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Honda HHT25S Manual

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SERVICE INFORMATION
The service and repair information contained in this manual is intended for use by qualified, professional technicians.
Attempting service or repairs without the proper training, tools, and equipment could cause injury to you or others. It could
also damage the trimmer/brush cutter or create an unsafe condition.
This manual describes the proper methods and procedures for performing service, maintenance, and repairs. Some
procedures require the use of special tools. Any person who intends to use a replacement part, service procedure, or a
tool that is not recommended by Honda, must determine the risks to their personal safety and the safe operation of the
trimmer/brush cutter.
If you need to replace a part, use genuine Honda parts with the correct part number, or an equivalent part. We strongly
recommend that you do not use replacement parts of inferior quality.
FOR YOUR CUSTOMER'S SAFETY
Proper service and maintenance are essential to the customer's
safety and the reliability of the trimmer/brush cutter. Any error or
oversight while servicing a trimmer/brush cutter can result in faulty
operation, damage to the trimmer/brush cutter, or injury to others.
FOR YOUR SAFETY
Because this manual is intended for the professional service
technician, we do not provide warnings about many basic shop
safety practices (e.g., Hot parts – wear gloves). If you have not
received shop safety training or do not feel confident about your
knowledge of safe servicing practices, we recommend that you do
not attempt to perform the procedures described in this manual.
Some of the most important general service safety precautions are
given below. However, we cannot warn you of every conceivable
hazard that can arise in performing service and repair procedures.
Only you can decide whether or not you should perform a given
task.
IMPORTANT SAFETY PRECAUTIONS
• Make sure you have a clear understanding of all basic shop safety practices and that you are wearing appropriate
clothing and using safety equipment. When performing any service task, be especially careful of the following:
Read all of the instructions before you begin, and make sure you have the tools, the replacement or repair parts, and
the skills required to perform the tasks safely and completely.
Protect your eyes by using proper safety glasses, goggles, or face shields anytime you hammer, drill, grind, or work
around pressurized air or liquids, and springs or other stored-energy components. If there is any doubt, put on eye
protection.
Use other protective wear when necessary, for example, gloves or safety shoes. Handling hot or sharp parts can
cause severe burns or cuts. Before you grab something that looks like it can hurt you, stop and put on gloves.
• Make sure the engine is off before you begin any servicing procedures, unless the instructions tell you to do otherwise.
This will help eliminate several potential hazards:
Carbon monoxide poisoning from engine exhaust. Be sure there is adequate ventilation whenever you run the
engine.
Burns from hot parts. Let the engine and exhaust system cool before working in those areas.
Injury from moving parts. If the instruction tells you to run the engine, be sure your hands, fingers, and clothing are
out of the way.
• Gasoline vapors are explosive. To reduce the possibility of a fire or explosion, be careful when working around
gasoline.
Use only a nonflammable solvent, not gasoline, to clean parts.
Never drain or store gasoline in an open container.
Keep all cigarettes, sparks, and flames away from all fuel-related parts.
A FEW WORDS ABOUT SAFETY
B WARNING
Improper service or repairs can create an unsafe
condition that can cause your customer or others
to be seriously hurt or killed.
Follow the procedures and precautions in this
manual and other service materials carefully.
B WARNING
Failure to properly follow instructions and
precautions can cause you to be seriously hurt
or killed.
Follow the procedures and precautions in this
manual carefully.

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  Summary of Contents for Honda HHT25S

  • Page 1 Honda, must determine the risks to their personal safety and the safe operation of the trimmer/brush cutter. If you need to replace a part, use genuine Honda parts with the correct part number, or an equivalent part. We strongly recommend that you do not use replacement parts of inferior quality.
  • Page 2 INTRODUCTION CONTENTS This manual covers service and repair procedures for the SPECIFICATIONS Honda HHT25S and HHT35S Trimmer/Brush Cutter. All information contained in this manual is based on the latest SERVICE INFORMATION product information available at the time of printing. We reserve the right to make changes at any time without notice.
  • Page 4 3. WIRING DIAGRAM....2. DIMENSIONAL DRAWINGS ... . 1. SPECIFICATIONS DIMENSIONS, WEIGHTS, AND CAPACITIES Model HHT25S HHT35S Type LTAT LTAT...
  • Page 5 SPECIFICATIONS HHT25S•HHT35S ENGINE Trimmer model HHT25S HHT35S Engine model GX25 GX35 Description code GCAAM GCACM, GCAST Engine type 4-stroke, overhead cam, single cylinder Displacement 25 cm³ (1.5 cu in) 35.8 cm³ (2.20 cu in) Bore x stroke 35 x 26 mm (1.4 x 1.0 in) 39 x 30 mm (1.5 x 1.2 in)
  • Page 6 HHT25S•HHT35S SPECIFICATIONS FRAME Throttle control type Two-motion trigger type 25.4 mm (1.0 in) Frame type Thickness 1.5 mm (0.06 in) Material Flexible steel cable Type 6.3 mm (0.25 in) Drive Engagement 5 mm (0.2 in) square drive both ends Material...
  • Page 7 SPECIFICATIONS HHT25S•HHT35S 2. DIMENSIONAL DRAWINGS HHT25S 245 mm (9.6 in) 323 mm (12.7 in)
  • Page 8 HHT25S•HHT35S SPECIFICATIONS HHT35S LOOP TYPE HANDLE overall height 260 mm (10.2 in) overall width 325 mm (12.8 in)
  • Page 9 SPECIFICATIONS HHT25S•HHT35S HHT35S U-TYPE HANDLEBAR overall height 405 mm (15.9 in) overall width 600 mm (23.6 in)
  • Page 10 HHT25S•HHT35S SPECIFICATIONS 3. WIRING DIAGRAM Black IGNITION CONTROL MODULE (ICM) Black SPARK PLUG IGNITION COIL ENGINE SWITCH Black/white...
