Cub Cadet ST426s Operator's Manual

Operator’s Manual

4-Cycle Trimmer

ST426s

769-07001 P00 03/11

TABLE OF CONTENTS

Service Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Rules for Safe Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Know Your Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Assembly Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Oil and Fuel Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Starting/Stopping Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Maintenance and Repair Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Cleaning and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Optional Accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Troubleshooting Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

All information, illustrations, and specifications in this manual 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.

2011

SAVE THESE INSTRUCTIONS

For service call 1-877-282-8684, or 1-800-668-1238 in Canada to obtain a list of authorized service dealers near you. For more details about your unit, visit our website at www.cubcadet.com or www.cubcadet.ca.

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.

DO NOT RETURN THE UNIT TO THE RETAILER. PROOF OF PURCHASE WILL BE REQUIRED FOR WARRANTY SERVICE.

Service on this unit both within and after the warranty period should be performed only by an authorized and approved service dealer.

SPARK ARRESTOR NOTE 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 arrestor, 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 arrestor. If it requires replacement, ask your LOCAL SERVICE DEALER to install the Accessory Part #753-06334 Muffler Assembly.

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 1-877-282-8684 IN U.S. OR 1-800-668-1238 in CANADA

READ ALL INSTRUCTIONS 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 and teens under the age of 15 must not use the unit, except for teens supervised by an adult.

• All guards and safety attachments must be installed properly before operating the unit.

• Inspect the unit before use. Replace damaged parts. Make sure all fasteners are in place and secure. Replace parts that are cracked, chipped, or damaged in any way. Do not operate the unit with loose or damaged parts.

• Carefully inspect the area before starting the unit. Remove all debris and hard or sharp objects such as glass, wire, etc.

• Clear the area of children, bystanders, and pets. At a minimum, keep all children, bystanders, and pets outside a 50 feet (15 m) radius; there still may be a risk to bystanders from thrown objects. Bystanders should be encouraged to wear eye protection. If you are approached, stop the unit immediately.

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

• Squeeze the throttle control and check that it returns automatically to the idle position. Make all adjustments or repairs before using unit.

SAFETY WARNINGS FOR GAS UNITS

• 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. Always loosen the fuel tank cap slowly to relieve any pressure in the tank before fueling. Do not smoke.

• Always add fuel in a clean, well-ventilated outdoor area where there are no sparks or flames. Do not smoke.

• Never operate the unit without the fuel cap securely in place.

• Avoid creating a source of ignition for spilled fuel. Wipe up any spilled fuel from the unit immediately before starting the engine. Move the unit at least 30 feet (9.1 m) from the fueling source and site before starting the engine. Do not smoke.

• Never start or run the unit inside a closed room or building. Breathing exhaust fumes can kill. Only operate this unit in a well-ventilated outdoor area.

WHILE OPERATING

• Be aware of the risk of injury to the head, hands and feet.

• Wear safety glasses or goggles that are marked as meeting ANSI Z87.11989 standards. Also wear ear/hearing protection when operating this unit. Wear a face or dust mask if the operation is dusty.

• Wear long sleeve shirt, heavy long pants, boots and gloves. 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 D-handle to your size 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. Be in the starting position whenever pulling the starter rope. The operator and unit must be in a stable position while starting. See Starting/Stopping Instructions.

• Use the right tool. Only use this tool for the purpose intended.

• Do not overreach. Always keep proper footing and balance.

• Always hold the unit with both hands when operating. Keep a firm grip on both the front and rear handle 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 is rotating.

• Do not touch the engine or muffler. These parts get extremely hot from operation. They remain hot for a short time after you turn off the unit.

• Do not operate the engine faster than the speed needed to cut, trim or edge. Do not run the engine at high speed when you are 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.

• Stop and switch the engine to off for maintenance, repair, or for changing the cutting attachment or other attachments.

• Use only original equipment manufacturer 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, or damage to the unit, and void your warranty.

• Keep unit clean of vegetation and other materials. They may become lodged between the cutting attachment and shield.

• To reduce fire hazard, replace faulty muffler and spark arrestor, keep the engine and muffler free from grass, leaves or other debri.

• IMPORTANT SAFETY INSTRUCTIONS •

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.

SYMBOL MEANING

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

or maintenance of the equipment.

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.

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.

