Keep this owner’s manual handy, so you can refer to it at any time. This owner’s manual is considered a permanent part of the trimmer/brush cutter and should remain with the trimmer/brush cutter if resold. The information and specifications included in this publication were in effect at the time of approval for printing.
We want to help you get the best results from your new trimmer/brush cutter and to operate it safely. This manual contains the information on how to do that; please read it carefully.
INTRODUCTION A FEW WORDS ABOUT SAFETY Your safety, and the safety of others, are very important. And using this trimmer/brush cutter safely is an important responsibility. To help you make informed decisions about safety, we have provided operating procedures and other information on labels and in this manual.
TRIMMER SAFETY IMPORTANT SAFETY INFORMATION The Honda HHT25S and HHT31S trimmer/brush cutters are designed to cut grass, weeds, brush, and/or wood if equipped with an appropriate cutting attachment. Other uses can result in injury to the operator or damage to the trimmer and other property.
As an employer, you have special responsibilities to the people who work for you. Before you ask anyone to operate this trimmer/ brush cutter, you need to determine whether the operator is old enough, large enough, and strong enough to safely handle and control the trimmer/ brush cutter.
The labels shown here contain important safety information. Please read them carefully. These labels are considered permanent parts of your trimmer/brush cutter. If a label comes off or becomes hard to read, contact an authorized Honda servicing dealer for a replacement.
RECOMMENDED CUTTING ATTACHMENTS CUTTING-LINE HEADS AND SHIELDS A cutting-line head containing nylon monofilament line, and a debris shield with cutoff knife is standard equipment. The shield’s cutoff knife automatically removes any excess line that is released from the cutting head. Honda HHT31SUNBA model trimmers are supplied with two different debris shields.
RECOMMENDED CUTTING ATTACHMENTS BLADES AND SHIELDS A variety of blades are available from your Honda trimmer servicing dealer. Always use a debris shield designed for use with a blade when attaching a blade to your trimmer. The blade type debris shield does not have a cutoff knife. Honda HHT31SUNBA trimmers are supplied with a blade cover surrounding the edge of the blade.
Remove the blade cover in the reverse order of installation. CUTTING ATTACHMENT APPLICATIONS HHT25S HHT31S GRASS AND LIGHT WEEDS THICK WEEDS AND LIGHT BRUSH WOODY BRUSH, SHRUBS, SAPLINGS Your Honda trimmer servicing dealer has cutting attachments that have been designed and approved for your trimmer and are covered by warranty.
CONTROLS The location and operation of the controls are similar on both the HHT25S and HHT31S models. Choke Lever The choke lever opens and closes the choke valve. The CLOSED position enriches the fuel mixture for starting a cold engine.
CONTROLS & EQUIPMENT Throttle Set Button The throttle set button is used to hold the throttle trigger at the fast idle position for starting. Do not allow the cutting line or blade to contact any obstruction when starting the engine with the throttle set button engaged.
CONTROLS & EQUIPMENT EQUIPMENT FULL SHOULDER HARNESS (UNBA only) The Honda HHT25S and HHT31S trimmer/brush cutters are supplied with a shoulder harness and safety glasses. Refer to page 14 for a description of other equipment and protective clothing you will need.
BEFORE OPERATION ARE YOU READY TO OPERATE THE TRIMMER? Your safety is your responsibility. A little time spent in preparation will significantly reduce your risk of injury. Knowledge Read and understand this manual. Know what the controls do and how to operate them. Familiarize yourself with the trimmer and its operation before you begin to use it.
IS YOUR TRIMMER READY TO GO? For your safety, and to maximize the service life of your equipment, it is very important to take a few moments before you operate the trimmer to check its condition. Be sure to take care of any problem you find, or have your servicing dealer correct it, before you operate the trimmer.
BEFORE OPERATION ARE YOUR SHOULDER HARNESS AND TRIMMER CORRECTLY ADJUSTED? Adjusting the Harness Adjust the harness so the quick-release latch is at your right hip, as shown. QUICK-RELEASE LATCH FULL SHOULDER HARNESS QUICK-RELEASE LATCH SINGLE-STRAP SHOULDER HARNESS Balancing the Trimmer on the Shoulder Harness Hang the trimmer on the harness hook, and see how it balances.