  • Page 11 SPECIFICATIONS HHT25S•HHT35S...
  • Page 12 8. TROUBLESHOOTING ....1. SERVICE RULES • Use genuine Honda parts or their exact equivalent. Lower quality parts can damage the trimmer/brush cutter or reduce its performance.
  • Page 13 SERVICE INFORMATION HHT25S•HHT35S 3. ABBREVIATIONS Throughout this manual, the following abbreviations are used to identify the respective parts or systems. Abbreviated term Full term American Petroleum Institute Approx. Approximately Assy. Assembly ATDC After Top Dead Center Attachment Bottom Dead Center...
  • Page 14 HHT25S•HHT35S SERVICE INFORMATION 4. SERIAL NUMBER LOCATIONS The engine serial number is located on the crankcase, near the fuel tank. Refer to the engine serial number when ordering parts and when making technical inquiries. The frame serial number is located on the frame pipe.
  • Page 15 SERVICE INFORMATION HHT25S•HHT35S 5. SERVICE SPECIFICATIONS HHT25S Part Item Standard Service Limit Idle speed 3,100 ± 200 rpm —————————— Engine Cylinder compression —————————— 0.90 ~ 1.10 Mpa (131 ~ 159 psi) at 2,000 min (rpm) Cylinder Sleeve I.D. 35.000 - 35.015 mm (1.378 - 1.379 in) 35.100 mm (1.3819 in)
  • Page 16 HHT25S•HHT35S SERVICE INFORMATION HHT35S Part Item Standard Service Limit Idle speed 3,100 ± 200 rpm —————————— Engine Cylinder compression —————————— 0.95 ± 0.15 Mpa (138 ± 22 psi) at 2,000 min (rpm) Cylinder Sleeve I.D. 39.000 - 39.015 mm (1.5345 - 1.536 in) 39.100 mm (1.5393 in)
  • Page 17 SERVICE INFORMATION HHT25S•HHT35S 6. TORQUE VALUES TORQUE THREAD DIAMETER ITEM (mm) N•m kg•m ft•lb in•lb Lower crankcase M5 Socket bolt (CT) 0.65 Fan cover HHT25S M4 Screw Oil outlet valve plate HHT35S M4 Screw 0.30 HHT25S M4 Socket bolt Ignition coil...
  • Page 18 HHT25S•HHT35S SERVICE INFORMATION STANDARD TORQUE VALUES TORQUE THREAD DIAMETER STANDARD FASTENERS (mm) N•m kg•m ft•lb in•lb Screw 16.8 0.42 0.90 Bolt and nut 0.53 Flange bolt and flange nut 7. SPECIAL TOOLS TOOL NAME TOOL NUMBER APPLICATION Piston base 07VPF-ZM3010B...
  • Page 19 SERVICE INFORMATION HHT25S•HHT35S 8. TROUBLESHOOTING GENERAL SYMPTOMS AND PROBABLE CAUSES Fuel in the carburetor is old. Engine does not start or is hard Drain the old fuel and then to start. inspect and clean the carburetor P. 5-3, P. 5-8.
  • Page 20 HHT25S•HHT35S SERVICE INFORMATION Engine speed does not increase. Carburetor problem. Adjust 5-5, 5-10. Disassemble/clean 5-3, P. 5-8 Ignition coil faulty. Inspect 7-8, 7-14. Inspect/replace 3-11, 2-14. Spark plug faulty. Poor performance at high speed. Carburetor restricted. Adjust 5-5, 5-10. Disassemble/clean 5-3, P.
  • Page 21 SERVICE INFORMATION HHT25S•HHT35S HARD STARTING SERVICE BULLETIN #5 => No fuel in the tank Check the fuel level. Refuel. Sufficient fuel Not reaching the carburetor Check whether fuel is reaching the • Check for restriction in the fuel tube carburetor by pressing the priming bulb.
  • Page 22 HHT25S•HHT35S SERVICE INFORMATION POOR PERFORMANCE AT LOW SPEED Restricted Check the air cleaner element 3-3. Clean the air cleaner element. Replace if necessary 3-3. Not restricted Plugged Check for a restricted spark arrester. Clean or replace as necessary 3-12. Normal...
  • Page 23 SERVICE INFORMATION HHT25S•HHT35S POOR PERFORMANCE AT HIGH SPEED Restricted Check the air cleaner element 3-3. Clean the air cleaner element. Replace if necessary 3-3. Not restricted Abnormal Remove the spark plug and check for Adjust the plug gap; replace if chipped,...
  • Page 24 HHT25S•HHT35S SERVICE INFORMATION IGNITION SYSTEM Measure the spark plug gap and perform the spark test 2-14. Gap: 0.6~0.7 mm (0.024~0.028 in) No spark Good spark Replace the spark plug with a new one Keep the new spark plug. and check for spark.
  • Page 25 SERVICE INFORMATION HHT25S•HHT35S SPARK TEST  WARNING Gasoline is highly flammable and explosive. If ignited, gasoline can burn you severely. Before testing the spark plug: • Be sure there is no spilled fuel near the engine. • Place the spark plug away from the spark plug hole.
  • Page 26 HHT25S•HHT35S SERVICE INFORMATION PROBABLE CAUSES OF MAJOR CARBURETOR PROBLEMS Symptom High Acceleration/ Starting Low speed speed deceleration Probable causes Throttle stop screw out of adjustment Fuel filter restricted Fuel line restricted Fuel tank/line Air mixing in fuel passage Incorrect/deteriorated fuel...
