cutting attachment counterclockwise onto the output shaft. Tighten securely.

NOTE: The blade retainer must be installed on the output shaft in the position shown for the cutting attachment to work correctly.

MTD 41ADY90C401 - Install the Cutting Attachment - 1
Figure 15

  1. Remove the locking rod.
  2. Install the cutting attachment shield. Refer to Remove and Install the Cutting Attachment Shield.

MTD 41ADY90C401 - Install the Cutting Attachment - 2

WARNING: To avoid serious personal injury, the cutting head guard MUST be in place at all times while operating the unit as a trimmer.

SECTION 4: OIL AND FUEL INFORMATION

Oil and Fuel Mixing Instructions

Old and/or improperly mixed fuel is the main reason for improper unit performance. Be sure to use fresh, clean unleaded fuel. Follow the instructions carefully for the proper fuel/oil mixture.

Definition of Blended Fuels

Today's fuels are often a blend of gasoline and oxygenates such as ethanol, methanol, or MTBE (ether). Alcohol-blended fuel absorbs water. As little as 1% water in the fuel can make fuel and oil separate. It forms acids when stored. When using alcohol-blended fuel, use fresh fuel (less than 60 days old).

Using Blended Fuels

If you choose to use a blended fuel, or its use is unavoidable, follow recommended precautions:

  • Always use fresh fuel mix per your operator's manual
  • Always agitate the fuel mix before fueling the unit
  • Drain the tank and run the engine dry before storing the unit

Using Fuel Additives

The bottle of 2-cycle oil that came with your unit contains a fuel additive which will help inhibit corrosion and minimize the formation of gum deposits. It is recommended that you use only our 2-cycle oil with this unit.

If unavailable, use a good 2-cycle oil designed for air-cooled engines along with a fuel additive, such as STA-BIL® Gas Stabilizer or an equivalent. Add 0.8 oz. (23 ml.) of fuel additive per gallon of fuel according to the instructions on the container. NEVER add fuel additives directly to the unit's fuel tank.

MTD 41ADY90C401 - Using Fuel Additives - 1

CAUTION: For proper engine operation and maximum reliability, pay strict attention to the oil and fuel mixing instructions on the 2-cycle oil container. Using improperly mixed fuel can severely damage the engine.

Thoroughly mix the proper ratio of 2-cycle engine oil with unleaded gasoline in a separate fuel can. Use a 40:1 fuel/oil ratio. Do not mix them directly in the engine fuel tank. See the table below for specific gas and oil mixing ratios.

NOTE: One gallon (3.8 liters) of unleaded gasoline mixed with one 3.2 oz. (95 ml.) bottle of 2-cycle oil makes a 40:1 fuel/oil ratio.

MTD 41ADY90C401 - Using Fuel Additives - 2
UNLEADED GAS

+

MTD 41ADY90C401 - Using Fuel Additives - 3
2-CYCLE OIL

1 US. GALLON + 3.2 FL. OZ. (3.8 LITERS) (95 ml)

1 LITER + 25 ml

MIXING RATIO - 40:1

MTD 41ADY90C401 - Using Fuel Additives - 4

WARNING: Gasoline is extremely flammable. Ignited vapors may explode. Always stop the engine and allow it to cool before filling the fuel tank. Do not smoke while filling the tank. Keep sparks and open flames at a distance from the area.

MTD 41ADY90C401 - Using Fuel Additives - 5

WARNING: Remove fuel cap slowly to avoid injury from fuel spray. Never operate the unit without the fuel cap securely in place.

MTD 41ADY90C401 - Using Fuel Additives - 6

WARNING: Add fuel in a clean, well-ventilated outdoor area. Wipe up any spilled fuel immediately. Avoid creating a source of ignition for spilled fuel. Do not start the engine until fuel vapors dissipate.

NOTE: Dispose of the old fuel/oil mix in accordance to Federal, State and Local regulations.

SECTION 5: STARTING/STOPPING INSTRUCTIONS

MTD 41ADY90C401 - SECTION 5: STARTING/STOPPING INSTRUCTIONS - 1

WARNING: Operate this unit only in a well-ventilated outdoor area. Carbon monoxide exhaust fumes can be lethal in a confined area.

MTD 41ADY90C401 - SECTION 5: STARTING/STOPPING INSTRUCTIONS - 2

WARNING: Avoid accidental starting. Make sure you are in the starting position when pulling the starter rope. See Figure 18. To avoid serious injury, the operator and unit must be in a stable position while starting.

To avoid serious personal injury, ensure any Add-On being used is installed correctly and secure before starting unit.

Starting Instructions

IF... You are starting a warm engine, begin at step 4.
1. Mix gas with oil. Fill fuel tank with fuel/oil mixture. See Oil and Fuel Mixing Instructions.
2. Make sure the On/Off Stop Control is in the ON (I) position. See Figure 16.
3. Fully press and release the primer bulb 10 times, slowly, until FUEL IS VISIBLE IN THE PRIMER BULB. See Figure 17. If you can't see fuel in the bulb, press and release the bulb as many times as it takes before you can see fuel in it.
4. Push the EZ-Start™ Lever to the left until it clicks and locks into place. See Figure 17.
5. With the unit in the starting position, DO NOT SQUEEZE THE THROTTLE CONTROL. See Figure 18. Pull the starter rope 5 times briskly, making sure the EZ-Start™ lever is pushed to the left.

IF... The engine does not start, go back to step 3.
IF... The engine starts to run before the fifth pull, go to step 6.
IF... The outside temperature or engine temperature exceeds 90^ and the engine fails to start after 5 pulls, fully squeeze the throttle control and pull the starter rope briskly 3 to 8 more times. The engine should start within these pulls.
NOTE: When starting, the EZ-Start™ Lever will automatically click off when you squeeze the throttle control.
6. When the engine starts, squeeze the throttle control to warm up the engine for 5 to 10 seconds. The EZ-Start™ Lever will click off automatically. See Figure 17.
IF... The engine stalls while squeezing the throttle, go back to step 4.
IF... The engine stalls before you squeeze the throttle control, hold the throttle control and pull the starter rope until the trimmer starts.