WARNING:

When using the unit, you must follow the safety rules. Please read these instructions before operating the unit in order to ensure the safety of the operator and any bystanders. Please keep these instructions for later use.

SAFETY ALERT:

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.

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.

WARNING:

Gasoline is highly flammable, and its vapors can

explode if ignited. Take the following precautions:

RULES FOR SAFE OPERATION

CALIFORNIA PROPOSITION 65 WARNING:

Engine exhaust, some of its constituents and certain finished components contain or emit chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. Wash hands after handling.

RULES FOR SAFE OPERATION

• SAFETY AND 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.

OTHER SAFETY WARNINGS

• Never store the unit, with fuel in the tank, inside a building where fumes may reach an open flame or spark.

• Always 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. Keep 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 the 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

SYMBOL MEANING

• SAFETY ALERT SYMBOL

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

• READ OPERATOR'S MANUAL

WARNING: 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.

• WEAR EYE AND HEARING PROTECTION

WARNING: Thrown objects and loud noise can cause

severe eye injury and hearing loss. Wear eye protection meeting ANSI Z87.1-1989 standards and ear protection when operating this unit. Use a full face shield when needed.

• UNLEADED FUEL

Always use clean, fresh unleaded fuel

• ON/OFF STOP CONTROL

ON / START / RUN

• ON/OFF STOP CONTROL

OFF or STOP

• DO NOT USE E85 FUEL IN THIS UNIT

WARNING: It has been proven that fuel containing greater

than 10% ethanol will likely damage this engine and void the warranty.

• THROWN OBJECTS AND ROTATING CUTTER CAN CAUSE SEVERE INJURY

WARNING: Small objects can be propelled at high speed,

causing injury. Keep away from the rotating rotor.

• KEEP BYSTANDERS AWAY

WARNING: Keep all bystanders, especially children and

pets, at least 50 feet (15 m) from the operating area.

• HOT SURFACE WARNING

Do not touch a hot muffler or cylinder. You may get burned. These parts get extremely hot from operation. When turned off they remain hot for a short time.

• OIL

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

• CHOKE CONTROL

1. • FULL choke position

2. • PARTIAL choke position

3. • RUN choke position

• SHARP BLADE

WARNING: Sharp blade on cutting attachment shield. To

prevent serious injury, do not touch the line cutting blade.

KNOW YOUR UNIT ASSEMBLY INSTRUCTIONS

ADJUSTING THE D-HANDLE

1. Loosen the bolt on the handle just enough to move it (Fig. 1).

2. While holding the unit in the operating position (Fig. 16), move the D-handle to the location that provides the best grip.

3. Tighten the bolt until the D-handle is secure. (Fig. 1)

INSTALL THE CUTTING HEAD SHIELD

1. Place the cutting head shield onto the guard mount bracket, making sure to align the holes on the shield with the ones in the guard mount bracket. (Fig. 2)

2. Take the 4 shield screws and screw each one into the shield until finger tight.

3. Using a Phillips screwdriver, tighten the screws until the shield is firmly in place.

INSTALL THE SHOULDER SUPPORT

1. Put the shoulder support on using the clip. (Fig. 3).

2. Adjust by lifting slightly on the rear of the lower clip then push or pull the loose end of the strap length to fit the operator’s size and comfort. (Fig. 4).

3. Attach the shoulder clip to the unit. (Fig. 5)

Cutting Head Shield

Fuel Cap

Throttle Control

D-Handle

Cutting Head

Shaft Grip

Primer

Bulb

Choke Lever

Spark Plug

On/Off Stop Control

Shaft Housing

Starter

Rope

Grip

Line Cutting Blade

Muffler

Air Filter

Cover

APPLICATIONS

As a trimmer:

• Cutting grass and light weeds.

• Edging

• Decorative trimming around trees, fences, etc.

Rapid-Link™

Fig. 2

Guard Mount

Bracket

Screw (4)

Cutting

Head

Shield

D-Handle

Bolt

Fig. 1

6 in.

(15.24 cm)

Minimum

Throttle Lock-out

Shoulder Strap Clip

TOOLS REQUIRED:

• Phillips screwdriver

• 3/8” socket

Fig. 3

Fig. 4

Adjustment

Ta b

Support

Clip

Fig. 5

Support

Fitting

FUELING THE UNIT

1. Remove the fuel cap (Fig. 9).

2. Place the gas container’s spout into the fill hole on the fuel tank (Fig. 9) and fill the tank.

NOTE: Do not overfill the tank.

