Yamaha MX360 Service Manual
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Yamaha MX360 Service Manual

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SERVICE MANUAL
MX360
7HC-F8197-E0

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  • Page 1 SERVICE MANUAL MX360 7HC-F8197-E0...
  • Page 3 FOREWORD HOW TO USE THIS MANUAL PARTICULARLY IMPORTANT This manual was written by the Yamaha Motor Powered Products Co., Ltd. primarily for use INFORMATION by Yamaha dealers and their qualified mechan- ics. It is not possible to put an entire mechan- Particularly important information is distin- ic’s education into one manual, so it is...
  • Page 4 HOW TO USE THIS MANUAL This Service Manual contains general information on service procedure and data for the Multi- purpose engine. For complete information on service procedure and data, it is necessary to use this Service Manual together with the Supplementary Service Manual. Comprehensive explanations of all installation, removal, disassembly, assembly, repair and check procedures are laid out with the individual steps in sequential order.
  • Page 5 ILLUSTRATED SYMBOLS (Refer to the illustration) SYMBOL DEFINITION SYMBOL DEFINITION Periodic checks and General information adjustments Engine Carburetor Electrical Troubleshooting Specifications Filling fluid Lubricant Special tool Tightening torque Wear limit, clearance Engine speed Electrical data Replace the part with a new one. Lithium-soap base grease Molybdenum disulfide grease Engine oil...
  • Page 7 INDEX GENERAL INFORMATION INFO PERIODIC CHECKS AND ADJUSTMENTS ENGINE CARBURETOR CARB ELECTRICAL ELEC TROUBLESHOOTING TRBL...

  • Page 8: Table Of Contents

    CHAPTER 1. RECOIL STARTER ......2-17 FITTINGS AND FASTENERS ....2-17 GENERAL INFORMATION CHAPTER 3. IMPORTANT INFORMATION ....1-1 ENGINE PREPARATION FOR REMOVAL AND DISASSEMBLY CAUTION ON ENGINE INSPECTION .......3-1 SERVICE ..........1-1 MEASURING THE COMPRESSION NOTES ON SERVICE......1-1 PRESSURE ..........3-1 ALL REPLACEMENT PARTS ....1-2 GASKETS, OIL SEALS, AND AIR FILTER ..........3-3 O-RINGS ..........1-2...
  • Page 9 ENGINE SWITCH AND OIL WARNING SELECTING THE CRANKSHAFT UNIT ............3-19 SHIM ...........3-47 CYLINDER HEAD COVER, CYLINDER CHAPTER 4. HEAD ............3-20 CARBURETOR CHECKING THE ROCKER ARM ..3-22 CHECKING THE PUSH ROD .....3-22 REMOVING THE CARBURETOR ....4-1 CHECKING THE CYLINDER HEAD ..........3-22 DISASSEMBLING THE CARBURETOR ...4-2 INSTALLING THE CYLINDER CHECKING THE CARBURETOR ..4-3...

  • Page 10: General Information

    Be sure to use the correct special tool for the job to guard against damage. SVU1040 2. Oil, grease and seals Be sure to use genuine Yamaha oils, grease and sealers, or the equivalents. SVU1050 3. Expendable parts Always replace the gaskets, O-rings, cotter pins and circlips with new parts when servicing engine.

  • Page 11: All Replacement Parts

    IMPORTANT INFORMATION INFO ALL REPLACEMENT PARTS We recommend the use of genuine Yamaha parts for all replace- ments. Use oil and/or grease, recommended by Yamaha, for assembly and adjustment. GASKETS, OIL SEALS, AND O-RINGS 1. All gaskets, seals, and O-rings should be replaced when an engine is overhauled.

  • Page 12: Basic Service Information

    BASIC SERVICE INFORMATION INFO BASIC SERVICE INFORMATION ELECTRICAL SYSTEM Checking the electrical system Before checking the electrical system, make sure that the battery voltage is at least 12 V. NOTICE Never insert the tester probes into the coupler terminal slots. Always insert the probes from the opposite end a of the cou- pler, taking care not to loosen or damage the leads.
  • Page 13 BASIC SERVICE INFORMATION INFO 2. Check: 9 Lead 9 Coupler 9 Connector Moisture → Dry with an air blower. Rust/stains → Connect and disconnect several times. 3. Check: 9 All connections Loose connection → Connect properly. 9 If the pin 1 on the terminal is flattened, bend it up. 9 After disassembling and assembling a coupler, pull on the leads to make sure that they are installed securely.
  • Page 14 BASIC SERVICE INFORMATION INFO 5. Check: 9 Continuity (with the pocket tester) Analog pocket tester: YU-03112-C Pocket tester: 90890-03112 9 If there is no continuity, clean the terminals. 9 When checking the wire harness, perform steps (1) to (4). 9 Make sure to check the connector and coupler of the TCI unit/ CDI unit when replacing the TCI unit/CDI unit.