MTD 41ADY90C401 - Starting Instructions - 1
Figure 16

MTD 41ADY90C401 - Starting Instructions - 2
Figure 17

MTD 41ADY90C401 - Starting Instructions - 3
Figure 18

Stopping Instructions

  1. Release your hand from the throttle control. See Figure 18. Allow the engine to cool down by idling.
  2. Push and hold the On/Off Stop Control in the OFF (O) position until the engine stops running. See Figure 16

SECTION 6: OPERATING INSTRUCTIONS

The EZ-Link™ system enables the use of these optional Add-Ons:

Blower/Vacuum BV720r

Cultivator GC720r

Edger LE720r

Hedge Trimmer HS720r

Snow Thrower ST720r

Straight Shaft Trimmer SS725r

Tree Pruner TP720r

Turbo Blower . TB720r

MTD 41ADY90C401 - Operating the EZ-Link™ System - 1

WARNING: Read and understand the operator's manual for each add-on prior to operation.

Removing the Cutting Attachment or Add-Ons

  1. Turn the knob counterclockwise to loosen. See Figure 19.
  2. Press and hold the release button. See Figure 19.
  3. While firmly holding the upper shaft housing, pull the cutting attachment or add-on straight out of the EZ-Link™ coupler. See Figure 20.

Installing the Cutting Attachment or Add-On

MTD 41ADY90C401 - Installing the Cutting Attachment or Add-On - 1

WARNING: To avoid serious personal injury and damage to the unit, shut off the unit before removing or installing add-ons.

NOTE: Place the unit on the ground or on a work bench to make add-on installation or removal easier.

  1. Turn knob counterclockwise to loosen.

MTD 41ADY90C401 - Installing the Cutting Attachment or Add-On - 2
Figure 19

  1. While firmly holding the add-on, push it straight into the EZ-Link™ coupler. See Figure 20.

NOTE: Aligning the release button with the guide recess will help installation. See Figure 19.

MTD 41ADY90C401 - Installing the Cutting Attachment or Add-On - 3
Figure 20

  1. Turn the knob clockwise to tighten. See Figure 21.

MTD 41ADY90C401 - Installing the Cutting Attachment or Add-On - 4

CAUTION: Lock the release button in the primary hole and securely tighten the knob before operating this unit

MTD 41ADY90C401 - Installing the Cutting Attachment or Add-On - 5
Figure 21

MTD 41ADY90C401 - Installing the Cutting Attachment or Add-On - 6

CAUTION: The cutting attachment and add-ons with the EZ-Link™ system are to be used in the primary hole unless stated otherwise in the specific add-ons operator's manual. Using the wrong hole could lead to personal injury or damage to the unit.

For edging (when using the line head cutting attachment with EZ-Link™ models), lock the release button of the cutting attachment into the 90^ edging hole or the 180^ edging hole. See Figure 21.

SECTION 6: OPERATING INSTRUCTIONS

Holding the Trimmer

MTD 41ADY90C401 - Holding the Trimmer - 1

WARNING: Always wear eye, hearing, foot and body protection to reduce the risk of injury when operating this unit.

Before operating the unit, stand in the operating position. See Figure 22. Check for the following:

  • The operator is wearing eye protection and proper clothing
  • With a slightly-bent right arm, the operator's right hand is holding the shaft grip
  • The operator's left arm is straight, the left hand holding the J-handle
  • The unit is at waist level
  • The cutting attachment is parallel to the ground and easily contacts the grass without the need to bend over

Once you are in the operating position, hook the shoulder strap to the unit.

MTD 41ADY90C401 - Holding the Trimmer - 2
Figure 22

Adjusting Trimming Line Length

The Bump Head™ cutting attachment allows you to release trimming line without stopping the engine. To release more line, lightly tap the cutting attachment on the ground while operating the trimmer at high speed. See Figure 23.

NOTE: Always keep the trimming line fully extended. Line release becomes more difficult when the cutting line gets shorter.

MTD 41ADY90C401 - Adjusting Trimming Line Length - 1
Figure 23

Each time the head is bumped, about 1 inch (25.4 mm) of trimming line releases. A blade in the cutting attachment shield will cut the line to the proper length if any excess line is released.

For best results, tap the bump knob on bare ground or hard soil. If you attempt a line release in tall grass, the engine may stall. Always keep the trimming line fully extended. Line release becomes more difficult when the cutting line gets shorter.

NOTE: Do not rest the bump knob on the ground while the unit is running.

MTD 41ADY90C401 - Adjusting Trimming Line Length - 2

CAUTION: Do not remove or alter the line cutting blade assembly. Excessive line length may make the unit overheat.

Some line breakage will occur from:

  • Entanglement with foreign matter
    Normal line fatigue
    An attempt to cut thick, stalky weeds
    Forcing the line into objects such as walls or fence posts

Tips for Best Trimming Results

  • For best trimming results, operate unit at full throttle.
  • Keep the cutting attachment parallel to the ground.
  • Do not force the cutting attachment. Allow the tip of the line to do the cutting, especially along walls. Cutting with more than the tip will reduce cutting efficiency and may overload the engine.
  • Cut grass over 8 inches (200 mm) tall by working from top to bottom in small increments to avoid premature line wear or engine drag.
  • Cut from left to right whenever possible. Cutting to the right improves the unit's cutting efficiency. Clippings are thrown away from the operator.
  • Slowly move the trimmer into and out of the cutting area at the desired height. Move either in a forward-to-backward or side-to-side motion. Cutting shorter lengths produces the best results.
  • Trim only when grass and weeds are dry.
    The life of your cutting line is dependent upon:

Following the trimming techniques
What vegetation is being cut
Where vegetation is cut

For example, the line will wear faster when trimming against a foundation wall as opposed to trimming around a tree.