3. Wipe up any gasoline that may have spilled.

4. Reinstall the fuel cap.

5. Move the unit at least 30 ft. (9.1 m) from the fueling source and site before starting the engine.

NOTE: Dispose of the old gasoline in accordance with federal, state and

local regulations.

OIL AND FUEL INFORMATION

RECOMMENDED OIL TYPE

Using the proper type and weight of oil in the crankcase is extremely important. Check the oil before each use and change the oil regularly. Failure to use the correct oil, or using dirty oil, can cause premature engine wear and failure.

Use a high-quality SAE 30 weight oil of API (American Petroleum Institute) service class SF, SG, SH.

ADDING OIL TO CRANKCASE: INITIAL USE NOTE: This unit is shipped without oil. In

order to avoid damage to the unit, put oil in the crankcase before you attempt to start the unit.

Your unit is supplied with one 2.2 fl.oz. (60 ml) bottle of SAE 30 SF, SG, SH oil (Fig. 6).

NOTE: Save the bottle of oil. It can be used to

measure the correct amount during future oil changes. See Changing the Oil.

1. Unscrew the top of the bottle of oil and remove the paper seal covering the opening. Replace the top. Next, cut the tip off the funnel spout (Fig. 6).

2. Place unit on a flat, level surface.

3. Remove the oil fill plug from the crankcase (Fig. 8).

4. Pour the entire bottle of oil into the oil fill hole (Fig. 7).

NOTE: Never add oil to the fuel or fuel tank.

5. Wipe up any oil that may have spilled and reinstall the oil fill plug.

Check oil before each use and change as needed. Refer to Checking the Oil Level.

RECOMMENDED FUEL TYPE

Old fuel is the primary reason for improper unit performance. Be sure to use fresh, clean, unleaded gasoline.

NOTE: This is a four cycle engine. In order to avoid damage to the unit, do

not mix oil with gasoline.

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 or form acids when stored. Use fresh fuel (less than 30 days old), when using alcohol-blended fuel.

Using Blended Fuels

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

• Always use fresh unleaded gasoline

• Use the fuel additive STA-BIL® or an equivalent

• Drain tank and run the engine dry before storing unit

Using Fuel Additives

The use of fuel additives, such as STA-BIL® Gas Stabilizer or an equivalent, will inhibit corrosion and minimize the formation of gum deposits. Using a fuel additive can keep fuel from forming harmful deposits in the carburetor for up to six (6) months. 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 gas tank.

WARNING: OVERFILLING OIL CRANKCASE MAY CAUSE

SERIOUS PERSONAL INJURY. Check and maintain the proper oil level in the crank case; it is important and cannot be overemphasized. Check the oil before each use and change it as needed. See Changing the Oil.

WARNING: Add fuel in a clean, well ventilated outdoor area. Wipe

up any spilled fuel immediately. Avoid creating a source of ignition for spilt fuel. Do not start the engine until fuel vapors dissipate.

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.

WARNING: Remove fuel cap slowly to avoid injury from fuel

spray. Never operate the unit without the fuel cap securely in place.

Funnel

Spout

Fig. 6

Oil Fill

Plug

Fig. 8

O-Ring

Fill

Level

Gas Can Spout

Fig. 9

Fuel Cap

Fuel Tank

Fig. 7

Oil Fill Hole

WARNING: DO NOT USE E85 FUEL IN THIS UNIT. It has

been proven that fuel containing greater than 10% ethanol will likely damage this engine and void the warranty.

STARTING/STOPPING INSTRUCTIONS

STARTING INSTRUCTIONS

1. Check the oil level in the crankcase. Refer to Checking the Oil Level.

2. Fill the fuel tank with fresh, clean unleaded gasoline. Refer to Fueling the Unit.

NOTE: There is no need to turn the unit on.

The On/Off Control is in the ON ( I ) position at all times (Fig. 10).

3. Fully press and release the primer bulb 10 times, slowly. Some amount of fuel should be visible in the primer bulb (Fig. 11). If fuel cannot be seen in the bulb, press and release the bulb until fuel is visible.