  • Page 15: Special Tools And Testers

    SPECIAL TOOLS AND TESTERS INFO SPECIAL TOOLS AND TESTERS The proper special tools are necessary for complete and accurate tune-up and assembly. Using the correct special tool will help pre- vent damage caused by the use of improper tools or improvised techniques.
  • Page 16 SPECIAL TOOLS AND TESTERS INFO 6. Extension P/N. 90890-04082 This tool is used for checking engine compression. 7. Primary clutch holder P/N. YS-01880-A Sheave holder P/N. 90890-01701 This tool is necessary for holding the magneto rotor. 8. Heavy duty puller P/N.

  • Page 17: Chapter 2. Periodic Checks And Adjustments

    INTRODUCTION/MAINTENANCE INTERVALS CHART/ PERIODIC MAINTENANCE/LUBRICATION INTERVALS PERIODIC CHECKS AND ADJUSTMENTS INTRODUCTION This chapter includes all information necessary to perform recommended checks and adjustments. These preventive maintenance procedures, if followed, will ensure more reliable machine opera- tion and a longer service life. The need for costly overhaul work will be greatly reduced. This infor- mation applies to machines already in service as well as new machines that are being prepared for sale.

  • Page 18: Periodic Maintenance/Lubrication Intervals

    *1····· The air filter element needs to be cleaned more frequently when using in unusually wet or dusty areas. ····· Since these items require special tools, data and technical skills, have a Yamaha dealer per- form the service.

  • Page 19: Periodic Maintenance

    PERIODIC MAINTENANCE PERIODIC MAINTENANCE SPARK PLUG WARNING Check and adjust the areas around the cyl- inder head after the engine has cooled down completely. 1. Remove: 9 Spark plug cap 9 Spark plug NOTICE Before removing the spark plug, use com- pressed air to clean the cylinder head cover to prevent dirt from falling into the engine.
  • Page 20 PERIODIC MAINTENANCE Feeler gauge set: YU-26900-9 Thickness gauge: 90890-03180 Spark plug gap: Refer to “SPECIFICATIONS” in the Supplementary service manual. Before installing the spark plug, clean the gas- ket surface and plug surface. 4. Install: 9 Spark plug Spark plug: Refer to “TIGHTENING TORQUES”...

  • Page 21: Fuel Leakage

    PERIODIC MAINTENANCE FUEL LEAKAGE 1. Check: 9 Leakage Check at fuel tank, fuel cock, fuel hose, and carburetor. NOTICE Replace fuel hose every four years. ENGINE OIL LEAKAGE 1. Place the multi-purpose engine on a level surface. 2. Check the areas outside of the engine for oil leakage.

  • Page 22: Replacing The Engine Oil

    PERIODIC MAINTENANCE REPLACING THE ENGINE OIL 1. Warm up the engine for several minutes, and then stop the engine. 2. Remove: 9 Oil filler cap 1 9 Oil drain bolt 2 9 Oil drain bolt gasket 3 9 This engine is equipped with two oil filler caps.

  • Page 23: Air Filter Element

    PERIODIC MAINTENANCE AIR FILTER ELEMENT NOTICE Be sure not to run the engine without air filter element. Otherwise this can result in excessive piston and/or cylinder wear. 1. Remove: 9 Air filter cover nut 1 9 Air filter cover 2 9 Air filter element nut 3 2.

  • Page 24: Muffler

    PERIODIC MAINTENANCE MUFFLER WARNING The engine and muffler will be very hot after the engine has been run. Avoid touching the engine and muffler while they are still hot with any part of your body or clothing during check or repair.

  • Page 25: Fuel Tank Filter

    PERIODIC MAINTENANCE 5. Decarbonize: 9 Spark arrester NOTICE When cleaning with a wire brush, use it softly to avoid damage or scratch the spark arrester. 6. Install: 9 Muffler (Refer “INSTALLING MUFFLER” on 3-7) 9 Spark arrester 9 Spark arrester screw Spark arrester screw: Refer to “TIGHTENING TORQUES”...