SECTION 6: OPERATING INSTRUCTIONS

Decorative Trimming

Decorative trimming refers to the removal of vegetation around trees, posts, fences and more.

Rotate the whole unit so that the cutting attachment is at a 30^ angle to the ground. See Figure 24.

MTD 41ADY90C401 - Decorative Trimming - 1
Figure 24

Using the Cutting Blade

MTD 41ADY90C401 - Using the Cutting Blade - 1

WARNING: Always wear eye, hearing, foot, body protection and the shoulder strap to reduce the risk of injury when operating this unit.

MTD 41ADY90C401 - Using the Cutting Blade - 2

WARNING: Do not use the cutting blade for edging or as an edgeger. Severe personal injury to yourself or others can result.

Before operating the unit with the cutting blade, stand in the operating position. See Figure 25. Refer to Holding the Trimmer.

Cutting Blade Operating Tips

To establish a rhythmic cutting procedure:

Plant feet firmly, comfortably apart.
- Bring the engine to full throttle before entering the material to be cut. At full throttle the blade has maximum cutting power and is less likely to bind, stall or cause blade thrust (which can result in serious personal injury to the operator or others).

MTD 41ADY90C401 - Cutting Blade Operating Tips - 1

WARNING: Blade thrust may occur when the spinning blade contacts an object that it does not immediately cut. Blade thrust can be violent enough to cause the unit and/or operator to be propelled in any direction, and possibly lose control of the unit. Blade thrust can occur without warning if the blade snags, stalls or binds. This is more likely to occur in areas where it is difficult to see the material being cut.

  • Cut while swinging the upper part of your body from left to right.
  • Always release the throttle trigger and allow the engine to return to idle speed when not cutting.
  • When you are finished, always unsnap the unit from the harness before taking off the harness.

MTD 41ADY90C401 - Cutting Blade Operating Tips - 2

WARNING: The blade continues to spin after the engine is turned off. The coasting blade can seriously cut you if accidentally touched.

  • Swing the unit in the opposite direction as the blade spins, which increases the cutting action.
  • After the return swing, move forward to the next area to be cut plant your feet again.
  • The cutting blade is designed with a second cutting edge. You can use it by removing the blade, turning it upside down, and reinstalling it.

MTD 41ADY90C401 - Cutting Blade Operating Tips - 3

WARNING: Do not sharpen the cutting blade. Sharpening the blade can cause the blade tip to break off while in use. This can result in severe personal injury to yourself or others. Replace the blade.

To reduce the chance of material wrapping around the blade, follow these steps:

  • Cut at full throttle
  • Swing the unit into material to be cut from your left to your right, see Figure 26
  • Avoid the material just cut as you make the return swing

MTD 41ADY90C401 - Cutting Blade Operating Tips - 4

WARNING: Do not clear away any cut material with the engine running or blade turning. To avoid serious personal injury, turn off the engine. Allow the blade to stop before removing materials wrapped around the blade shaft.

MTD 41ADY90C401 - Cutting Blade Operating Tips - 5
Figure 25

MTD 41ADY90C401 - Cutting Blade Operating Tips - 6
Figure 26

SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS

Maintenance Schedule

Perform these required maintenance procedures at the frequency stated in the table. These procedures should also be a part of any seasonal tune-up.

NOTE: Some maintenance procedures may require special tools or skills. If you are unsure about these procedures take your unit to any non-road engine repair establishment, individual or authorized service dealer.

MTD 41ADY90C401 - Maintenance Schedule - 1

WARNING: To prevent serious injury, never perform maintenance or repairs with unit running. Always service and repair a cool unit. Disconnect the spark plug wire to ensure that the unit cannot start.

NOTE: Maintenance, replacement, or repair of the emission control devices and system may be performed by any non-road engine repair establishment, individual or authorized service dealer.

In order to assure peak performance of your engine, inspection of the engine exhaust port may be necessary after 50 hours of operation. If you notice lost RPM, poor performance or general lack of acceleration, this service may be required. If you feel your engine is in need of this inspection, refer service to any non-road engine repair establishment, individual or authorized service dealer for repair. DO NOT attempt to perform this process yourself as engine damage may result from contaminants involved in the cleaning process for the port.

FREQUENCYMAINTENANCE REQUIREDREFER TO
Before starting engineFill fuel tank with fresh fuelPage 11
Every 10 hoursClean and re-oil air filterPage 18
Every 25 hoursCheck and clean spark arrestor Check spark plug condition and gapPage 19 Page 20
Every 50 hoursInspect exhaust port and spark arrestor screen for clogging or obstruction to assure maximum performance levelsPage 19

Line Installation

This section covers both SplitLine™ and standard single line installation.

Always use Genuine Factory Parts™ 0.095 in. (2.41 mm) replacement line. Using line other than the specified may make the engine overheat or fail.

MTD 41ADY90C401 - Line Installation - 1

WARNING: Never use metal-reinforced line, wire, chain or rope. These can break off and become dangerous projectiles.

There are two methods to replace the trimming line:

  • Wind the inner reel with new line
    Install a prewound inner reel

Winding the Existing Inner Reel

  1. Hold the outer spool with one hand and unscrew the bump knob counterclockwise. See Figure 27. Inspect the bolt inside the bump knob to make sure it moves freely. Replace the bump knob if damaged.
  2. Remove the inner reel from the outer spool. See Figure 27.
  3. Remove spring from the inner reel. See Figure 27.
  4. Use a clean cloth to wipe the inner reel, spring, shaft, and inner surface of the outer spool. See Figure 28.

MTD 41ADY90C401 - Winding the Existing Inner Reel - 1
Figure 27

MTD 41ADY90C401 - Winding the Existing Inner Reel - 2
Figure 28

SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS

  1. Check the indexing teeth on the inner reel and outer spool for wear. If necessary, remove burrs or replace the reel and spool. See Figure 29.