4. Place the choke lever in Position 1 (Fig. 11).

5. Crouch in the starting position (Fig. 12). Press the throttle lockout in and squeeze the throttle control lever. Pull the starter rope 5 times.

6. Place the choke lever in Position 2 (Fig. 11).

7. While pressing the throttle lockout in and squeezing the throttle control , pull the starter rope 3 to 5 times to start the engine.

8. Keep the throttle squeezed and allow the engine to warm up for 30 to 60 seconds.

9. While continuing to squeeze the throttle control, place the choke lever in Position 3 (Fig. 11) and warm for an additional 60 seconds. The unit may be used during this time.

NOTE: Unit is properly warmed up when

engine accelerates without hesitation.

IF... the engine hesitates, return the choke lever to Position 2 (Fig. 11)

and continue warm-up.

IF... the engine does not start, go back to step 3. IF... the engine fails to start after a few attempts, place the choke lever

in Position 3 and squeeze the throttle control. Pull starter rope until unit starts.

IF WARM... If the engine is already warm, go back to step 6. STOPPING INSTRUCTIONS

1. Release the throttle control and allow the engine to cool down by idling.

2. Press and hold the On/Off Control switch in the OFF (O) position until the unit comes to a complete stop (Fig. 10).

WARNING: Operate this unit only in a well-ventilated outdoor area.

Carbon monoxide exhaust fumes can be lethal in a confined area.

WARNING: Avoid accidental starting. Make sure you are in the

starting position when pulling the starter rope (Fig. 12). To avoid serious injury, the operator and unit must be in a stable position while starting.

Throttle Control

Fig. 10

Starter

Rope

Fig. 12

Throttle Control

Start / On (I)

Stop / Off (O)

Throttle Lockout

Fig. 11

Primer Bulb

Choke Lever

HOW TO START THE UNIT USING THE ELECTRIC STARTER OR POWER START BIT ACCESSORY.

NOTE- This Unit Can Use an Electric Start or Power Start Bit™

Optional Accessory!

Please refer to the Electric Starter or Power Start Bit operator’s manual for proper use of this feature. (Items Sold Separately! Please refer to page 10 of this manual about purchasing these accessories.)

STARTING INSTRUCTIONS

1. Check the oil level in the crankcase. Refer to Checking the Oil Level.

2. Fill the fuel tank with fresh, clean unleaded gasoline. Refer to Fueling the Unit.

NOTE: There is no need to turn the unit on. The On/Off Control is in the

ON ( I ) position at all times (Fig. 10).

4. Move the choke lever to Position 1 (Fig. 11).

5. Crouch in the starting position (Fig. 12). Place the electric starter or power start bit into the back of the unit. Refer to the Operation section of the Electric Starter or Power Start Bit operator’s manual.

6. Press the throttle lockout in and squeeze the throttle control lever. Press and hold the electric starter or drill ON (I) button for 2 seconds.

7. Move the choke lever to Position 2 (Fig. 11).

8. Squeeze the throttle control lever, press and hold the electric starter or drill ON (I) button for 2-second intervals until the unit starts.

9. Continue to squeeze the throttle control, remove the electric starter or drill from the unit and allow the engine to warm up for 30 to 60 seconds.

10. Continue squeezing the throttle control, move the choke lever to Position 3 (Fig. 11) and run the unit for an additional 60 seconds. The unit may be used during this time.

NOTE: Unit is properly warmed up when engine accelerates without

hesitation.

IF... the engine hesitates, return the choke lever to Position 2 (Fig. 11)

and continue warm-up.

IF... the engine does not start, go back to step 3. IF... the engine fails to start after a few attempts, place the choke lever

in Position 3 and squeeze the throttle control. Press and hold the electric starter or drill ON (I) button for 2-second intervals until the unit starts.

IF WARM... If the engine is already warm, go back to step 7. STOPPING INSTRUCTIONS

1. Release the throttle control and allow the engine to cool down by idling.

2. Press and hold the On/Off Control switch in the OFF (O) position until the unit comes to a complete stop (Fig. 10).

IF USING THE OPTIONAL ELECTRIC STARTER OR POWER START

BIT™ ACCESSORY

ADJUSTING TRIMMING LINE LENGTH

The cutting head allows you to release trimming line without stopping the engine. To release more line, lightly tap the cutting attachment on the ground (Fig. 17) while operating the trimmer at high speed.

