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2005
DT125RE
1D01-AE1
DT125X
SERVICE MANUAL

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   Summary of Contents for Yamaha DT125RE 2005

  • Page 1 2005 DT125RE 1D01-AE1 DT125X SERVICE MANUAL...
  • Page 2 EAS00001 DT125RE/X 1D01-1D02/2C81 SERVICE MANUAL © 2005 Yamaha Motor España, S.A. 1st Edition, January 2005 All rights reserved. Any reprinting or unauthorized use without the written permission of Yamaha Motor España, S.A. is expressly prohibited. Printed in Spain.
  • Page 3: Specifications

    EAS00002 NOTICE This manual was produced by the Yamaha Motor España S.A. primarily for use by Yamaha dealers and their qualified mechanics. It is not possible to include all the knowledge of a mechanic in one manual. Therefore, anyone who uses this book to perform maintenance and repairs on Yamaha vehicles should have a basic understanding of mechanics and the techniques to repair these types of vehicles.
  • Page 4: Periodic Checks And

    EAS00007 HOW TO USE THIS MANUAL This manual is intended as a handy, easy-to-read reference book for the mechanic. Comprehensive explanations of all installation, removal, disassembly, assembly, repair and check procedures are laid out with the individual steps in sequential order. The manual is divided into chapters.
  • Page 5: Chassis

    EAS00008 SYMBOLS The following symbols are not relevant to SPEC INFO every vehicle. Symbols indicate the subject of each chapter. CHAS General information Specifications Periodic checks and adjustments Chassis COOL Engine Cooling system Carburetor(s) Electrical system Troubleshooting CARB ELEC Symbols indicate the following.
  • Page 6: Table Of Contents

    EAS00010 TABLE OF CONTENTS GENERAL INFORMATION INFO SPECIFICATIONS SPEC PERIODIC CHECKS AND ADJUSTMENTS CHASSIS CHAS ENGINE COOLING SYSTEM COOL CARBURETOR CARB ELECTRICAL SYSTEM ELEC TROUBLESHOOTING TRBL SHTG...
  • Page 7 INFO...
  • Page 9: Table Of Contents

    INFO CHAPTER 1 GENERAL INFORMATION MOTORCYCLE IDENTIFICATION ……………………………………………1-1 FRAME SERIAL NUMBER ……………………………………………………1-1 ENGINE SERIAL NUMBER……………………………………………………1-1 IMPORTANT INFORMATION …………………………………………………1-2 PREPARATION FOR REMOVAL ……………………………………………1-2 ALL REPLACEMENT PARTS …………………………………………………1-2 GASKETS, OIL SEALS AND O-RINGS ……………………………………1-2 LOCK WASHERS/PLATES AND COTTER PINS……………………………1-2 BEARINGS AND OIL SEALS …………………………………………………1-3 CIRCLIP …………………………………………………………………………1-3 CHECKING THE CONNECTIONS……………………………………………1-4 SPECIAL TOOLS …………………………………………………………………1-5...
  • Page 10: Motorcycle Identification

    MOTORCYCLE IDENTIFICATIONS INFO EAS00014 GENERAL INFORMATION MOTORCYCLE IDENTIFICATION FRAME SERIAL NUMBER The frame IDENTIFICATION number stamped onto the steering head pipe. NOTE: The frame serial number is used to identify the motorcycle and therefore it can be used for the enrollment in the face of the competent autho- rity.
  • Page 11: Important Information

    5. Keep all parts away from any source of fire. EAS00021 REPLACEMENT PARTS Use only genuine Yamaha parts for all replace- ments. Use oil and grease recommended by Yamaha for all lubrication jobs. Other brands may be similar in function and appearance, but inferior in quality.
  • Page 12: Bearings And Oil Seals

    IMPORTANT INFORMATION INFO EAS00024 BEARINGS AND OIL SEALS Install bearings and oil seals so that the manu- facturer’s marks or numbers are visible. When installing oil seals, lubricate the oil seal lips with a light coat of lithium-soap-based grease. Oil bearings liberally when installing, if appro- priate.
  • Page 13: Checking The Connections

    CHECKING THE CONNECTIONS INFO EAS00026 CHECKING THE CONNECTIONS Check the leads, couplers, and connectors for stains, rust, moisture, etc. 1. Disconnect: • lead • coupler • connector 2. Check: • lead • coupler • connector Moisture Dry with an air blower. Rust/stains Connect and disconnect several times.
  • Page 14: Special Tools

    SPECIAL TOOLS INFO EAS00027 SPECIAL TOOLS The following special tools are necessary for complete and accurate tune-up and assembly. Use only the appropriate special tools as this will help prevent damage caused by the use of inappro- priate tools or improvised techniques. Special tools, part numbers or both may differ depending on the country.
  • Page 15 SPECIAL TOOLS INFO Tool No. Tool name / Usage Illustration 90890-01135 Crankcase separation tool This tool is used to remove the crankshaft or separate the crankcase. 90890-01274 (1) Cranckshaft intalling tool -01275 (2) Crankshaft pin -01278 (3) Adapter(M12) 90890-01326 T-Handle This tool is used for holding the damper rod holder when removing or installing the damper rod holder.
  • Page 17 SPEC...
  • Page 19: Table Of Contents