MTD 41ADY90C401 - SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS - 1
Figure 29

NOTE: SplitLine™ can only be used with the inner reel containing slotted holes. Single line can be used on either type of inner reel. Use Figure 30 to identify the inner reel you have.

MTD 41ADY90C401 - SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS - 2
Figure 30

NOTE: Always use the correct line length when installing trimming line on the unit. The line may not release properly if the line is too long.

Single Line Installation

Go To Step 8 for SplitLineTM Installation

  1. Cut approximately 25 feet (7.6 m) of new trimming line, then loop it into two equal lengths. Insert each end of the line through one of the two holes in the inner reel. Pull the line through the inner reel so that the loop is as small as possible. See Figure 31.

MTD 41ADY90C401 - Single Line Installation - 1
Figure 31

  1. Wind the lines in tight even layers onto the reel. See Figure 32. Wind the line in the direction indicated on the inner reel. Place your index finger between the two lines to stop the lines from overlapping. Do not overlap the ends of the line. Proceed to step 11.

MTD 41ADY90C401 - Single Line Installation - 2
Figure 32

SplitLine™ Installation

  1. Cut approximately 12 feet (3.65 m) of new trimming line. Insert one end of the line through one of the two holes in the inner reel. Pull the line through the inner reel until only about 4 inches is left out. See Figure 33.
  2. Insert the end of the line into the open hole in the inner reel and pull the line tight to make the loop as small as possible. See Figure 33.

MTD 41ADY90C401 - SplitLine™ Installation - 1
Figure 33

  1. Before winding, split the line back about 6 inches.
  2. Wind the line in tight even layers in the direction indicated on the inner reel.

NOTE: Failure to wind the line in the direction indicated will cause the cutting attachment to operate incorrectly.

  1. Insert the ends of the line into the two holding slots. See Figure 34.
  2. Insert the ends of the line through the eyelets in the outer spool and place inner reel with spring inside the outer spool. See Figure 35. Push the inner reel and outer spool together. While holding the inner reel and outer spool, grasp the ends and pull firmly to release the line from the holding slots in the reel.

SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS

MTD 41ADY90C401 - SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS - 1
Figure 34

NOTE: The spring must be assembled on the inner reel before reassembling the cutting attachment.

  1. Hold the inner reel in place and install the bump knob by turning counterclockwise. Tighten securely.

MTD 41ADY90C401 - SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS - 2
Figure 35

Installing a Pre Wound Reel

  1. Hold the outer spool with one hand and unscrew the bump knob clockwise. See Figure 27. Inspect the bolt inside the bump knob to make sure it moves freely. Replace the bump knob if damaged.
  2. Remove the old inner reel from the outer spool. See Figure 27.
  3. Remove the spring from the old inner reel. See Figure 27.
  4. Place the spring in the new inner reel.

NOTE: The spring must be assembled on the inner reel before reassembling the cutting attachment.

  1. Insert the ends of the line through the eyelets in the outer spool. See Figure 35.
  2. Place the new inner reel inside the outer spool. Push the inner reel and outer spool together. While holding the inner reel and outer spool, grasp the ends and pull firmly to release the line from the holding slots in the reel.
  3. Hold the inner reel in place and install the bump knob by turning counterclockwise. Tighten securely.

Replacement Parts

For replacement parts, refer to the Accessories / Replacement Parts section.

Air Filter Maintenance

Removing the Air Filter/Muffler Cover

MTD 41ADY90C401 - Air Filter Maintenance - 1

WARNING: To avoid serious personal injury, always turn your trimmer off and allow it to cool before you clean or service it.

  1. Remove the four (4) screws securing the air filter/ muffler cover. See Figure 36. Use a flat blade or T20 Torx bit screwdriver.
  2. Pull the cover from the engine. Do not force.

MTD 41ADY90C401 - Air Filter Maintenance - 2
Figure 36

Cleaning the Air Filter

MTD 41ADY90C401 - Cleaning the Air Filter - 1

WARNING: To avoid serious personal injury, always turn your trimmer off and allow it to cool before you clean it or perform any maintenance.

Clean and re-oil the air filter every 10 hours of operation. It is an important item to maintain. Failure to maintain the air filter will Void the warranty.

  1. Remove air filter/muffler cover. See Removing the Air Filter/Muffler Cover.
  2. Turn cover over and look inside to locate the air filter. Remove the air filter from inside the air filter/muffler cover. See Figure 37.
  3. Wash the filter in detergent and water. See Figure 38. Rinse the filter thoroughly. Squeeze out excess water. Allow it to dry completely.
  4. Apply enough clean SAE 30 oil to lightly coat the filter. See Figure 39.
  5. Squeeze the filter to spread and remove excess oil. See Figure 40.

SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS

MTD 41ADY90C401 - SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS - 1
Figure 37

MTD 41ADY90C401 - SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS - 2
Figure 39
Figure 38

  1. Replace the air filter inside the air filter/muffler cover. See Figure 37.

NOTE: Operating the unit without the air filter and air filter/muffler cover assembly, will Void the warranty.

Reinstalling the Air Filter/Muffler Cover

  1. Place the air filter/muffler cover over the back of the carburetor and muffler. Align the screw holes.
  2. Insert the four (4) screws into the holes in the air filter/muffler cover and tighten. See Figure 36. Do not over tighten.

Spark Arrestor Maintenance

  1. Remove air filter/muffler cover. See Removing the Air Filter/Muffler Cover.
  2. Locate muffler front and the two (2) bolts securing it to the engine. See Figure 41. Remove the two (2) bolts using a flatblade screwdriver or 5/16-inch socket or nut driver. Pull muffler off of the engine.
  3. Turn muffler over to the back side and locate the exhaust gasket. Remove the muffler gasket from the muffler. See Figure 41.

NOTE: If the exhaust gasket is torn or damaged, replace it with a new gasket before reassembling muffler.
4. Using a small flatblade screwdriver, carefully pry up the spark arrestor from the recessed hole. See Figure 42. Remove the spark arrestor from the muffler.