NOTE: Always keep the trimming line fully

extended. Line release becomes more difficult as the cutting line becomes shorter.

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

For best results, tap the cutting head on bare ground or hard soil. If line release is attempted in tall grass, the engine may stall. Always keep the trimming line fully extended. Line release becomes more difficult as the cutting line becomes shorter.

NOTE: Do not rest the cutting head on the ground while the unit is running. Some line breakage will occur from:

• Entanglement with foreign matter

• Normal line fatigue

• Attempting 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) by working from top to bottom in small increments to avoid premature line wear or engine drag.

• Slowly move the trimmer into and out of the cutting area at the desired height. Move either in a forward-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:

• Proper adherence of explained trimming techniques

• What vegetation is 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.

DECORATIVE TRIMMING

Decorative trimming is accomplished by removing all vegetation around trees, posts, fences and more.

Rotate the whole unit so that the cutting attachment is at a 30° angle to the ground (Fig. 18).

OPERATING INSTRUCTIONS

OPERATING THE RAPID-LINK™ SYSTEM

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

Trimmer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AF720

Hedge Trimmer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AH720

Brushcutter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BC720*

Cultivator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GC720

Edger. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LE720

Pole Saw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PS720

Straight Shaft Trimmer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SS725

Turbo Blower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TB720

*Do NOT use this attachment with an electric powered unit. Removing the Cutting Attachment or Add-On

1. Turn the knob counterclockwise to loosen (Fig. 15).

2. Press and hold the release button (Fig. 13).

3. While firmly holding the upper shaft housing, pull the cutting attachment or add-on straight out of the Rapid-Link™ coupler (Fig. 14).

Installing the Cutting Attachment or Add-On

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 (Fig. 15).

2. While firmly holding the add-on, push it straight into the Rapid-Link™ coupler (Fig. 14).

NOTE: Aligning the release button with the

guide recess will help installation (Fig. 13).

3. Turn the knob clockwise to tighten (Fig. 15).

For edging (when using the line head cutting attachment with Rapid-Link™ models), lock the release button of the cutting attachment into the 90° edging hole (Fig. 15).

HOLDING THE TRIMMER

Before operating the unit, stand in the operating position (Fig. 16). 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 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

WARNING: Before you begin using any attachment, read and

understand the manual that came with the attachment. Follow all safety information contained within.

WARNING: To avoid serious

personal injury and damage to the unit, shut the unit off before removing or installing add-ons.

CAUTION: Lock the release button in the primary hole and

securely tighten the knob before operating this unit.

CAUTION: Add-ons are to be

used in the primary hole only. Using the wrong hole could lead to personal injury or damage to the unit.

Guide Recess

Fig. 13

Release

Button

Rapid-Link™

Coupler

Upper Shaft

Housing

Fig. 14

Lower Shaft

Housing

Primary Hole

Knob

Fig. 15

90˚ Edging Hole

(Trimmer Only)

WARNING: Always wear eye,

hearing, foot and body protection to reduce the risk of injury when operating this unit.

Fig. 16

Fig. 17

Fig. 18

MAINTENANCE AND REPAIR INSTRUCTIONS

4. Remove the oil fill plug.

5. Check the oil level. Oil should be just to the bottom of the threads of the oil fill hole. (Fig. 24).

6. If the level is low, add a small amount of oil to the oil fill hole and recheck (Fig. 24). Repeat this procedure until the oil level reaches the bottom of the threads in the oil fill hole.

NOTE: Do not overfill the unit. NOTE: Make sure the O-ring is in place on the

oil fill plug when checking and changing the oil (Fig. 23).

CHANGING THE OIL

Change the oil while the engine is still warm. The oil will flow freely and carry away more impurities.

1. Remove the oil fill plug.

2. Pour the oil out of the oil fill hole and into a container by tipping the unit to the side (Fig.

25). Allow ample time for complete drainage.

3. Wipe up any oil residue on the unit and clean up any oil that may have spilled. Dispose of the oil according to federal, state and local regulations.

4. Refill the crankcase with 2.2 fl.oz. (60 ml) of SAE 30 SF, SG, SH oil.

NOTE: Use the bottle and spout saved from initial use to measure the

correct amount of oil. The top of the label on the bottle measures approximately 3.4 ounces (100 ml) (Fig. 26). Check the level (Fig.