  • Page 27 SERVICE INFORMATION HHT25S•HHT35S EXCESSIVE VIBRATION If a trimmer head is installed, check the Abnormal Rewind the line on the trimmer head trimmer head for proper winding and 10-5, 10-6. even line length 10-5, 10-6. Normal Damaged If a blade is installed, check the blade Replace the blade 10-8.
  • Page 28 HHT25S•HHT35S SERVICE INFORMATION CUTTER DOES NOT ROTATE Worn out Check whether the clutch shoes are Replace the clutch assembly 7-6, 7-11. worn out 7-6, 7-11. Normal Damaged Check the drive cable for damage Replace the drive cable 11-14. 11-14. Normal...
  • Page 29 SERVICE INFORMATION HHT25S•HHT35S 2-18...
  • Page 30 3. MAINTENANCE 1. MAINTENANCE SCHEDULE ....8. VALVE CLEARANCE ADJUSTMENT . 3-10 2. ENGINE OIL ......9.
  • Page 31 MAINTENANCE HHT25S•HHT35S 2. ENGINE OIL LEVEL CHECK OIL FILLER CAP/DIPSTICK Check the engine oil level before each use. Check the oil with the engine stopped and the engine on a level surface. 1. Remove the oil filler cap/dipstick and wipe it clean.
  • Page 32 -5°C ~ 40°C (23°F ~ 104°F) ambient temperature The SAE oil viscosity and service classification are on the API label on the oil container. Honda recommends that you use API SERVICE category SJ or later oil. 6. Screw in the filler cap/dipstick securely.
  • Page 33 MAINTENANCE HHT25S•HHT35S 4. THROTTLE CABLE THROTTLE INSPECTION CABLE END 1. Remove the air cleaner cover. 2. Move the throttle lever lightly and check the carburetor side SWIVEL throttle cable free play. 1 ~ 3 mm Throttle cable free play 1.0 ~ 3.0 mm (1/16 ~ 1/8 in) (1/16 ~ 1/8 in) 3.
  • Page 34 HHT25S•HHT35S MAINTENANCE 5. CUTTING LINE REPLACEMENT HOUSING Always use the correct nylon monofilament cutting line diameter. Cutting-line head removal is not necessary to replace the line. Head removal is covered in “CUTTING ATTACHMENT / GEAR CASE” SHAFT page 10-1. SPOOL MANUAL CUTTING-LINE HEAD 1.
  • Page 35 MAINTENANCE HHT25S•HHT35S 7. When you have about 150 mm (6 inches) 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. NOTCHES 8. Feed both line ends through the metal eyelets in the housing.
  • Page 36 HHT25S•HHT35S MAINTENANCE SEMI-MATIC CUTTING LINE HEAD SPOOL 1. Clean any mud, dirt, debris, etc., from around the trimmer head area. Otherwise, servicing the trimmer will be more difficult. 2. Locate the half-round locking hole on the spool. HALF-ROUND LOCKING HOLE 3.
  • Page 37 MAINTENANCE HHT25S•HHT35S 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 lines to get twisted. It is important to prevent the two lines from getting twisting over each other.
  • Page 38 HHT25S•HHT35S MAINTENANCE KWIK LOADER CUTTING-LINE HEAD HOUSING To load, push the trimmer line into the housing until a minimum of 6 mm LINE (0.25 in) length is exposed in the inner housing. Do this equally for both (push to load in sides.
  • Page 39 MAINTENANCE HHT25S•HHT35S 8. VALVE CLEARANCE ADJUSTMENT 5 mm Valve clearance inspection and adjustment must be performed with the TOP COVER engine cold. BOLT 1. Loosen the 5 mm hex bolt and remove the top cover. TOP COVER 2. Remove the two 5 x 12 mm hex bolts from the head cover.
  • Page 40 HHT25S•HHT35S MAINTENANCE 9. SPARK PLUG SERVICE Standard spark plug NGK – CMR5H NOTICE An incorrect spark plug can cause engine damage. If the engine has been running, it will be very hot. Allow the engine to cool before proceeding. 1. Loosen the 5 mm top cover bolt, and then remove the cover.
  • Page 41 1. Loosen the captive 5 mm hex bolt, and then remove the top cover. MUFFLER 2. Remove the two (HHT25S) or three (HHT35S) 4 x 6 mm self- MUFFLER tapping screws from the spark arrester, and remove the spark arrester from the muffler.
  • Page 42 HHT25S•HHT35S MAINTENANCE 11. GEAR CASE 10 mm HEX BOLT GREASING 1. Move the ignition switch to the STOP position and disconnect the spark plug cap from the spark plug. 2. Remove the 8 x 10 mm hex bolt from the gear case.
  • Page 43 MAINTENANCE HHT25S•HHT35S 12. FUEL TANK / FUEL FILTER  WARNING Gasoline is highly flammable and explosive. You can be burned or seriously injured when handling fuel. • Keep heat, sparks, and flame away. • Handle fuel only outdoors. • Wipe up spills immediately.
  • Page 44 4. TOP COVER / MUFFLER 1. HHT25S REMOVAL/INSTALLATION ..2. HHT35S REMOVAL/INSTALLATION ..1. HHT25S REMOVAL/INSTALLATION  CAUTION The engine and muffler become very hot during operation and they remain hot for a while after operation. Be sure that the engine is cold before muffler removal/installation.