  • Page 26: Fuel Cock Strainer

    PERIODIC MAINTENANCE 3. Install: 9 Fuel tank filter 9 Fuel tank cap WARNING Make sure that the tank cap is tightened securely. FUEL COCK STRAINER WARNING Do not smoke, and keep away from open flames, sparks, or any other source of fire when handling or in the vicinity of fuel.

  • Page 27: Breather Hose

    PERIODIC MAINTENANCE 4. Install: 9 Fuel cock strainer 9 Gasket 9 Strainer cup Strainer cup: Refer to “TIGHTENING TORQUES” in the Supplementary service manual. WARNING Make sure that the strainer cup is tight- ened securely. BREATHER HOSE 1. Check: 9 Breather hose 1 Crack/damage →...

  • Page 28: Adjusting The Valve Clearance

    PERIODIC MAINTENANCE ADJUSTING THE VALVE CLEARANCE 1. Remove: 9 Spark plug cap 1 9 Spark plug 2 NOTICE Before removing the spark plug, use com- pressed air to clean the cylinder head cover to prevent dirt from falling into the engine.
  • Page 29 PERIODIC MAINTENANCE Valve clearance (cold): Refer to “SPECIFICATIONS” in the Supplementary service manual. 5. Adjust: 9 Valve clearance Adjustment steps: a. Loosen the locknut 1 and insert the 0.07 mm (0.0028 in) thickness gauge between the rocker arm and the valve tip.

  • Page 30: Engine Speed (Without Throttle Lever Model)

    PERIODIC MAINTENANCE 6. Install: 9 Cylinder head cover gasket 9 Cylinder head cover 9 Air filter case stay Cylinder head cover bolt: Refer to “TIGHTENING TORQUES” in the Supplementary service manual. 9 Breather hose 9 Spark plug Spark plug: Refer to “TIGHTENING TORQUES” in the Supplementary service manual.

  • Page 31: Engine Speed (With Throttle Lever Model)

    PERIODIC MAINTENANCE ENGINE SPEED (WITH THROTTLE LEVER MODEL) 1. Warm up the engine for several minutes. 2. Attach: 9 Digital tachometer 1 Digital tachometer: YU-39951-B, 90890-06760 3. Measure: 9 High engine speed (with no load) Out of specification → Adjust. High engine speed: Refer to “SPECIFICATIONS”...

  • Page 32: Adjusting The Engine Speed

    PERIODIC MAINTENANCE ADJUSTING THE ENGINE SPEED 1. Warm up the engine for several minutes. 2. Attach: 9 Digital tachometer 1 Digital tachometer: YU-39951-B, 90890-06760 3. Adjust: 9 Engine speed Adjustment steps: a. Loosen the throttle stop screw 1. b. Move the throttle lever 2 to direction a or b until the high engine speed is obtained.

  • Page 33: Recoil Starter

    PERIODIC MAINTENANCE RECOIL STARTER 1. Check: 9 Recoil starter operate smoothly Rough movement → Replace the defective part(s). (Refer to “CHECKING THE RECOIL STARTER” on 3-10) FITTINGS AND FASTENERS 1. Check: 9 All fittings and fasteners Looseness → Tighten. Rough movement → Replace the defective part(s).

  • Page 34: Chapter 3. Engine

    CHAPTER 3. ENGINE INSPECTION ENGINE ENGINE INSPECTION MEASURING THE COMPRESSION PRESSURE Measure the compression pressure after checking and adjusting the valve clearance. 1. Warm up the engine for several minutes. 2. Remove: 9 Spark plug cap 9 Spark plug NOTICE Before removing the spark plug, use com- pressed air to clean the cylinder head cover to prevent dirt from falling into the...
  • Page 35 ENGINE INSPECTION 4. Measure: 9 Compression pressure Crank the engine until the needle stop rising on the compression gauge. Out of specification → Refer to the testing steps. Standard compression pressure: Refer to “SPECIFICATIONS” in the Supplementary service manual. WARNING To prevent sparking when cranking the engine, ground the high tension cord.

  • Page 36: Air Filter

    AIR FILTER AIR FILTER 1.6 Nm (0.16 m · kgf, 1.2 ft · lbf) 0.9 Nm (0.09 m · kgf, 0.65 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) 15 Nm (1.5 m · kgf, 11 ft · lbf) Order Job/Parts to remove Q’ty...

  • Page 37: Fuel Tank

    FUEL TANK FUEL TANK Except for MX360A46A5/MX360C46A5 10 Nm (1.0 m · kgf, 7.2 ft · lbf) 10 Nm (1.0 m · kgf, 7.2 ft · lbf) 29 Nm (2.9 m · kgf, 21 ft · lbf) 6 Nm (0.6 m · kgf, 4.3 ft · lbf) 0.8 Nm (0.08 m ·...