24). If the level is low, add a small amount of oil and recheck. Do not overfill (Fig. 24).

5. Replace the oil fill plug.

AIR FILTER MAINTENANCE

Cleaning the Air Filter

Failure to maintain the air filter properly can result in poor performance or can cause permanent damage to the engine.

1. Open the air filter cover by pressing the lock tab in and pulling out on the air filter cover (Fig. 27 & 25).

2. Remove the air filter (Fig. 29).

3. Wash the filter in detergent and water. Rinse the filter thoroughly and allow it to dry.

4. Apply enough clean SAE 30 motor oil to lightly coat the filter.

5. Squeeze the filter to spread and remove excess oil.

6. Replace the air filter into the base plate (Fig. 29).

NOTE: If the unit is operated without the air

filter, you will VOID the warranty.

7. Reinstall the air filter cover. Position the two small tabs on the air filter cover into the two slots in the back plate and press the air filter cover down, making sure to align the lock tab with the lock tab slot, until it snaps into place (Fig. 28 & 27).

IDLE SPEED ADJUSTMENT

The idle speed of the engine is adjustable. An idle adjustment screw is between the air filter cover and the engine starter housing (Fig. 30).

CAUTION: Wear gloves to prevent

injury when handling the unit.

WARNING: To avoid serious

personal injury, always turn the unit off and allow it to cool before you clean or service it.

Oil Fill Hole

Fig. 24

Fig. 25

Fill

Level

Fig. 26

Add 1.4-1.5

Oz.

(41-44 ml)

Air Filter

Cover Tab

Fig. 27

Air Filter Cover

Air Filter

Fig. 29

Air Filter

Cover

Fig. 28

Back Plate

Idle

Adjustment

Screw

Fig. 30

Back Plate

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.

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.

NOTE: Please read the California/EPA statement that came with the unit

for a complete listing of terms and coverage for the emissions control devices, such as the spark arrestor, muffler, carburetor, etc.

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.

REMOVING THE LINE

1. Rotate the bump knob clockwise until all line is inside the cutting head (Fig. 19).

2. Using a flat-head screwdriver, insert the tip into the line dimple and just under the exposed portion of the line (Fig. 20)

3. Pull the line straight out until all line is removed from the cutting head.

LINE INSTALLATION

Always use original equipment manufacturer

0.095 in. (2.41 mm) replacement line.

1. Align the arrows on the bump knob with the spool cover eyelets, if they are not already (Fig. 21).

2. Using 10 ft. (3 m) of 0.095 in. (2.41 mm) replacement line push both ends of the line through the holes in the bump knob until they protrude through the eyelets on both sides of the cutting head. Continue pulling the line until approximately 5 ft. (1.5 m) is visible from both sides of the cutting head. (Fig. 22)

3. Hold the spool cover, turn the bump knob clockwise to wind the line around the spool until about 5 in. (12.7 cm) is protruding from each side of the cutting head. (Fig. 19)

4. Start the unit and bump the cutting head on the ground until the desired cutting length is achieved. Excess line will be trimmed off by the line blade.

NOTE: If the cutting line ends are pulled into

the cutting head or the line becomes twisted, refer to Removing the Line.

CHECKING THE OIL LEVEL

The importance of checking and maintaining the proper oil level in the crankcase cannot be overemphasized. Check oil before each use:

1. Stop the engine and allow oil to drain into the crankcase.

2. Place the unit on a flat, level surface to get a proper oil level reading.

3. Keep dirt, grass clippings and other debris out of the engine. Clean the area around the oil fill plug before removing it.

Flat-Head

Screw Driver

Arrows

Trimmer

Line

Dimple

Eyelet

Trimmer line

Bump Knob

FREQUENCY MAINTENANCE REQUIRED SEE

Every 10 hours Clean and oil air filter p. 8 After first 10 hours Change oil p. 8

Every 40 hours

Change oil Check rocker arm to valve clearance and adjust Check spark plug condition and gap

p. 8 p. 9 p. 9

Fig. 22

Fig. 21

Fig. 20

Fig. 19

WARNING: To prevent extensive

engine wear and damage to the unit, always maintain the proper oil level in the crankcase. Never operate the unit with a low oil level.