  • Page 45 TOP COVER / MUFFLER HHT25S•HHT35S 2. HHT35S REMOVAL/INSTALLATION  CAUTION The engine and muffler become very hot during operation and they remain hot for a while after operation. Be sure that the engine is cold before muffler removal/installation. 5 mm TOP COVER BOLT 3.0 N•m (0.3 kg•m, 27 in•lb)
  • Page 46 5. AIR CLEANER / CARBURETOR 1. HHT25S AIR CLEANER ....3. HHT35S AIR CLEANER ....
  • Page 47 AIR CLEANER / CARBURETOR HHT25S•HHT35S 2. HHT25S CARBURETOR REMOVAL/INSTALLATION Before removal, completely drain the carburetor.  WARNING Gasoline is highly flammable and explosive. You can be burned or seriously injured when handling fuel. • Keep heat, sparks, and flame away.
  • Page 48 HHT25S•HHT35S AIR CLEANER / CARBURETOR DISASSEMBLY/REASSEMBLY  WARNING Gasoline is highly flammable and explosive. You can be burned or seriously injured when handling fuel. • Keep heat, sparks, and flame away. • Handle fuel only outdoors. • Wipe up spills immediately.
  • Page 49 AIR CLEANER / CARBURETOR HHT25S•HHT35S ADJUSTMENT: P. 5-5...
  • Page 50 HHT25S•HHT35S AIR CLEANER / CARBURETOR METERING LEVER ADJUSTMENT 1. Install the metering body spring, inlet needle valve, metering 1.18 ~ 1.50 mm lever, metering lever pin, and the metering lever pin screw on (0.046 ~ 0.059 in) the pump body.
  • Page 51 AIR CLEANER / CARBURETOR HHT25S•HHT35S 3. HHT35S AIR CLEANER REMOVAL/INSTALLATION NOTICE If these parts are left out or not attached, dirt will enter the intake system and damage the engine. AIR CLEANER CASE REASSEMBLY: Before installation, clean inside the case with compressed air.
  • Page 52 HHT25S•HHT35S AIR CLEANER / CARBURETOR 4. HHT35S CARBURETOR REMOVAL/INSTALLATION  WARNING Gasoline is highly flammable and explosive. You can be burned or seriously injured when handling BREATHER TUBE fuel. INSTALLATION: • Keep heat, sparks, and flame away. Note the installation direction.
  • Page 53 AIR CLEANER / CARBURETOR HHT25S•HHT35S DISASSEMBLY / REASSEMBLY  WARNING Gasoline is highly flammable and explosive. You can be burned or seriously injured when handling fuel. • Keep heat, sparks, and flame away. • Handle fuel only outdoors. • Wipe up spills immediately.
  • Page 54 HHT25S•HHT35S AIR CLEANER / CARBURETOR METERING DIAPHRAGM GASKET Do not reuse. METERING DIAPHRAGM INLET NEEDLE VALVE CHECK VALVE REASSEMBLY: REASSEMBLY: Replace the metering diaphragm if Check for worn valve seat, valve, it is deteriorated, stiff, or damaged. or weak spring before installation.
  • Page 55 AIR CLEANER / CARBURETOR HHT25S•HHT35S METERING LEVER ADJUSTMENT 1. Install the metering body spring, inlet needle valve, metering lever, metering lever pin, and the metering lever pin screw on 1.18 ~ 1.50 mm (0.046 ~ 0.059 in) the pump body.
  • Page 56 3. HHT35S RECOIL STARTER ... . 2. HHT25S FUEL TANK....4. HHT35S FUEL TANK ....
  • Page 57 RECOIL STARTER / FUEL TANK HHT25S•HHT35S REASSEMBLY  CAUTION • Wear gloves and eye protection. • During disassembly, take care not to allow the return spring to come out. 1. Insert the hook on the outer side of the spring into the groove inside the starter reel.
  • Page 58 HHT25S•HHT35S RECOIL STARTER / FUEL TANK 5. Pass the starter rope end through the case and pull it outward. Pass the starter rope through the starter handle and tie the rope so that it can be untied easily by pulling it as shown.
  • Page 59 RECOIL STARTER / FUEL TANK HHT25S•HHT35S FUEL TANK HHT25S (See page 1-2 for serial numbers) REMOVAL/INSTALLATION Before removal, completely drain the fuel tank and fuel line.  WARNING Gasoline is highly flammable and explosive. You can be burned or seriously injured when handling fuel.
  • Page 60 HHT25S•HHT35S RECOIL STARTER / FUEL TANK 3. HHT35S RECOIL STARTER REMOVAL/INSTALLATION RECOIL STARTER ASSEMBLY DISASSEMBLY/REASSEMBLY: P. 6-1, 6-2 P. 6-1 5 x 16 mm SOCKET BOLT (3) DISASSEMBLY  CAUTION SET SCREW • Wear gloves and eye protection. • During disassembly, take care not to allow the return spring to come out.
  • Page 61 RECOIL STARTER / FUEL TANK HHT25S•HHT35S REASSEMBLY RECOIL STARTER SPRING HOOK  CAUTION • Wear gloves and eye protection. • During disassembly, take care not to allow the return spring to come out. GROOVE 1. Insert the hook on the outer side of the spring into the groove inside the starter reel.
  • Page 62 HHT25S•HHT35S RECOIL STARTER / FUEL TANK 7. Unhook the starter rope from the cutout of the starter reel. SLIPKNOT STARTER CASE HOLE 8. Pass the starter rope end through the starter case and pull it outwards. 9. Pass the starter rope through the starter handle. Tie the rope so that it can be untied easily by pulling it as shown.
  • Page 63 RECOIL STARTER / FUEL TANK HHT25S•HHT35S 4. HHT35S FUEL TANK REMOVAL\INSTALLATION  CUTAWAY VIEW OF A LOW-PERMEABILITY FUEL WARNING TANK (See page 1-2 for serial numbers) Gasoline is highly flammable and explosive. OUTSIDE You can be burned or seriously injured when handling 1 mm fuel.