  1. Clean the spark arrestor with a wire brush. Replace it if it is damaged or if it is impossible to clean thoroughly. See Figure 42.
  2. Reinstall the spark arrester by pressing it into the recessed hole on the muffler's back side. Make sure it fits tightly against the muffler and is not raised up.
  3. Place the exhaust gasket against muffler's back side. Align the gasket bolt holes with the bolt holes in the muffler. While holding exhaust gasket in place, insert the bolts into the muffler's front side. See Figure 41.
  4. Place the muffler (with the exhaust gasket in place and bolts inserted), against the engine, aligning the bolt holes. Tighten the bolts to secure the muffler to the engine. If using a torque wrench torque to: 80-90 in. • lb. (9-10.2 N • m).

MTD 41ADY90C401 - Spark Arrestor Maintenance - 1

WARNING: If the muffler is not tightened securely, it could fall off causing damage to the unit and possible serious personal injury.

  1. Reinstall the air filter/muffler cover.

MTD 41ADY90C401 - Spark Arrestor Maintenance - 2
Figure 41

MTD 41ADY90C401 - Spark Arrestor Maintenance - 3
Figure 42

SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS

Carburetor Adjustment

The idle speed of the engine is adjustable through the air filter/muffler cover. See Figure 43.

NOTE: Careless adjustments can seriously damage your unit. An authorized service dealer should make carburetor adjustments.

Check Fuel Mixture

Old and/or improperly mixed fuel is usually the reason for improper unit performance. Drain and refill the tank with fresh, properly mixed fuel prior to making any adjustments. Refer to Oil and Fuel Information.

Clean Air Filter

The condition of the air filter is important to the operation of the unit. A dirty air filter will restrict air flow and change the air/fuel mixture. This is often mistaken for an out of adjustment carburetor. Check the condition of the air filter before adjusting the idle speed screw. Refer to Air Filter Maintenance.

Adjust Idle Speed

MTD 41ADY90C401 - Adjust Idle Speed - 1

WARNING: The cutting attachment may spin during idle speed adjustments. Wear protective clothing and observe all safety instructions to prevent serious personal injury.

If, after checking the fuel mixture and cleaning the air filter, the engine still will not idle, adjust the idle speed as follows.

  1. Start the engine and let it run at a high idle for a minute to warm up. See Starting/Stopping Instructions.
  2. Release the throttle trigger and let the engine idle. If the engine stops, insert a small Phillips or flat blade screwdriver into the hole in the air filter/muffler cover. See Figure 43. Turn the idle speed screw in, clockwise, 1/8 of a turn at a time (as needed) until the engine idles smoothly.

MTD 41ADY90C401 - Adjust Idle Speed - 2
Figure 43

NOTE: The cutting attachment should not rotate when the engine idles.

  1. If the cutting attachment rotates when the engine idles, turn the idle speed screw counterclockwise 1/8 of a turn at a time (as needed), to reduce idle speed.

Checking the fuel mixture, cleaning the air filter, and adjusting the idle speed should solve most engine problems.

If this is not the case and the following are all true:

  • The engine will not idle
  • The engine hesitates or stalls on acceleration
  • There is a loss of engine power

Have the carburetor adjusted by an authorized service dealer.

MTD 41ADY90C401 - Adjust Idle Speed - 3

WARNING: After turning the unit off, make sure the cutting attachment has stopped before setting the unit down. This helps prevent serious personal injury.

Replacing the Spark Plug

Use a Champion RDJ7Y spark plug (or equivalent). The correct air gap is 0.020 inch (0.5 mm). Remove the plug after every 25 hours of operation and check its condition.

  1. Stop the engine and allow it to cool. Grasp the plug wire firmly and pull it from the spark plug.
  2. Clean around the spark plug. Remove the spark plug from the cylinder head by turning a 5/8 in. socket counterclockwise.
  3. Replace cracked, fouled or dirty spark plug. Set the air gap at 0.020 in. (0.5 mm) using a feeler gauge. See Figure 44.

MTD 41ADY90C401 - Replacing the Spark Plug - 1

CAUTION: Do not sand blast, scrape or clean electrodes. Grit in the engine could damage the cylinder.

  1. Install a correctly-gapped spark plug in the cylinder head. Tighten by turning the 5/8 inch socket clockwise until snug.

If using a torque wrench torque to:

110-120 in. · lb. (12.3-13.5 N·m).

Do not over tighten.

MTD 41ADY90C401 - Replacing the Spark Plug - 2
Figure 44

SECTION 7: MAINTENANCE AND REPAIR INSTRUCTIONS

Cleaning

MTD 41ADY90C401 - Cleaning - 1

WARNING: To avoid serious personal injury, always turn your trimmer off and allow it to cool before you clean or service it.

Use a small brush to clean off the outside of the unit. Do not use strong detergents. Household cleaners that contain aromatic oils such as pine and lemon, and solvents such as kerosene, can damage plastic housing or handle. Wipe off any moisture with a soft cloth.

Storage

  • Never store the unit with fuel in the tank where fumes may reach an open flame or spark.
  • Allow the engine to cool before storing.
  • Store the unit locked up to prevent unauthorized use or damage.
  • Store the unit in a dry, well-ventilated area.
  • Store the unit out of the reach of children.

Long Term Storage

If the unit will be stored for an extended time, use the following storage procedure:

  1. Drain all fuel from the fuel tank into a container with the same 2-cycle fuel mixture. Do not use fuel that has been stored for more than 60 days. Dispose of the old fuel/oil mix in accordance to Federal, State, and Local regulations.
  2. Start the engine and allow it to run until it stalls. This ensures that all fuel has been drained from the carburetor.
  3. Allow the engine to cool. Remove the spark plug and put 1 oz. (30 ml) of any high quality motor oil or 2-cycle oil into the cylinder. Pull the starter rope slowly to distribute the oil. Reinstall the spark plug.