Fig. 23

O-Ring

Oil Fill Plug

WARNING: The cutting

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

9. Reinstall the rocker arm cover using a new gasket. Torque the screw to

20–30 in•lb (2.2–3.4 N•m).

10. Check the spark plug and reinstall. See Replacing the Spark Plug.

11. Replace the spark plug wire.

12. Reinstall the engine cover. Check alignment of the cover before tightening the screws. Tighten screws.

REPLACING THE SPARK PLUG

Use a replacement part number 753-05784 or Champion® RDZ4H spark plug. The correct air gap is 0.025 in. (0.635 mm).

1. Stop the engine and allow it to cool. Remove the two (2) screws on back of the engine cover and the one on the front of the engine cover with a Flat-head or T-25 Torx screwdriver (Fig. 31).

2. Grasp the plug wire firmly and pull the cap from the spark plug.

3. Clean dirt from 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 0.025 in. (0.635 mm) using a feeler gauge (Fig. 36).

4. Install a correctly-gapped spark plug in the cylinder head. Turn the 5/8 in. 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. CLEANING

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.

• Lock up the unit to prevent unauthorized use or damage.

• Store the unit in a dry, well-ventilated area.

• Store the unit out of the reach of children.

Short Term Storage (1-2 weeks)

1. Store the unit in a horizontal position. If this is not possible, store the unit vertically with the engine at the top.

Long Term Storage

1. Drain all gasoline from the gas tank into a container. Do not use gas that has been stored for more than 30 days. Dispose of the old gasoline in accordance with federal, state and local regulations.

2. Start the engine and allow it to run until it stalls. This ensures that all gasoline has been drained from the carburetor.

3. Allow the engine to cool. Remove the spark plug and put 5 drops of high quality motor 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.

4. Change the oil, referring to Changing the Oil. Dispose of the old oil in accordance with federal, state and local regulations.

5. 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.

NOTE: Careless adjustments can seriously damage your unit. An

authorized service dealer should make carburetor adjustments.

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

1. Start the engine and let it run at a high idle for a minute to warm up. Refer to 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 (Fig. 30). Turn the idle speed screw in, clockwise, 1/8 of a turn at a time (as needed) until the engine idles smoothly.

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

3. 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, cleaning the air filter, and adjusting the idle speed should solve most engine problems. If not and all of the following are 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.

ROCKER ARM CLEARANCE

This requires disassembly of the engine. If feeling unsure or unqualified to perform this, take the unit to an authorized service center.

• The engine must be cold when checking or

adjusting the valve clearance.

• This task should be performed inside in a

clean, dust free area.

1. Remove the two (2) screws on back of the engine cover and the one on the front of the engine cover with a Flat-head or T-25 Torx screwdriver (Fig. 31).

2. Remove the engine cover (Fig. 32).

3. Disconnect the spark plug wire.

4. Clean dirt from around the spark plug. Remove the spark plug from the cylinder head by turning a 5/8 in. socket counterclockwise.

5. Clean dirt from around the rocker arm cover. Remove the screw holding the rocker arm cover with a large flat blade screwdriver or Torx T-25 bit (Fig. 33). Remove the rocker arm cover and gasket.

6. Pull the starter rope slowly to bring the piston to the top of its travel, (known as top dead center). Check that:

• The piston is at the top of its travel while looking in the spark plug hole (Fig. 33)

• Both rocker arms move freely, and both valves are closed

If these statements are not true, repeat this step.

7. Slide the feeler gauge between the rocker arm and the valve return spring. Measure the clearance between the valve stem and rocker arm (Fig. 35). Measure both the intake and exhaust valves.

The recommended clearance for both intake and exhaust is .003 – .006 in. (.076 – 0.152 mm). Use a standard automotive .005 in. (0.127 mm) feeler gauge. The feeler gauge should slide between the r

ocker arm and valve stem with a slight amount of resistance, without binding. Figure 34 and 35 show how to measure the clearance.

8. If the clearance is not within specification:

a. Turn the adjusting nut using a 5/16 inch (8 mm) wrench or nut driver

(Fig. 35).

• To increase clearance, turn the adjusting nut counterclockwise.

• To decrease clearance, turn the adjusting nut clockwise. b. Recheck both clearances, and adjust as necessary.

Fig. 36

0.025 in.