  • Page 64: Table Of Contents

    2. HHT25S FAN COVER ............3. HHT25S IGNITION COIL/CLUTCH SHOE/FLYWHEEL ........
  • Page 65: Hht25S Starter Pulley

    STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL HHT25S•HHT35S 1. HHT25S STARTER PULLEY DISASSEMBLY/REASSEMBLY 1. Remove the top cover 4-1). 2. Remove the recoil starter 6-1). NOTICE To avoid flywheel fan blade damage, position the strap wrench fulcrum at the flywheel magnet.
  • Page 66: Hht25S Fan Cover

    HHT25S•HHT35S STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL 2. HHT25S FAN COVER REMOVAL/INSTALLATION 1. Remove the top cover 4-1). 2. Remove the frame pipe assembly 11-1). 3. Remove the 4 mm nylon lock nut. 4. Remove the three 5 x 20 socket bolts/washers, and remove the fan cover assembly.
  • Page 67 STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL HHT25S•HHT35S DISASSEMBLY 1. Turn the fan cover assembly over and insert a flat-blade screwdriver into the clamping collar gap. Carefully spread the gap slightly, and remove the pipe cap. 2. Remove the external circlip from the clutch outer shaft.
  • Page 68 HHT25S•HHT35S STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL REASSEMBLY 1. Secure the radial ball bearing inner race using a pipe or equivalent material of the following dimensions. Approx. 20 mm (0.8 in) or less Approx. 13 mm (0.5 in) or more Height: Approx.
  • Page 69: Hht25S Ignition Coil/Clutch Shoe/Flywheel

    STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL HHT25S•HHT35S 3. HHT25S IGNITION COIL/CLUTCH SHOE/FLYWHEEL IGNITION COIL DISASSEMBLY/REASSEMBLY INSPECTION: P. 7-8 ADJUSTMENT: P. 7-9 CLUTCH SHOE/FLYWHEEL DISASSEMBLY/REASSEMBLY DISASSEMBLY: P. 7-7 REASSEMBLY: P. 7-8 DISASSEMBLY: P. 7-7 REASSEMBLY: P. 7-7 INSPECTION: P. 7-8...
  • Page 70 HHT25S•HHT35S STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL CLUTCH ASSEMBLY NOTICE To avoid flywheel fan blade damage, position the strap wrench fulcrum at the flywheel magnetic parts. DISASSEMBLY Holding the flywheel with a commercially available strap wrench, remove the clutch bolt and remove the clutch assembly.
  • Page 71 STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL HHT25S•HHT35S REASSEMBLY Clean any dirt, oil, grease, or other foreign material from the crankshaft taper before installation. 1. Be sure that the woodruff key is set in the key groove properly, and install the flywheel.
  • Page 72 HHT25S•HHT35S STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL IGNITION COIL AIR GAP ADJUSTMENT Adjustment is required only when the ignition coil or the flywheel has been removed. 1. Loosen the ignition coil bolts, and insert a feeler gauge between the ignition coil and the magnetic parts of the flywheel.
  • Page 73: Hht35S Starter Pulley

    STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL HHT25S•HHT35S 4. HHT35S STARTER PULLEY ENGINE ASSEMBLY a. DISASSEMBLY & REASSEMBLY 1. Loosen the 5 mm top cover bolt, then remove the cover. 2. Remove the recoil starter 6-5. 3. Remove the fuel tank 6-8.
  • Page 74: Hht35S Clutch Housing Assembly

    HHT25S•HHT35S STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL 5. HHT35S CLUTCH HOUSING ASSEMBLY REMOVAL/INSTALLATION Remove the pipe assembly 11-4. CLUTCH HOUSING ASSEMBLY 6 x 25 mm SOCKET BOLT (4) 6.9 N•m (0.7 kg•m, 61 in•lb) DISASSEMBLY CLUTCH OUTER CLUTCH OUTER BEARING (6202ZZ)
  • Page 75: Hht35S Ignition Coil / Clutch Shoe / Flywheel

    STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL HHT25S•HHT35S 6. HHT35S IGNITION COIL / CLUTCH SHOE / FLYWHEEL IGNITION COIL DISASSEMBLY/ HIGH TENSION CORD REASSEMBLY REASSEMBLY: • Attach the plug cap in the direction as shown in the figure. • Attach the high tension...
  • Page 76 HHT25S•HHT35S STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL CLUTCH ASSEMBLY STRAP WRENCH (commercially available) DISASSEMBLY Hold the flywheel with a commercially available strap wrench, and remove the 8 mm clutch bolts, clutch washers, and clutch assembly. NOTICE To avoid flywheel fan blade damage, position the strap wrench fulcrum at the FULCRUM flywheel magnetic parts.
  • Page 77 STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL HHT25S•HHT35S REASSEMBLY STRAP WRENCH 1. Clean the tapered part of dirt, oil, grease, and other foreign material (commercially available) before installation. 2. Be sure the woodruff key is set in the key groove properly.
  • Page 78 HHT25S•HHT35S STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL IGNITION COIL AIR GAP ADJUSTMENT Adjustment is required only when the ignition coil or the flywheel has been removed. 1. Loosen the ignition coil bolts. 2. Insert a feeler gauge between the ignition coil and the magnetic part of the flywheel.
  • Page 79 STARTER PULLEY/ CLUTCH / IGNITION COIL / FLYWHEEL HHT25S•HHT35S 7-16...