NOTE: Remove the spark plug and drain all of the oil from the cylinder before attempting to start the trimmer after storage.

  1. Thoroughly clean the unit and inspect for any loose or damaged parts. Repair or replace damaged parts and tighten loose screws, nuts or bolts. The unit is ready for storage.

Transporting

  • Allow the engine to cool before transporting.
  • Secure the unit while transporting.
  • Drain fuel from unit.
  • Tighten fuel cap before transporting.

Accessories/Replacement Parts

2-Cycle Oil 147543
Spark Plug 610311
Spark Arrestor 182747
Replacement Line 180120
Replacement Line Cartridge 147345
Inner Reel Spring 610636
Outer Spool 683301
Inner Reel 147495
Bump Knob 180814
Fuel Cap 180000
Shoulder Strap 682075

For specific replacement parts, refer to the parts list located on the inside back cover of this manual.

SECTION 8: TROUBLESHOOTING GUIDE

TroublePossible Cause(s)Corrective Action
ENGINE WILL NOT START• Empty fuel tank • Primer bulb wasn't pressed enough • Engine is flooded • Old or improperly mixed fuel • Fouled spark plug • Plugged spark arrester • EZ-Start lever was not set• Fill fuel tank with properly-mixed fuel • Press primer bulb fully and slowly 10 times • Hold throttle control and pull starter rope until it starts • Drain gas tank and add fresh fuel mixture • Replace or clean spark plug • Clean or replace the spark arrester • Move lever to start
ENGINE WILL NOT IDLE• Air filter is plugged • Old or improperly mixed fuel • Improper carburetor adjustment• Replace or clean the air filter • Drain gas tank and add fresh fuel mixture • Adjust according to the Carburetor Adjustment section
ENGINE WILL NOT ACCELERATE• Old or improperly mixed fuel • Improper carburetor adjustment • Cutting attachment bound with grass • Dirty air filter • Plugged spark arrester• Drain gas tank and add fresh fuel mixture • Take to an authorized service dealer for adjustment • Stop the engine and clean the cutting attachment • Clean or replace the air filter • Clean or replace spark arrester
ENGINE LACKS POWER OR STALLS WHEN CUTTING• Old or improperly mixed fuel • Improper carburetor adjustment • Fouled spark plug • Plugged spark arrester• Drain gas tank and add fresh fuel mixture • Take to an authorized service dealer for adjustment • Replace or clean spark plug • Clean or replace the spark arrester
CUTTING ATTACHMENT WILL NOT ADVANCE LINE• Cutting attachment bound with grass • Cutting attachment out of line • Inner reel bound up • Cutting head is dirty • Line welded • Line twisted when refilled • Not enough line is exposed• Stop the engine and clean cutting attachment • Refill with new line • Replace the inner reel • Clean inner reel and outer spool • Disassemble, remove the welded section and rewind • Disassemble and rewind the line • Push the bump knob and pull out line until 4 inches (102 mm) of line is outside of the cutting attachment
CUTTING LINE ADVANCES WILDLY• Oil is in the cutting head• Clean the cutting head attachment

If further assistance is required, contact your authorized service dealer

SECTION 9: SPECIFICATIONS

Engine*

Engine Type.. Air-Cooled, 2-Cycle
Stroke 1.25 in. (31.75 mm)
Displacement 1.9 cu in. (31 cc)
Clutch Type Centrifugal
Idle Speed RPM 2,800 - 4,400 rpm
Operating RPM 7,200+ rpm
Ignition Type. Electronic
Ignition Switch. Rocker Switch
Spark Plug Gap 0.020 in. (0.5 mm)
Lubrication . Fuel/Oil Mixture
Fuel/Oil Ratio. 40:1
Carburetor Diaphragm, All-Position
Auto Rewind
Muffler Baffled with Guard
Throttle Manual Spring Return
Fuel Tank Capacity. 13 oz. (384 ml)

Drive Shaft and Cutting Attachment*

Drive Shaft Housing Steel Tube, EZ-LinkTM
Throttle Control. Finger-Tip Trigger with Lock-Out
Approximate Unit Weight (No fuel, with cutting attachment, shield and J-handle) 14 lbs. (6.35 kg)
Cutting Mechanism 4-Tooth Cutting Blade, Dual String Cutting Head
Line Spool Bump Line Releaser
Line Spool Diameter 4 inches (101.6 mm)
Trimming Line Diameter 0.095 inch (2.41 mm)
Cutting Path Diameter, Cutting Attachment 18 inches (45.7 cm)
Cutting Path Diameter, Cutting Blade 8 inches (204 mm)
Shoulder Harness Single Quick-Snap

*All specifications are based on the latest product information available at the time of printing. We reserve the right to make changes at any time without notice.

EPA Emission Control Warranty Statement

Your Warranty Rights and Obligations

The Environmental Protection Agency and MTD LLC (MTD) are pleased to explain the emission control system warranty on your 2002 and later small off-road engine. New small off-road engines must be designed, built and equipped to meet stringent anti-smog standards. Yard Man must warrant the emission control system on your small off-road engine for the periods of time listed below provided there has been no abuse, neglect or improper maintenance of your small off-road engine.

Your emission control system may include parts such as the carburetor or fuel-injected system, the ignition system, and catalytic converter. Also included may be hoses, belts, connectors and other emission-related assemblies.

Where a warrantable condition exists, Yard Man will repair your small off-road engine at no cost to you including diagnosis, parts and labor.

The 2002 and later small off-road engines are warranted for two years. If any emission-related part on your engine is defective, the part will be repaired or replaced my Yard Man.