  • Page 38: Mx360A46A5/Mx360C46A5

    FUEL TANK MX360A46A5/MX360C46A5 10 Nm (1.0 m · kgf, 7.2 ft · lbf) 10 Nm (1.0 m · kgf, 7.2 ft · lbf) 29 Nm (2.9 m · kgf, 21 ft · lbf) 29 Nm (2.9 m · kgf, 21 ft · lbf) 1.3 Nm (0.13 m ·...

  • Page 39: Muffler

    MUFFLER MUFFLER 10 Nm (1.0 m · kgf, 7.2 ft · lbf) 10 Nm (1.0 m · kgf, 7.2 ft · lbf) 3.5 Nm (0.35 m · kgf, 2.5 ft · lbf) 20 Nm (2.0 m · kgf, 14 ft · lbf) 20 Nm (2.0 m ·...

  • Page 40: Installing The Muffler

    MUFFLER INSTALLING THE MUFFLER 1. Install: 9 Gasket 9 Muffler assembly 9 Muffler nut 1 9 Muffler nut 2 9 Muffler bolt 3 Temporarily tighten the nut 1, nut 2, and bolt 3 until just comes in contact with the surface. 2.

  • Page 41: Recoil Starter

    RECOIL STARTER RECOIL STARTER 5.4 Nm (0.54 m · kgf, 3.9 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) Order Job/Parts to remove Q’ty Remarks Removing the recoil starter Remove the parts in the order listed. Recoil starter assembly Starter handle Drive plate...

  • Page 42: Disassembling The Recoil Starter

    RECOIL STARTER DISASSEMBLING THE RECOIL STARTER 1. Remove: 9 Starter handle 1 Before untying the knot a above the starter handle, make a knot b on the rope so that the rope is not pulled into the case. 2. Remove: 9 Drive plate screw 1 9 Drive plate/Clip 9 Drive pawls...

  • Page 43: Checking The Recoil Starter

    RECOIL STARTER CHECKING THE RECOIL STARTER 1. Check: 9 Starter rope Wear/damage → Replace. 9 Starter case Cracks/damage → Replace. 9 Starter spring Dirt → Clean and apply grease. Wear/damage → Replace. 2. Check: 9 Drive pawls 1 9 Drive plate 2 Wear/damage →...
  • Page 44 RECOIL STARTER 4. Install: 9 Compression spring 1 9 Drive plate/Clip 2 5. Install: 9 Starter handle 9 Drive plate screw 1 To set the spring preload, hook the starter rope into the sheave drum slot a and turn the sheave drum assembly counterclockwise four times, and then unhook the starter rope from the slot.

  • Page 45: Flywheel

    FLYWHEEL FLYWHEEL 10 Nm (1.0 m · kgf, 7.2 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) 120 Nm (12 m · kgf, 87 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) 7 Nm (0.7 m ·...

  • Page 46: Removing The Flywheel

    FLYWHEEL REMOVING THE FLYWHEEL 1. Remove: 9 Flywheel cover 9 TCI unit 2. Remove: 9 Flywheel nut 1 9 Washer 9 Starter pulley Attach the sheave holder 2 to hold the fly- wheel. Primary clutch holder: YS-01880-A Sheave holder: 90890-01701 3.

  • Page 47: Installing The Flywheel

    FLYWHEEL INSTALLING THE FLYWHEEL 1. Install: 9 Woodruff key 9 Flywheel 2. Install: 9 Starter pulley 9 Washer 9 Flywheel nut 1 Flywheel nut: Refer to “TIGHTENING TORQUES” in the Supplementary service manual. Tighten the flywheel nut 1 using the sheave holder 2 to hold the flywheel.

  • Page 48: Installing The Tci Unit

    FLYWHEEL INSTALLING THE TCI UNIT 1. Install: 9 TCI unit 9 TCI unit bolts TCI unit bolt: Refer to “TIGHTENING TORQUES” in the Supplementary service manual. 2. Measure: 9 TCI unit air gap Out of specification → Adjust. Feeler gauge set: YU-26900-9 Thickness gauge: 90890-03180...

  • Page 49: Governor

    GOVERNOR GOVERNOR Order Job/Parts to remove Q’ty Remarks Removing the governor Remove the parts in the order listed. Fuel tank Refer to “FUEL TANK” on 3-4. Fuel tank stay Refer to “FUEL TANK” on 3-4. Engine switch and oil warning unit Refer to “ENGINE SWITCH AND OIL WARNING UNIT”...