  • Page 80 1. HHT25S CAM PULLEY/HEAD COVER..3. HHT35S CAM PULLEY/HEAD COVER . . 2. HHT25S LOWER CRANKCASE ... . 4. HHT35S LOWER CRANKCASE ..
  • Page 81 CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE HHT25S•HHT35S CAM PULLEY REMOVAL 1. Remove the spark plug and the head cover 3-11, 8-1). 2. Set the piston at top dead center (TDC) of the compression stroke. When the piston is at TDC of the compression stroke, the flywheel alignment mark “”...
  • Page 82 HHT25S•HHT35S CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE CYLINDER HEAD INNER COVER INSPECTION OIL PASSAGE Check the oil return passages of the cylinder head inner cover for restrictions. If they are restricted, clean with compressed air.
  • Page 83 CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE HHT25S•HHT35S 2. HHT25S LOWER CRANKCASE DISASSEMBLY/REASSEMBLY 1. Drain the engine oil 3-2). 2. Remove the air cleaner case assembly and carburetor 5-1, 5-2). 3. Remove the fuel tank protector, fuel tank and recoil starter 6-4).
  • Page 84 HHT25S•HHT35S CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE LOWER CRANKCASE REMOVAL 1. Remove the two 5 x 20 mm and four 5 x 30 mm hex bolts. 2. Insert a screwdriver or equivalent tool into the recess as shown, and remove the lower crankcase from the cylinder block.
  • Page 85 CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE HHT25S•HHT35S 4. Loosely tighten the two 5 x 20 mm and four 5 x 30 mm hex bolts, and then tighten in the numbered sequence. TORQUE: 6.4 N•m (5.1 ft•lb) 5. Wait for approximately 60 minutes after assembly before filling with oil and starting the engine.
  • Page 86 HHT25S•HHT35S CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE 3. HHT35S CAM PULLEY/HEAD COVER DISASSEMBLY/REASSEMBLY 1. Remove the top cover 4-2). 2. Remove the recoil starter 6-5). 3. Remove the fuel tank and protector 6-8). INSPECTION: P. 8-3 INSPECTION: P.
  • Page 87 CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE HHT25S•HHT35S CAM PULLEY REMOVAL 1. Remove the spark plug and the head cover 3-11, 8-7). 2. Set the piston at top dead center (TDC) of the compression stroke. When the piston is at TDC of the compression stroke, the flywheel alignment mark “”...
  • Page 88 HHT25S•HHT35S CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE CYLINDER HEAD INNER COVER INSPECTION OIL PASSAGE Check the oil return passages of the cylinder head inner cover for restrictions. If they are restricted, clean with compressed air.
  • Page 89 CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE HHT25S•HHT35S 4. HHT35S LOWER CRANKCASE DISASSEMBLY/REASSEMBLY 1. Drain the engine oil 3-2). 2. Remove the air cleaner case assembly and carburetor 5-6, 5-7). 3. Remove the fuel tank protector, fuel tank and recoil starter 6-5, 6-8).
  • Page 90 HHT25S•HHT35S CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE LOWER CRANKCASE REMOVAL 1. Remove the two 5 x 20 mm and four 5 x 30 mm hex bolts. 2. Insert a screwdriver or equivalent tool into the recess as shown, and remove the lower crankcase from the cylinder block.
  • Page 91 CAM PULLEY / CYLINDER HEAD COVER / LOWER CRANKCASE HHT25S•HHT35S 4. Loosely tighten the two 5 x 20 mm and four 5 x 30 mm hex bolts, and then tighten in the numbered sequence. TORQUE: 6.4 N•m (5.1 ft•lb) 5. Wait for approximately 60 minutes after assembly before filling with oil and starting the engine.
  • Page 92 9. CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK 1. CRANKSHAFT / PISTON ....3. INSPECTION ......2.
  • Page 93 CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK HHT25S•HHT35S PISTON PIN TIMING BELT DISASSEMBLY DRIVE 1. Insert the push rod special tool into the piston pin with the PULLEY crankshaft timing belt drive pulley upward as shown. TOOLS: TOOL: Push rod...
  • Page 94 HHT25S•HHT35S CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK 3. After centering the piston pin and special tools in the piston pin bore, remove the piston pin/tool assembly from the piston. 4. Set the piston over the connecting rod so that the crankshaft oil “Δ”...
  • Page 95 CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK HHT25S•HHT35S CRANKSHAFT OIL SLINGER INSPECTION Check the oil slinger of the crankshaft for damage and deformation. Replace the crankshaft if it is damaged or deformed OIL SLINGER REASSEMBLY 1. Install the timing belt on the timing gear of the crankshaft.
  • Page 96 HHT25S•HHT35S CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK 2. CYLINDER BLOCK / VALVES DISASSEMBLY & REASSEMBLY 1. Remove the cylinder head cover and cam pulley (P. 8-1, P. 8-7). 2. Remove the lower crankcase 8-5, 8-11). 3. Remove the crankshaft 9-1).
  • Page 97 CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK HHT25S•HHT35S 3. INSPECTION CYLINDER SLEEVE I.D. Measure and record the cylinder I.D. at three levels in both the “ X ” axis (perpendicular to crankshaft) and the “ Y ” axis (parallel to crankshaft).
  • Page 98 HHT25S•HHT35S CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK PISTON RING SIDE CLEARANCE Standard Service limit 0.0150 ~ 0.0560 mm 0.1200 mm Top/Second (0.0006 ~ 0.0022 in) (0.0047 in) When any piston ring exceeds the service limit, replace all the piston rings as a set.