(0.635 mm)

MAINTENANCE AND REPAIR INSTRUCTIONS

WARNING: To avoid serious personal injury, always turn the

unit off and allow it to cool before cleaning or servicing it.

WARNING: To avoid serious

personal injury, always turn the unit off and allow it to cool before cleaning or servicing it.

WARNING: Do not sand blast,

scrape or clean electrodes. Grit in the engine could damage the cylinder.

Rocker Arm

Cover

Fig. 33

Screw

Adjusting Nuts

Fig. 34

INTAKE

Valve Stem

Fig. 35

Exhaust

Adjusting

Nut

Feeler

Gauge

Rocker Arm

Rocker

Arms

EXHAUST

Spark

Plug Hole

0.003–0.006 in.

(0.076–0.152

mm)

Fig. 31

Fig. 32

Muffler

Remove Screws

Engine

Cover

CAUSE ACTION

Cutting attachment bound with grass

Stop the engine and clean cutting

attachment Cutting attachment out of line Refill with new line Line twisted when refilled Remove and rewind the line

Not enough line is exposed

Push the bump knob and pull out

line until 4 inches (102 mm) of line

is outside of the cutting attachment

Old fuel (over 30 days) Drain fuel tank and add fresh fuel Fouled spark plug Replace or clean the spark plug

The outside temperature is above 90˚ F

Move the choke lever to Position 2,

squeeze the throttle control and pull

the starter rope until the unit starts.

Operate the unit in Position 2.

Old fuel (over 30 days) Drain fuel tank and add fresh fuel Cutting attachment bound with

grass

Stop the engine and clean the

cutting attachment Dirty air filter Clean or replace the air filter

Empty fuel tank Fill fuel tank with fuel

Primer bulb wasn't pressed enough

Press primer bulb fully and slowly

10 times Old fuel (over 30 days) Drain fuel tank and add fresh fuel Fouled spark plug Replace or clean the spark plug

Engine is over heated

Move the choke lever to Position 2,

squeeze the throttle control and pull

the starter rope until the unit starts.

Run the unit for 2-5 minutes. Then

move the choke lever to Position 3.

Air filter is plugged Replace or clean the air filter Old fuel (over 30 days) Drain fuel tank and add fresh fuel

Improper idle speed

Adjust according to the Idle Speed

Adjustment section

ENGINE WILL NOT START

ENGINE WILL NOT ACCELERATE

ENGINE WILL NOT IDLE

If further assistance is required, contact your authorized service dealer.

TROUBLESHOOTING

ENGINE LACKS POWER OR STALLS WHEN CUTTING

* 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.

Engine Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air-Cooled, 4-Cycle

Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 cu. in. (25 cc)

Operating RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,800 - 9,300 rpm

Idle Speed RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,800 - 3,600 rpm

Valve clearance . . . . . . . . . . . . . . . . . . . . 0.003–0.006 in. (0.076–0.152 mm)

Spark Plug Gap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.025 inch (0.635 mm)

Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAE 30 Oil

Crankcase Oil Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 oz (60 ml)

Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Unleaded

Fuel Tank Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 oz (355 ml)

Approximate Unit Weight (without fuel). . . . . . . . . . . . . . . . . 14.5 lbs (5.4 kg)

Cutting Mechanism . . . . . . . . . . . . . . . . . . . . . . . . Professional Bump Head

Line Spool Diameter: . . . . . . . . . . . . . . . . . . . . . . . . . 3.25 inches (82.6 mm)

Trimming Line Diameter:. . . . . . . . . . . . . . . . . . . . . . 0.095 inches (2.41 mm)

Cutting Path Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 in. (45.7 cm.)

SPECIFICATIONS*

CUTTING ATTACHMENT WILL NOT ADVANCE LINE

ELECTRIC STARTER AND POWER START BIT™ FEATURES

This unit is designed to be started with an optional electric starter or Power Start Bit™ that are sold separately. If choosing to start the unit using one of these features or have questions please contact your local retailer or call 1-877-282-8684 U.S, (1-800-668-1238 Canada), for more information and purchasing. You may also go to www.cubcadet.com or www.cubcadet.ca.

Electric Start Feature

OPTIONAL ACCESSORY

+ 22 hidden pages

Cub Cadet ST426s Operator's Manual

Specifications and Main Features

Frequently Asked Questions

User Manual