  • Page 50: Checking The Flyweight Shaft Assembly And Governor Shaft

    GOVERNOR REMOVING THE FLYWEIGHT SHAFT ASSEMBLY AND GOVERNOR SHAFT 1. Remove: 9 Crankcase cover (Refer to “PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT” on 3-31) 9 Governor arm (Refer “GOVERNOR” Supplementary service manual) 2. Remove: 9 Clip 1 9 Governor shaft 2 9 Washers 3 3.

  • Page 51: Assembling The Flyweight Shaft Assembly

    GOVERNOR 2. Check: 9 Flyweight gear 9 Flyweight shaft 9 Collar 9 Washer 9 Governor shaft Wear/damage → Replace. ASSEMBLING THE FLYWEIGHT SHAFT ASSEMBLY 1. Install: 9 Flyweight shaft 1 9 Circlip 2 9 Washer 3 9 Collar 4 9 Weights 5 9 Weight shafts 6 INSTALLING THE FLYWEIGHT SHAFT ASSEMBLY AND GOVERNOR SHAFT...

  • Page 52: Engine Switch And Oil Warning Unit

    ENGINE SWITCH AND OIL WARNING UNIT ENGINE SWITCH AND OIL WARNING UNIT 0.7 Nm (0.07 m · kgf, 0.51 ft · lbf) 4.5 Nm (0.45 m · kgf, 3.3 ft · lbf) 4.5 Nm (0.45 m · kgf, 3.3 ft · lbf) Order Job/Parts to remove Q’ty...

  • Page 53: Cylinder Head Cover, Cylinder Head

    CYLINDER HEAD COVER, CYLINDER HEAD CYLINDER HEAD COVER, CYLINDER HEAD 11 Nm (1.1 m · kgf, 8.0 ft · lbf) 20 Nm (2.0 m · kgf, 14 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) 2.3 Nm (0.23 m ·...
  • Page 54 CYLINDER HEAD COVER, CYLINDER HEAD 11 Nm (1.1 m · kgf, 8.0 ft · lbf) 20 Nm (2.0 m · kgf, 14 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) 2.3 Nm (0.23 m · kgf, 1.7 ft · lbf) 12 Nm (1.2 m ·...

  • Page 55: Checking The Rocker Arm

    CYLINDER HEAD COVER, CYLINDER HEAD CHECKING THE ROCKER ARM 1. Check: 9 Rocker arm Wear/damage/cracks → Replace. CHECKING THE PUSH ROD 1. Check: 9 Push rod runout Runout limit: Refer to “SPECIFICATIONS” in the Supplementary service manual. Out of specifications → Replace. CHECKING THE CYLINDER HEAD 1.

  • Page 56: Installing The Cylinder Head Assembly

    CYLINDER HEAD COVER, CYLINDER HEAD 3. Measure: 9 Cylinder head warpage Measure the warpage on the contact surface of the cylinder head at six points using the straight edge and thickness gauge. Warpage limit: Refer to “SPECIFICATIONS” in the Supplementary service manual.

  • Page 57: Valve

    VALVE VALVE Order Job/Parts to remove Q’ty Remarks Removing the valve Remove the parts in the order listed. Cylinder head assembly Refer to “CYLINDER HEAD COVER, CYLINDER HEAD” on 3-20. Valve cotter Valve spring retainer Valve spring Exhaust valve Intake valve Valve stem seal Intake side only.

  • Page 58: Removing The Valve And Valve Spring

    VALVE REMOVING THE VALVE AND VALVE SPRING 1. Remove: 9 Valve cotters 1 9 Valve spring retainers 2 9 Valve springs 3 9 Valves 4 9 Valve stem seal (Intake side only) Remove the parts using the valve spring compressor 5. NOTICE Do not compress the valve spring more than necessary.
  • Page 59 VALVE 2. Measure: 9 Valve stem diameter a Valve stem diameter: Refer to “SPECIFICATIONS” in the Supplementary service manual. Limit: Refer to “SPECIFICATIONS” in 302-001 the Supplementary service manual. Out of specifications → Replace. 3. Measure: 9 Valve stem runout Valve stem runout limit: Refer to “SPECIFICATIONS”...

  • Page 60: Checking The Valve Seat

    VALVE 5. Measure: 9 Compressed valve spring force a 9 Installed length b Out of specification → Replace. Installed compression spring force: Refer to “SPECIFICATIONS” in the Supplementary service manual. Installed length: Refer to “SPECIFICATIONS” in the Supplementary service manual. 6.
  • Page 61 VALVE Do not rotate the valve while the valve face is contacting the valve seat. 4. Measure: 9 Valve face contact width a Make sure that the contact width along the entire valve face is within specifica- tions. Valve face contact width: Refer to “SPECIFICATIONS”...