  • Page 99 CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK HHT25S•HHT35S CONNECTING ROD SMALL END I.D. Standard Service limit 7.978 ~ 7.989 mm Replace if exceeding the (0.3141 ~ 0.3145 in) standard value CAM HEIGHT Standard Service limit 22.097 mm 21.797 mm HHT25S (0.8700 in)
  • Page 100 HHT25S•HHT35S CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK VALVE SPRING FREE LENGTH Measure the free length of the valve spring. Standard Service limit HHT25S 20.66 mm (0.8134 in) 20.00 mm (0.7874 in) HHT35S 21.77 mm (0.8570 in) 21.00 mm (0.8268 in) VALVE FACE/STEM O.D.
  • Page 101 CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK HHT25S•HHT35S COMBUSTION CHAMBER CLEANING 1. Prepare a cylinder of thick paper or equivalent material, with a ELECTRIC CLEANING BRUSH diameter large enough to fit against the inner wall of the cylinder, DRILL (commercially and insert it into the cylinder for protection.
  • Page 102 HHT25S•HHT35S CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK 4. ROCKER ARM/VALVE LIFTER REMOVAL 1. Remove the adjusting screw lock nuts [1] and remove the adjusting screws [2] from the rocker arms [3]. Remove the cam pulley (P. 8-1 8-7).
  • Page 103 CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK HHT25S•HHT35S INSTALLATION Viewing cylinder head right down: 1. Install the new valve lifter [1] on the cylinder head and bring the valve lifter in contact with the installation guide rib [2] of the cylinder head.
  • Page 104 HHT25S•HHT35S CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK 3. Install the holder bolt [1] of the special tool in the direction as shown. TOOL: Rocker arm replacement tool [2] 070PF-Z0HA100 Install the adapter [3] on the tip of the push rod [4] that is set on the special tool.
  • Page 105 CRANKSHAFT / PISTON / VALVES / CYLINDER BLOCK HHT25S•HHT35S 6. Loosen the push rod [1] and tighten the holder bolt [2] by hand until the valve lifter [3] contacts the cylinder head cover mounting boss [4]. Be sure that the bolt (5 mm) [5] is in the center of the long hole in the special tool.
  • Page 106 10. CUTTING ATTACHMENT / GEAR CASE 1. BLADE CUTTING ATTACHMENT ..4. SEMI-MATIC (BUMP-FEED) CUTTING-LINE 10-1 2. CUTTING-LINE HEADS....10-3 HEAD .
  • Page 107 CUTTING ATTACHMENT / GEAR CASE HHT25S•HHT35S DISASSEMBLY/REASSEMBLY 5 x 28 BOLT/WASHER (4) 5 x 28 mm BOLT/WASHER (4) 10 x 1.25 mm LOCK NUT (left-hand thread) TORQUE: TORQUE: 3.0 N•m (27 in•lbs) 3.0 N•m (0.30 kg•m, 27 in•lb) SPACER (2) TORQUE: 2.3 mm (3/32 in) thick...
  • Page 108 HHT25S•HHT35S CUTTING ATTACHMENT / GEAR CASE 2. CUTTING-LINE HEADS DISASSEMBLY/REASSEMBLY KWIK LOADER® CUTTING-LINE HEAD 5 x 28 mm REMOVAL/INSTALLATION: BOLT/WASHER (4) 5 x 12 mm P. 10-7 SELF-TAPPING SCREW TORQUE: CUTTING LINE REPLACEMENT: 3.0 N•m (0.30 kg•m, 27 in•lb) P. 10-7 TORQUE: 3.0 N•m (0.30 kg•m, 27 in•lb)
  • Page 109 CUTTING ATTACHMENT / GEAR CASE HHT25S•HHT35S CUTTING LINE HEAD REMOVAL Move the ignition switch to the STOP position, and disconnect the spark plug cap from the spark plug. Wear protective gloves during this procedure. HOLE 1. Align the gear case hole with the groove in the cover plate/ spacer A as shown, 2.
  • Page 110 HHT25S•HHT35S CUTTING ATTACHMENT / GEAR CASE 3. MANUAL-FEED CUTTING LINE HEAD DISASSEMBLY/REASSEMBLY KNOB, 5/16-18 LHF THREAD NYLON LINE REPLACEMENT: P. 3-5 REPLACEMENT: Always use 0.095 in or 0.105 in diameter nylon monofilament cutting line. SPRING SPOOL METAL EYELET (2) HOUSING SHAFT, 5/16 in MALE and 10 x 1.25 mm LEFT HAND...
  • Page 111 CUTTING ATTACHMENT / GEAR CASE HHT25S•HHT35S 4. SEMI-MATIC (BUMP-FEED) CUTTING-LINE HEAD DISASSEMBLY/REASSEMBLY NYLON LINE REPLACEMENT: P. 3-7 WASHER Always use 0.095 in or 0.105 in diameter nylon monofilament cutting line. SPRING SPOOL HOUSING INNER CAM OUTER DRIVE SHAFT, 5/16 in MALE and 10 x 1.25 mm LEFT HAND...
  • Page 112 HHT25S•HHT35S CUTTING ATTACHMENT / GEAR CASE 5. KWIK LOADER HEAD REMOVAL/INSTALLATION THREADED 1. Align the gear case hole with the groove in the cover plate/ COLLAR spacer A. 2. Insert a 4 mm hex tool or equivalent. CUTTING LINE 3. Hold the hex tool and turn the cutting-line head by hand in the direction of the arrow.