Owners Warranty Responsibilities

  • As the small off-road engine owner, you are responsible for the performance of the required maintenance listed in your operator's manual. Yard Man recommends that you retain all receipts covering maintenance on your small off-road engine, but Yard Man cannot deny warranty solely for the lack of receipts or for your failure to ensure the performance of all scheduled maintenance.
  • As the small off-road engine owner, you however should be aware that Yard Man may deny you warranty coverage if your small off-road engine or a part has failed due to abuse, neglect, improper maintenance or unapproved modifications.
  • You are responsible for presenting your small off-road engine to a Yard Man Authorized Service Center as soon as a problem exists. The warranty repairs should be completed in a reasonable amount of time, not to exceed 30 days.

If you have any questions regarding your warranty rights and responsibilities, you should call 1-800-345-8746.

Manufacturer's Warranty Coverage

  • The warranty period begins on the date the engine or equipment is delivered to the retail purchaser.
  • The manufacturer warrants to the initial owner and each subsequent purchaser, that the engine is free from defects in material and workmanship which cause the failure of a warranted part for a period of two years.
  • Repair or replacement of warranted part will be performed at no charge to the owner at an Authorized Yard Man Service Center. For the nearest location please contact Yard Man at: 1-800-345-8746.
  • Any warranted part which is not scheduled for replacement, as required maintenance or which is scheduled for only for regular inspection to the effect of "Repair or Replace as Necessary" is warranted for the warranty period. Any warranted part which is scheduled for replacement as required maintenance will be warranted for the period of time up to the first scheduled replacement point for that part.
  • The owner will not be charged for diagnostic labor which leads to the determination that a warranted part is defective, if the diagnostic work is performed at an Authorized Yard Man Service Center.
  • The manufacturer is liable for damages to other engine components caused by the failure of a warranted part still under warranty.
  • Failures caused by abuse, neglect or improper maintenance are not covered under warranty.
  • The use of add-on or modified parts can be grounds for disallowing a warranty claim. The manufacturer is not liable to cover failures of warranted parts caused by the use of add-on or modified parts.
  • In order to file a claim, go to your nearest Authorized Yard Man Service Center. Warranty services or repairs will be provided at all Authorized Yard Man Service Centers.
  • Any manufacturer approved replacement part may be used in the performance of any warranty maintenance or repair of emission related parts and will be provided without charge to the owner. Any replacement part that is equivalent in performance or durability may be used in non-warranty maintenance or repair and will not reduce the warranty obligations of the manufacturer
  • The following components are included in the emission related warranty of the engine, air filter, carburetor, primer, fuel lines, fuel pick up/ fuel filter, ignition module, spark plug and muffler.

MANUFACTURER'S LIMITED WARRANTY FOR:

YaRD-Man)by MTD

The limited warranty set forth below is given by MTD LLC ("MTD") with respect to new merchandise purchased and used in the United States, its possessions and territories.

MTD warrants this product against defects in material and workmanship for a period of two (2) years commencing on the date of original purchase and will, at its option, repair or replace, free of charge, any part found to be defective in material or workmanship. This limited warranty shall only apply if this product has been operated and maintained in accordance with the Operator's Manual furnished with the product, and has not been subject to misuse, abuse, commercial use, neglect, accident, improper maintenance, alteration, vandalism, theft, fire, water or damage because of other peril or natural disaster. Damage resulting from the installation or use of any accessory or attachment not approved by MTD for use with the product(s) covered by this manual will void your warranty as to any resulting damage. This warranty is limited to ninety (90) days from the date of original retail purchase for any MTD product that is used for rental or commercial purposes, or any other income-producing purpose.

HOW TO OBTAIN SERVICE: Warranty service is available, WITH PROOF OF PURCHASE THROUGH YOUR LOCAL AUTHORIZED SERVICE DEALER. To locate the dealer in your area, please check for a listing in the Yellow Pages or contact the Customer Service Department of MTD LLC by calling 1-800-345-8746 or writing to P.O. Box 361131, Cleveland OH 44136-0019 or if in Canada call 1-800-668-1238. No product returned directly to the factory will be accepted unless prior written permission has been extended by the Customer Service Department of MTD LLC.

This limited warranty does not provide coverage in the following cases:

A. Tune-ups - Spark Plugs, Carburetor Adjustments, Filters.
B. Wear items - Bump Knobs, Outer Spools, Cutting Line, Inner Reels, Starter Pulley, Starter Ropes, Drive Belts.
C. MTD does not extend any warranty for products sold or exported outside of the United States of America, its possessions and territories, except those sold through MTD's authorized channels of export distribution.

MTD reserves the right to change or improve the design of any MTD Product without assuming any obligation to modify any product previously manufactured.

No implied warranty, including any implied warranty of merchantability or fitness for a particular purpose, applies after the applicable period of express written warranty above as to the parts as identified. No other express warranty or guaranty, whether written or oral, except as mentioned above, given by any person or entity, including a dealer or retailer, with respect to any product shall bind MTD. During the period of the Warranty, the exclusive remedy is repair or replacement of the product as set forth above. (Some states do not allow limitations on how long an implied warranty lasts, so the above limitation may not apply to you.)

The provisions as set forth in this Warranty provide the sole and exclusive remedy arising from the sales. MTD shall not be liable for incidental or consequential loss or damages including, without limitation, expenses incurred for substitute or replacement lawn care services, for transportation or for related expenses, or for rental expenses to temporarily replace a warranted product. (Some states do not allow limitations on how long an implied warranty lasts, so the above limitation may not apply to you.)

In no event shall recovery of any kind be greater than the amount of the purchase price of the product sold. Alteration of the safety features of the product shall void this Warranty. You assume the risk and liability for loss, damage, or injury to you and your property and/or to others and their property arising out of the use or misuse or inability to use the product.

This limited warranty shall not extend to anyone other than the original purchaser, original lessee or the person for whom it was purchased as a gift.

How State Law Relates to this Warranty: This warranty gives you specific legal rights, and you may also have other rights which vary from state to state.

To locate your nearest service dealer dial 1-800-345-8746 in the United States or 1-800-668-1238 in Canada.

MTD LLC

P.O. Box 361131

Cleveland, OH 44136-0019

For A Growing World.