  • Page 62: Valve Lapping

    VALVE 6. Remove carbon deposits on the valve face a and valve seat. 9 Valve seat width b 9 Valve margin thickness c Apply a small amount of coarse mechanic’s blueing dye (Dykem) to the valve seat. Press the valve through the valve guide and onto the valve seat to make a clear impression.

  • Page 63: Installing The Valve And Valve Spring

    VALVE NOTICE Do not let the lapping compound enter the gap between the valve stem and the valve guide. After every lapping procedure, clean off the compound from the valve face and valve seat. INSTALLING THE VALVE AND VALVE SPRING 1.

  • Page 64: Piston, Camshaft, Crankcase, And Crankshaft

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 27 Nm (2.7 m · kgf, 20 ft · lbf) 27 Nm (2.7 m · kgf, 20 ft · lbf) 10 Nm (1.0 m · kgf, 7.2 ft · lbf) 10 Nm (1.0 m ·...
  • Page 65 PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 20 Nm (2.0 m · kgf, 14 ft · lbf) Order Job/Parts to remove Q’ty Remarks Balancer shaft Camshaft Valve lifter Crankshaft shim — R e f e r “ S E L E C T I N G T H E CRANKSHAFT SHIM”...

  • Page 66: Removing The Balancer Shaft, Camshaft, And Valve Lifter

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT REMOVING THE BALANCER SHAFT, CAMSHAFT, AND VALVE LIFTER 1. Remove: 9 Balancer shaft 1 Remove the balancer shaft 1 when the bal- ancer shaft gear mark a and the crankshaft gear mark b are aligned. 2.
  • Page 67 PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 2. Check: 9 Camshaft lobe dimensions a and b Camshaft lobe dimensions: Dimension a: Refer to “SPECIFICATIONS” in the Supplementary service manual. Limit: Refer to “SPECIFICATIONS” in the Supplementary service manual. Dimension b: Refer to “SPECIFICATIONS” in the Supplementary service manual.

  • Page 68: Checking The Valve Lifter

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT CHECKING THE VALVE LIFTER 1. Check: 9 Valve lifter Damage → Replace. INSTALLING THE VALVE LIFTER, BALANCER SHAFT, AND CAMSHAFT 1. Install: 9 Intake valve lifter 1 9 Exhaust valve lifter 2 2. Install: 9 Balancer shaft 1 NOTICE Be sure to align the balancer shaft 1 gear mark a with the crankshaft gear mark b.

  • Page 69: Installing The Crankcase Cover

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT INSTALLING THE CRANKCASE COVER 1. Install: 9 Crankcase cover 9 Crankcase cover bolts 1 to 8 Tighten the bolts to the specified torque in two steps and in order from 1 to 8. Crankcase cover bolt: Refer to “TIGHTENING TORQUES”...

  • Page 70: Checking The Crankcase

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 2. Measure: 9 Cylinder warpage Measure the warpage on the contact surface of the cylinder head at six points using the straight edge and thickness gauge. Feeler gauge set: YU-26900-9 Thickness gauge: 90890-03180 Warpage limit: Refer to “SPECIFICATIONS”...

  • Page 71: Checking The Piston And Piston Pin

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT CHECKING THE PISTON AND PISTON PIN 1. Measure: 9 Piston skirt diameter P a = 10 mm (0.4 in) from the piston bottom edge Out of specification → Replace. Piston skirt diameter: Refer to “SPECIFICATIONS” in 307-001 the Supplementary service manual.
  • Page 72 PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 3. Measure: 9 Piston pin hole inside diameter a Out of specifications → Replace. Piston pin hole inside diameter: Refer to “SPECIFICATIONS” in the Supplementary service manual. Limit: Refer to “SPECIFICATIONS” in the Supplementary service manual.

  • Page 73: Measuring The Piston Ring

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 5. Check: 9 Check that the piston pin enters smoothly into the piston pin hole. If the piston pin fits too tight into the piston, check the piston pin hole. If there is any pro- trusion, use a knife or scraper to gently remove it so that piston pin can be pushed in smoothly with your fingers.