  • Page 113 CUTTING ATTACHMENT / GEAR CASE HHT25S•HHT35S 6. GEAR CASE REMOVAL 5 x 12 mm 1. Clean around the gear case area before starting work to BOLT/WASHER FRAME PIPE prevent dirt from entering the drive cable and bushing area. 2.5 N•m (0.25 kg•m, 22 in•lb)
  • Page 114 HHT25S•HHT35S CUTTING ATTACHMENT / GEAR CASE DISASSEMBLY/REASSEMBLY Use a heat gun or submerge the entire gear case in a pan of oil. Heat the oil to 80°C ~ 90°C (176°F ~ 194°F). When the entire gear case becomes hot, remove the gear case from the oil and disassemble. For reassembly, reverse the procedure and fill the gear case with the NLGI #2 grease.
  • Page 115 CUTTING ATTACHMENT / GEAR CASE HHT25S•HHT35S 10-10...
  • Page 116 11. FRAME ASSEMBLY / HANDLEBAR 1. HHT25S FRAME PIPE ASSEMBLY ..4. LOOP HANDLE/THROTTLE TRIGGER . . . 11-1 11-10 2. HHT35S FRAME PIPE ASSEMBLY ..5. DRIVE CABLE/BUSHING/FRAME PIPE. . .
  • Page 117 FRAME ASSEMBLY / HANDLEBAR HHT25S•HHT35S INSTALLATION Installation is done in the reverse order of removal. 1. Insert the frame pipe cap into the fan cover assembly. Make sure the cap is seated at the bottom of the fan cover. 2. Install the tolerance ring into the fan cover assembly with the gap located opposite the clamping bolt, and the ring seated against the lip in the fan cover.
  • Page 118 HHT25S•HHT35S FRAME ASSEMBLY / HANDLEBAR 7. Connect the ignition switch connector. Install the 5 x 10 mm socket bolt, and reconnect the ground cable. 8. Connect the throttle cable to the swivel and adjust the throttle cable free play 3-4).
  • Page 119 FRAME ASSEMBLY / HANDLEBAR HHT25S•HHT35S SERVICE BULLETIN #4 => 2. HHT35S FRAME PIPE ASSEMBLY SWIVEL  CAUTION THROTTLE Remove the spark plug cap, and install the CABLE blade cover over the blade cutter before removal/installation of the frame pipe assembly.
  • Page 120 HHT25S•HHT35S FRAME ASSEMBLY / HANDLEBAR 5. Set the throttle cable lock nut and adjust nut at the ends of the threads as shown. CABLE LOCK NUT ADJUST NUT THREADS THROTTLE CABLE 6. Install the throttle cable end from the round hole side in the THROTTLE swivel of the carburetor throttle.
  • Page 121 FRAME ASSEMBLY / HANDLEBAR HHT25S•HHT35S 3. U-TYPE HANDLE/THROTTLE TRIGGER DISASSEMBLY/REASSEMBLY Disconnect the throttle cable, ignition switch connector, and the ground cable. It is necessary to remove the frame pipe assembly from the engine in order to remove/install hanger holders A and B.
  • Page 122 HHT25S•HHT35S FRAME ASSEMBLY / HANDLEBAR THROTTLE TRIGGER SPRING/THROTTLE HOOK TRIGGER INSTALLATION 1. Set the throttle trigger spring on the throttle trigger as shown. Pass the hook of the throttle trigger spring through the hole in the throttle trigger. THROTTLE TRIGGER...
  • Page 123 FRAME ASSEMBLY / HANDLEBAR HHT25S•HHT35S IGNITION SWITCH/THROTTLE CABLE IGNITION IGNITION SWITCH INSTALLATION SWITCH WIRE 1. Install the ignition switch on the L. throttle trigger grip as shown, GROOVE and set the ignition switch wire in the groove and between the pin and grip case.
  • Page 124 HHT25S•HHT35S FRAME ASSEMBLY / HANDLEBAR 4. Adjust the handlebar so that it makes a right angle with the frame pipe center line as viewed from the gear case. 5. After adjustment, secure handlebar holder C by tightening the FRAME PIPE two 5 x 25 mm flange bolts to the specified torque.
  • Page 125 FRAME ASSEMBLY / HANDLEBAR HHT25S•HHT35S 4. LOOP HANDLE/THROTTLE TRIGGER DISASSEAMBLY/REASSEMBLY Disconnect the throttle cable, ignition switch connector, and the ground cable. You must remove the frame pipe assembly from the engine in order to remove/install hanger holders A and B P.
  • Page 126 See 11-7. HHT25S LOOP HANDLE/THROTTLE TRIGGER GRIP INSTALLATION Adjust the handle position shown in step 2 and the throttle trigger grip position shown in step 4 with the frame pipe assembly removed from the engine.
  • Page 127 FRAME ASSEMBLY / HANDLEBAR HHT25S•HHT35S HHT35S LOOP HANDLE / L. / R. THROTTLE TRIGGER GRIP INSTALLATION 81.5 mm LOOP HANDLE (3.2 in) Adjust the handle position shown in step 2 and the throttle trigger grip position shown in step 3 with the frame pipe assembly removed from the engine.
  • Page 128 HHT25S•HHT35S FRAME ASSEMBLY / HANDLEBAR IGNITION SWITCH INSPECTION Check for continuity between the switch connector and ground terminal. There should be continuity with the ignition switch in the STOP position, and no continuity with the ignition switch in the ON position.
  • Page 129 FRAME ASSEMBLY / HANDLEBAR HHT25S•HHT35S 5. DRIVE CABLE/BUSHING/FRAME DRIVE PIPE CABLE DISASSEMBLY 1. Clean around the frame pipe at the gear case end and engine end before starting work to prevent dirt from entering the drive cable and bushing area.
  • Page 130 Dimensional drawings HHT25S ........5-1 HHT25S .
  • Page 131 Specifications HHT25S ........8-4 Dimensions........1-1 HHT35S .

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