OPERATION SAFE OPERATING PRECAUTIONS Before operating the trimmer for the first time, please review the IMPORTANT SAFETY INFORMATION chapter on page 4 and BEFORE OPERATION chapter starting on page 14. Even if you have operated other trimmers, take time to become familiar with the operation of this trimmer’s controls and handling.
OPERATION 5. Set the trimmer on the ground, resting on the debris shield and the fuel tank guard. Do not allow the cutting-line or blade to contact any obstruction. Always rest the trimmer on the ground for starting, rather than holding it in the operating position.
STOPPING THE ENGINE 1. Release the throttle trigger. 2. Move the ignition switch to the STOP (O) position. Wait for the cutting line head or blade to stop before allowing the end of the trimmer to contact anything. WARNING The blade will continue to spin briefly after the engine has stopped or the throttle trigger is released.
OPERATION Throttle Operation Pull the throttle trigger toward the grip to increase engine speed and start cutting attachment rotation. The trimmer has the greatest cutting force at maximum engine speed. Release the throttle trigger to reduce engine speed. At idle, the cutting attachment should coast to a stop.
The trimmer will throw debris in the direction of blade movement at the point of contact. The cutting line head or blade on Honda HHT25S and HHT31S trimmers rotate counterclockwise, as viewed from the operator’s position, so tilting the cutting line head to the right will throw debris away from you, and tilting to the left will throw debris toward you.
Blades on Honda HHT25S and HHT31S trimmers rotate counterclockwise, as viewed from the operator’s position. Therefore, the left side of the blade is moving toward you. With these trimmers, sawing with the left side of a brush blade will give you better control and less risk of kickback, though it will throw the sawdust toward you.
OPERATION Trimming and Edging Use nylon line for cutting against a hard surface. Work from an angle where debris that strikes the hard surface will ricochet away from you. DEBRIS Avoid contact with wires, wire fences, metal rods, etc. Overlapping a wire will cause the nylon line to wrap around the wire and break off.
SERVICING YOUR HONDA TRIMMER THE IMPORTANCE OF MAINTENANCE Good maintenance is essential for safe, economical, and trouble-free operation. It will also help reduce air pollution. WARNING Improperly maintaining this trimmer, or failure to correct a problem before operation, can cause a malfunction in which you can be seriously hurt or killed.
(see page 27). HHT25S 2.7 fl oz (80 cc) Engine oil capacity: HHT31S 3.4 fl oz (100 cc) 3. Screw in the filler cap/dipstick securely. FILLER OPENING (HHT31S) OIL FILLER...
3. Wipe dirt from the air cleaner base and cover using a moist rag. Be careful to prevent dirt from entering the carburetor. SERVICING YOUR HONDA TRIMMER FILTER LATCH RETAINING TABS AIR CLEANER COVER HHT25S RETAINING TABS AIR CLEANER COVER LATCH HHT31S FILTER...
Throttle Cable Adjustment 1. Loosen the lock nut with a 10 mm wrench, and turn the adjusting nut in or out as required. 2. Tighten the lock nut and recheck cable free play. HHT31S LOCK NUT CABLE END FREE PLAY 1/16 ~ 1/8 in (1.0 –...
Honda trimmers come standard with low noise line. Using non-Honda line may result in increased noise levels. For original, factory-installed Honda cutting-line heads, use only nylon monofilament line in the line sizes shown below. Line Size Model HHT25S HHT31S 0.095" 0.105"...
SERVICING YOUR HONDA TRIMMER Manual Cutting-Line Head 1. Clean any mud, dirt, debris, etc. from the area around the trimmer head; otherwise, it will make it more difficult to service. 2. Rotate the left-hand threaded knob in the direction of the arrow and remove the knob. Remove the spring and spool from the housing then remove any remaining old line from the spool.
5. When you have about 6 inches (150 mm) of line remaining, press the lines into the two notches on the bottom of the spool. This will hold the lines on the spool for reassembly. 6. Feed both line ends through the metal eyelets in the housing.