  • Page 74: Checking The Crankshaft

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 3. Measure: 9 Piston ring side clearance Out of specification → Replace the pis- ton and piston ring as a set. Use a thickness gauge 1. 9 Clean carbon deposits from the piston ring grooves and rings before measuring the side clearance.
  • Page 75 PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 2. Measure: 9 Crankshaft runout limit Out of specification → Replace. Use a dial gauge. Dial indicator gauge: YU-A8428 Dial gauge: 90890-03097 Runout limit: Refer to “SPECIFICATIONS” in the Supplementary service manual. 3. Measure: 9 Crank pin outside diameter a Out of specification →...

  • Page 76: Checking The Connecting Rod Oil Clearance

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT CHECKING THE CONNECTING ROD OIL CLEARANCE Measure the oil clearance if replacing the crankshaft or connecting rod. 1. Place a piece of Plastigauge 1 on the ® crank pin horizontally. Wipe off oil thoroughly from the crankshaft, connecting rod, and connecting rod cap.

  • Page 77: Installing The Piston And Piston Ring

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 3. Remove: 9 Connecting rod cap 9 Connecting rod 4. Measure: 9 Connecting rod big end oil clearance Out of specification → Replace crank- shaft or connecting rod assembly, and then measure the clearance again. Measure the widest portion of the pressed Plastigauge ®...

  • Page 78: Installing The Crankshaft

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 3. Install: 9 Piston 1 9 Piston pin 2 9 Piston pin circlips 3 9 Make sure that the “7HD” mark a on the connecting rod faces toward the crankcase cover. 9 Make sure that the “ ”...
  • Page 79 PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 3. Attach: 9 Piston ring compressor 1 Piston ring compressor: YM-08037, 90890-05158 Attach the piston ring compressor to the pis- ton, and then insert the piston into the cylin- der. 4. Check: 9 Piston with the connecting rod 1 posi- tion 9 Make sure that the “...

  • Page 80: Selecting The Crankshaft Shim

    PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 6. Install: 9 Connecting rod cap 1 9 Connecting rod cap bolts 2 Connecting rod cap bolt: Refer to “TIGHTENING TORQUES” in the Supplementary service manual. 9 Make sure that the “ ” mark a on the con- necting rod is aligned with the “...
  • Page 81 PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT 3. Adjust: 9 Crankshaft free play Adjustment steps: a. Remove the crankcase cover 1. (Refer to “PISTON, CAMSHAFT, CRANKCASE, AND CRANKSHAFT” on 3-31) b. Install or remove the shim 2 of the proper thickness. c. Install the crankcase cover 1. ( R e f e r t o “...

  • Page 82: Chapter 4. Carburetor

    CARB REMOVING THE CARBURETOR CARBURETOR REMOVING THE CARBURETOR Order Job/Parts to remove Q’ty Remarks Removing the carburetor Remove the parts in the order listed. Fuel tank Refer to “FUEL TANK” on 3-4. Air filter Refer to “AIR FILTER” on 3-3. Carburetor assembly Link rod Spring...

  • Page 83: Disassembling The Carburetor

    CARB DISASSEMBLING THE CARBURETOR DISASSEMBLING THE CARBURETOR 1.2 Nm (0.12 m · kgf, 0.87 ft · lbf) 0.7 Nm (0.07 m · kgf, 0.51 ft · lbf) 0.7 Nm (0.07 m · kgf, 0.51 ft · lbf) 7 Nm (0.7 m · kgf, 5.1 ft · lbf) 1.3 Nm (0.13 m ·...

  • Page 84: Checking The Carburetor

    CARB DISASSEMBLING THE CARBURETOR CHECKING THE CARBURETOR 1. Measure: 9 Float height a Out of specification → Replace. 9 Lift up the float so that the tip of the float valve lightly contacts the float arm, and then measure the float height a. 9 Do not adjust the float height.

  • Page 85: Chapter 5. Electrical

    ELEC ELECTRICAL COMPONENTS ELECTRICAL ELECTRICAL COMPONENTS 1 Spark plug 2 TCI unit 3 Oil warning unit (With oil warning model) 4 Engine switch 5 Oil level switch (With oil warning model) 6 Oil warning light (With oil warning model)

  • Page 86: Switches

    ELEC SWITCHES SWITCHES CHECKING THE SWITCH CONTINUITY Use a pocket tester to check the terminals for continuity. If a continuity error is found at any point, replace the switch. Analog pocket tester: YU-03112-C Pocket tester: 90890-03112 9 Set the pocket tester to “0” before starting a test.