MTD 41ADY90C401 - YaRD-Man)by MTD - 1

TABLE DES MATIÈRES

Contenu Page

Starting Instructions

INSTRUCTIONS D'ARRÉT

SECTION 6: MODE D'EMPLO

FONCTIONNEMENT DU EZ-LinkMC

SECTION 6: MODE D'EMPLO

TENUE DE LA DÉSHERBEUSE

MTD 41ADY90C401 - TENUE DE LA DÉSHERBEUSE - 1

SECTION 6: MODE D'EMPLO

COUPE DÉCORATIVE

Air Cleaner/Muffler Cover Assembly (includes 2 & 41)

Air Cleaner Filter

Carburetor Mounting Screw Assembly

Choke Extension

Choke Plate

Carburetor Assembly (includes 7 & 18)

Carburetor Gasket

Carb Mount Screw

Primer and Hose Assembly

Carb Mount Assembly (includes 8 & 11)

Reed Assembly

Carburetor Mount Gasket

Crank Case Service Assembly (includes 10)

Rear Mounting Pad

Fuel Tank Assembly (includes 16-18)

Fuel Cap Assembly

Fuel Return Line

Fuel Line Assembly

Front Mounting Pad

Shroud Extension and Stand

Flywheel Assembly

Spacer

Recoil Pulley Assembly

Recoil Spring

Rope Guide

Pulley Retainer

Pull Handle

Rope

Pressure Plate Assembly

Plate Screw

Item Part No.

31 753-04335

32 791-181862

33 791-182368

34 791-182369

35 791-153592

36 753-1204

37 791-181345

38 791-182519

39 753-04003

40 791-180217

41 791-182798

42 791-611063

43 753-04337

44 791-610311B

45 791-182066

46 791-182747

47 753-04159

48 791-147575

49 753-04323

50 753-1207

51 753-1197

52 791-182723

  • 791-180090

  • 791-180091

  • 753-1209

  • 753-04334

  • 791-181599

  • 753-04134

  • Items Not Shown

Description

Starter Housing Assembly

(includes 23-30 & 32)

Housing Screw

Clutch Washer

Clutch Rotor Assembly

Clutch Drum Assembly

Clutch Cover Assembly

(includes 41-44)

Cover Screw

Anti-Rotation Screw

Clamping Screw

Clamping Nut

Wire Leads and Sleeve

Ground Tab

Module Assembly

Spark Plug

Muffler Assembly (includes 47-49)

Spark Arrestor Screen

Exhaust Gasket

Muffler Mounting Bolt Assembly

Cylinder Assembly (includes 52)

Piston and Rod Assembly

Cylinder Gasket

Cylinder Bolt

O.E.M. Carburetor Repair Kit (Zama)

Gasket Diaphragm Repair Kit (Zama)

Piston Ring Set

Short Block Assembly

(includes 8, 12, 14, 22, 48, 51-56)

Clutch Springs (Qty. 2)

Eng Gasket Kit

Item Part No.

1 753-04339
2 753-04340
3 791-00058
4 791-182690
5 791-182405
6 753-04278
7 791-610327
8 753-04236
9 791-181099
10 791-612831
791-612021
12 791-683295
791-181811
791-181812
15 791-181813
16 791-181814
791-181815
791-145569
19 791-182928
20 791-182057
21 791-181617
22 791-181618
23 791-181886
24 791-180804
25 791-613300
26 791-182200
791-182193
28 791-182195
29 791-145569
80 791-182196
31 791-147492
32 791-683304
33 753-1191
84 791-682061
85 791-147490
86 791-612483
37 791-683301
88 791-612026
89 791-610636B
40 791-147495
791-180814B
42 791-145873B
43 791-181699
791-180014B
791-613226
* 791-682075B

Description

Throttle Housing and Trigger

Assembly (includes 2-4)

Throttle Trigger Lock-Out

Throttle Trigger

Throttle Trigger Spring

Switch Assembly

Throttle Cable Assembly

Harness Clip

Upper Drive Shaft Housing Assembly

J-Handle Assembly (includes 10 & 11)

Grip

Tube Closure

Handle Bracket Assembly (includes 13-18)

Screw

Upper Handle Clamp

Middle Handle Clamp

Lower Handle Clamp

Nut

Anti-Rotation Screw

Click-Link Coupler (includes 20-23)

Screw

Bolt

Adjustment Knob

Knob Retaining Nut

Lower Drive Shaft Housing Assembly

Lower Flexible Drive Shaft

Shield Mount Screw Assembly

2 piece Gearbox Assembly (includes 28-30)

Gearbox Mounting Hardware

Anti-Rotation Screw

Blade Driver

Blade Shield/Shield Mount

Shield Mounting Screw

Shield and Blade Assembly (includes 34)

Blade Assembly

Retaining Washer

Spool Shaft

Outer Spool and Eyelet Assembly

Retainer

Spring

Inner Reel

Bump Head Knob Assembly

4-Tooth Blade

Nut

Blade Retaining Kit (includes 35 & 43)

Locking Rod Tool

Shoulder Harness

2 Piece Gearbox Assembly Parts - Item 27

44 791-182191

45 791-182192

46 791-182194

47 791-182199

48 791-182198

49 791-182197

50 753-04348

Left Housing

Right Housing

Pinion Gear Assembly

Output Shaft Bushing

Output Shaft Gear

Output Shaft Assembly

(includes 46 & 47)

Palnut

Optional Accessories

  • 753-1160

  • 753-1161

  • 791-682075B

  • Items Not Shown

Reel and Line Assembly

Bump Head Assembly

(includes 36-41)

Shoulder Harness

MTD 41ADY90C401 - Optional Accessories - 1

MTD 41ADY90C401 - Optional Accessories - 2

GARANTÍA LIMITADA DEL FABRICANTE PARA:

YaRD-Man) by MTD

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Product information

Brand : MTD

Model : 41ADY90C401

Category : Brush cutter