SERVICING YOUR HONDA TRIMMER Semi-Matic (Bump-Feed) Cutting-Line Head 1. Clean any mud, dirt, debris, etc., from around the trimmer head area; otherwise, it will make it more difficult to service. 2. Locate the half-round locking hole on the spool. 3. It may be necessary to lightly rotate the spool in the direction of the arrow about an 1/8 turn until the spool stops.
7. Wind both lines tightly and evenly from side to side ignoring the ridge. Feed the line while turning the spool in the direction of the arrow. Do not allow the line to get twisted. It is important to prevent the two lines from getting twisting over each other.
SERVICING YOUR HONDA TRIMMER Removal & Installation This section shows you how to remove and install either style trimmer head from your trimmer. 1. Insert the tip of a commercially available 4 mm hex wrench or equivalent fully into the gear case hole.
Blade Blade Inspection Always wear gloves when working around the blade. Before each use, check the blade for wear and damage, and check the tightness of the blade lock nut. Examine the entire head area, including the debris shield, and clear or clean it free from dirt, debris, loose string, wire, or any other foreign materials.
SERVICING YOUR HONDA TRIMMER 1. Install the protective plastic cover, that came with the blade, back on the blade. 2. Insert a commercially available 4 mm hex tool or equivalent fully into the gear case hole. 3. Turn the blade until you feel the tool drop into the hole in cover plate/spacer A.
Spark Plug Service Recommended spark plugs: HHT25S CMR5HSB (NGK) HHT31S CR5HSB (NGK) U16FSR-UB (DENSO) NOTICE Incorrect spark plugs can cause engine damage. 1. HHT25S model: Remove the 5 x 12 mm hex bolt and top cover. 2. Disconnect the spark plug cap, and remove any dirt from around the spark plug area.
SERVICING YOUR HONDA TRIMMER Spark Arrester Service HHT31S The spark arrester must be serviced every 100 hours to keep it functioning as designed. If the engine has been running, the muffler will be very hot. Allow the muffler to cool before servicing the spark arrester.
HHT25S The spark arrester must be serviced every 100 hours to keep it functioning as designed. If the engine has been running, the muffler will be very hot. Allow the muffler to cool before servicing the spark arrester. 1. Remove the 5 x 12 mm hex bolt and top cover 2.
Refueling Fuel tank capacities: HHT25S: 0.53 qt/16.9 fl oz (0.50 ) HHT31S: 0.69 qt/22.0 fl oz (0.65 ) Check the fuel level by looking through the translucent fuel tank. If the fuel level is low, refuel in a well-ventilated area with the engine stopped.
Inspect the engine cooling fins, and clean out any dirt and debris. On both the HHT25S and HHT31S, it is necessary to remove the top cover. Removal procedures are located on page 37 for HHT25S and page 38 for the HHT31S.
ASSEMBLY After assembly and before operation review the Safe Operating Precautions on page 17. IMPORTANCE OF PROPER ASSEMBLY Proper assembly is essential to operator safety and the reliability of the machine. Any error or oversight made by the person assembling and servicing a machine can result in faulty operation, damage to the machine, or injury to the operator.
ASSEMBLY TRIMMER ASSEMBLY (UNBA types only) U-Shaped Handlebar Installation 1. Remove the four 5 x 28 mm bolt/washers and handlebar holder A. 2. Set the U-shaped handle into handlebar holder B with the throttle trigger facing to the right. 3. Adjust the handlebar position as shown. 4.
Saw Blade The UNBA types are shipped with a manual nylon cutting-line head installed on the trimmer. If the saw blade is needed, move the ignition switch to the STOP (O) position and disconnect the spark plug cap from the spark plug. Wear protective gloves when working around the cutting-line head and saw blade. Cutting-Line Head Removal 1.
ASSEMBLY Saw Blade Installation 1. Insert a 4 mm hex wrench or equivalent into the gear case hole to prevent the output shaft from turning. 2. Install cover plate/spacer A onto the output shaft as shown. 3. With the blade cover installed on the blade, install the blade, by aligning the center of the blade with the shoulder on cover plate/spacer 4.