  • Page 87: Ignition System

    ELEC IGNITION SYSTEM IGNITION SYSTEM TROUBLESHOOTING CHART NO SPARK OR WEAK SPARK Inspection steps: 1. Engine oil level 6. Ignition coil (TCI unit) resistance 2. Spark plug 7. Ignition coil (TCI unit) resistance 3. Ignition spark gap 8. Engine switch 4.
  • Page 88 ELEC IGNITION SYSTEM 3. Ignition spark gap 9 Disconnect the spark plug cap 1 from the spark plug. 9 Connect the ignition checker 2 as shown. Spark plug cap 1 → Ignition checker 2 Ignition checker lead → Spark plug 3 9 Turn the crankshaft and measure the ignition spark gap a.
  • Page 89 ELEC IGNITION SYSTEM 4. Spark plug cap resistance 9 Do not pull out the spark plug cap from the 9 Remove the spark plug cap from the high tension cord. high tension cord. 9 Remove → Turn the spark plug cap coun- 9 Connect the pocket tester (Ω...
  • Page 90 ELEC IGNITION SYSTEM 6. Ignition coil (TCI unit) resistance 9 Remove the ignition coil (TCI unit). 9 Connect the pocket tester (Ω × 1) to the primary terminal. Tester + lead → Black/White terminal 1 Tester - lead → Body ground 2 Primary coil resistance: Refer to “SPECIFICATIONS”...
  • Page 91 ELEC IGNITION SYSTEM 8. Engine switch 9 Disconnect the engine switch connec- tors. 9 Connect the pocket tester (Ω × 1) to the engine switch connectors. 9 Check the engine switch continuity. Tester + lead → Black terminal 1 Tester - lead → Black terminal 2 Switch “ON”...
  • Page 92 ELEC IGNITION SYSTEM 9. Oil level switch (With oil warning model) 9 Remove the oil level switch from the bot- tom of the crankcase cover. ( R e fe r t o “ P I S TO N , C A M S H A F T, CRANKCASE, AND CRANKSHAFT”...

  • Page 93: Chapter 6. Troubleshooting

    TRBL ENGINE TROUBLESHOOTING ENGINE ENGINE DOES NOT START Check that the oil warning light comes on by pull- ing the starter rope (With oil warning model). LIGHTS ON DOSE NOT LIGHT Check the connections between the oil warning unit and oil level switch (With oil warning model). GOOD NOT GOOD Replace the oil warning light, oil warning unit, or...
  • Page 94 TRBL ENGINE Remove the spark plug and attach it to the spark plug cap, and then ground the spark plug to check for spark. GOOD SPARK WEAK OR NO SPARK 9 Check the spark plug for dirt and check the spark plug gap.
  • Page 95 TRBL ENGINE Check if the marks on the crankshaft, balancer shaft and camshaft are aligned. Correct. ALIGNED NOT ALIGNED Check if there is seizure, wear, or damage on the piston, piston ring, or cylinder. GOOD SEIZURE OR WORN Repair or replace.
  • Page 96 TRBL ENGINE ENGINE STARTS BUT STALLS Check the fuel level. Add. SUFFICIENT INSUFFICIENT Check if the fuel tank cap is clogged. Clean or replace. GOOD CLOGGED Check if the fuel cock is clogged. Clean. GOOD CLOGGED Check if the fuel hose is clogged. Clean.
  • Page 97 TRBL ENGINE ENGINE SPEED DOES NOT INCREASE Check the spark plug for dirt and check the spark plug gap. DIRTY OR OUT OF GOOD Clean, adjust, or replace. SPECIFICATION Check the air filter element for dirt. Clean. GOOD DIRTY Check the compression pressure. Decarbonize the com- bustion chamber if there TOO HIGH...
  • Page 98 TRBL ENGINE ENGINE SPEED IS UNEVEN Check the fuel level. Add. SUFFICIENT INSUFFICIENT Check if fuel has deteriorated. Replace. GOOD DETERIORATED Check if the fuel tank cap is clogged. Clean or replace. GOOD CLOGGED Check if the fuel cock is clogged. Clean.
  • Page 99 TRBL ENGINE Measure the valve clearance. OUT OF GOOD Adjust. SPECIFICATION Check the valve face and valve seat for wear. Resurface or replace. GOOD WORN Check if there is seizure, wear, or damage on the piston, piston ring, or cylinder. Repair or replace.
  • Page 100 TRBL ENGINE GOVERNOR OPERATION Check that the governor link operate smoothly. Adjust or replace. GOOD NOT GOOD Check that the governor spring is stretched. Replace. GOOD STRETCHED Check the governor adjustment. Adjust. GOOD NOT GOOD Check the governor weight and governor bushing function.
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