BLADE COVER REMOVAL 1. Turn the blade cover slowly until the cover latch is clear of the debris shield. Unfasten the latch by lifting the tab off the post. 2. Pull the post end away from the blade and set it on top of the blade as shown. 3.
Do not overfill, as the engine oil tank capacity is small. Engine oil capacity: HHT25S 2.7 fl oz (80 cc) HHT31S 3.4 fl oz (100 cc) NOTICE Running the engine with too little or too much oil can cause engine damage.
STORAGE STORAGE PREPARATION Proper storage preparation is essential to keep your trimmer trouble free and looking good. The following steps will help to keep rust and corrosion from impairing your trimmer's function and appearance, and will make the engine easier to start when you use the trimmer again.
STORAGE Adding Fuel Stabilizer to Extend Fuel Storage Life When adding a fuel stabilizer, fill the fuel tank with fresh gasoline. If only partially filled, air in the tank will promote fuel deterioration during storage. If you keep a container of gasoline for refueling, be sure that it contains only fresh gasoline.
TRANSPORTING BEFORE LOADING If the engine has been running, allow it to cool for at least 15 minutes before loading the trimmer on the transport vehicle. A hot engine and exhaust system can burn you and can ignite some materials. Always turn the ignition switch to the STOP (O) position.
TAKING CARE OF UNEXPECTED PROBLEMS STARTING PROBLEMS Engine Will Not Start Check control positions. Check fuel. Remove spark plug. Take trimmer to an authorized Honda servicing dealer, or refer to shop manual. ENGINE OPERATING PROBLEMS Low Power or Engine Speed Won’t Increase Check air filter.
CUTTING HEAD PROBLEMS Blade or Cutting-line head Won’t Stop Turning When Throttle is at SLOW Position Check throttle control and cable. Check clutch. Blade or Cutting-Line Head Won’t Turn Check clutch, drive cable, and gear case. Excessive Vibration Check cutting-line head or blade nut.
ENGINE SERIAL NUMBER HHT31S Carburetor Modifications for High Altitude Operation At high altitude, the standard carburetor air-fuel mixture will be too rich. Performance will decrease, and fuel consumption will increase. A very rich mixture will also foul the spark plug and cause hard starting.
Oxygenated Fuels Some conventional gasolines are being blended with alcohol or an ether compound. These gasolines are collectively referred to as oxygenated fuels. To meet clean air standards, some areas of the USA and Canada use oxygenated fuels to help reduce emissions. If you use an oxygenated fuel, be sure it is unleaded and meets the minimum octane rating requirement.
TECHNICAL & CONSUMER INFORMATION Emissions Control System Information Source of Emissions The combustion process produces carbon monoxide, oxides of nitrogen, and hydrocarbons. Control of hydrocarbons and oxides of nitrogen is very important because, under certain conditions, they react to form photochemical smog when subjected to sunlight.
Descriptive Term Moderate Intermediate Extended The Air Index Information hang tag/label must remain on the trimmer/brush cutter until it is sold. Remove the hang tag before operating the trimmer/brush cutter. TECHNICAL & CONSUMER INFORMATION Applicable to Emissions Durability Period 50 hours (0–65 cc) 125 hours (greater than 65 cc) 125 hours (0–65 cc)
HHT25S Manual feed — head Semi-matic 6.12 feet (1.867 m) feed head — — 9.6 in (245 mm) — 13.0 lb. (5.89 kg) — HHT31S HHT31SUNBA • • • • optional • • optional optional • HHT31S 6.15 feet (1.875 m) 6.18 feet (1.885 m)
Clutch Drive Type Tuneup ITEM Spark plug gap HHT25S Valve clearance (cold) HHT31S TECHNICAL & CONSUMER INFORMATION ENGINE HHT25S GX25 1.5 cu in (25 cc) 1.4 x 1.0 in (35 x 26 mm) • m) at 5,000 rpm Transistorized magneto...
Call (800) 426-7701 or visit our website: www.hondapowerequipment.com/dealer Warranty Service Information Honda Power Equipment dealership personnel are trained professionals. They should be able to answer any question you may have. If you encounter a problem that your dealer does not solve to your satisfaction, please discuss it with the dealership's management.