    SPEC CHAPTER 2 SPECIFICATIONS GENERAL SPECIFICATIONS …………………………………………………2-1 ENGINE SPECIFICATIONS……………………………………………………2-4 CHASSIS SPECIFICATIONS …………………………………………………2-6 ELECTRICAL SPECIFICATIONS ……………………………………………2-8 CONVERSION TABLE …………………………………………………………2-10 GENERAL TIGHTENING TORQUE SPECIFICATIONS ……………………2-10 ENGINE ………………………………………………………………………2-11 CHASSIS ……………………………………………………………………2-11 COOLANT FLOW CHART ……………………………………………………2-13 LUBRICATION POINTS AND LUBRICANT TYPE …………………………2-14 ENGINE ………………………………………………………………………2-14 CHASSIS ………………………………………………………………………2-15 CABLE ROUTING ………………………………………………………………2-16...
  • Page 20: Carburetor

    11kW /8000rpm Maximum torque 13Nm/8000rpm Idle speed 1250~1450r/min Starting system Electric starter Lubrication system Yamaha Autolube Oil type or grade: Engine oil 2T motor oil (JASO grade FC) Total amount 1,3L Transmission oil Type SE motor oil Periodic oil change 0,75L (0,79 us.
  • Page 21: General Specifications

    SPEC GENERAL SPECIFICATIONS Model code 1D01/1D02 2C81 Spark plug: Type BR8ES Manufacturer Spark plug gap 0,7~0,8mm (0,0276~0,03315in) Clutch type Wet, multiple disc Transmission: Primary reduction system Helical gear Primary reduction ratio 71/22(3,227) Secondary reduction system chain drive Secondary reduction ratio 57/16(3,563) Transmission type Constant mesh, 6 speed...
  • Page 22 SPEC GENERAL SPECIFICATIONS Model code 1D01/1D02 2C81 Wheel travel: Front wheel travel 270mm(10.63in) 200mm (7,87in) Rear wheel travel 260mm(10.24in) 230mm (9.05in) Electrical: Ignition system Charging system AC Magneto Battery type GT6B-3 Capacity 12V 6Ah Headlight: bulb type Bulb wattage x quantity: Headlight 12V60W/55W x 1 Tail/Brake light...
  • Page 23 SPEC GENERAL SPECIFICATIONS ENGINE Item Standard Limit Cylinder head: Warpage limit * Lines indicate 0,03mm straightedge measurement. Cylinder: Bore size 56.00~56.02mm Taper limit 0.05mm Out of round limit 0.01mm Piston: Piston size “D” 55.950~55.955 Measurement point* 10mm Piston to cylinder clearance 0.045~0.050mm 0.10mm...
  • Page 24 SPEC GENERAL SPECIFICATIONS Item Standard Limit Crankshaft: Crank width “A” 57.90~57.95mm Runout limit “C” 0.03mm Big end side clearance “D” 0.2~0.7mm Small end free play “E” 0.026~0.040mm Clutch: Friction plate thickness 2.9~3.1mm 2.7mm Quantity 7pcs Clutch plate thickness 1.05~1.35mm 0.05mm Quantity 6pcs Clutch spring Free lenght...
  • Page 25 SPEC GENERAL SPECIFICATIONS CHASSIS Item Standard Limit Model code 2C81 2C81 Front wheel: Type Spoke wheels Spoke wheels Rim Size 21x1.60 17 x 3.00 Rim Material Steel Steel Front wheel travel: 270mm 270mm Max. Radial wheel runout Max. Lateral wheel runout 0.5mm 0.5mm Rear wheel:...
  • Page 26 SPEC GENERAL SPECIFICATIONS Item Standard Limit Model code 2C81 2C81 Rear suspension: Type Swingarm Swingarm (link suspension) (link suspension) Rear shock absorber assemby travel 93mm 87 mm Spring free lenght 245mm 250mm Installed lenght 230mm 244mm Spring preload (spring lenght) Hard/Soft Hard/Soft (220/235mm)
  • Page 27 Magneto model/manufacturer F4FU/YAMAHA Pick up coil resistance((ohm)) 310±20%W/R-W/L Source coil resistance ((ohm)) 730±20%B/R-G/W Source coil resistance ((ohm)) 600±20%G/L-G/W CDI unit model/manufacturer 1D0 /YAMAHA Ignition coil: Model/Manufacturer 3RW/YAMAHA Primary coil resistance ((ohm)) 0.23±20% Secondary coil resistance ((ohm)) 7.9±20% Spark plug cap:...
  • Page 28 GENERAL SPECIFICATIONS INFO Indicator light Neutral indicator light 12V3Wx1 Turn indicator light 12V3Wx1 Oil level indicator light 12V3Wx1 High beam indicator light 12V3Wx1 Starting system: System type Electric starter Starter motor: Model/Manufacturer 3MB / Moric Power output 0.2kW Armature coil resistance 0.0315~0.0385<ohm>...
  • Page 29: Conversion Table

    CONVERSION TABLE / SPEC GENERAL TIGHTENING TORQUES SPECIFICATIONS EAS00029 EAS00028 GENERAL TIGHTENING TORQUE CONVERSION TABLE SPECIFICATIONS All specification data in this manual are listed in SI and METRIC UNITS. This chart specifies tightening torques for Use this table to convert METRIC unit data to standard fasteners with a standard ISO thread IMPERIAL unit data.
  • Page 30: Engine

    SPEC DEFINITION OF UNITS TIGHTENING TORQUES ENGINE Tightening Thread torque Part to be tightened Q’ty size m•kg Remarks Spark plug M14x1.25 Cylinder head M8x1.25 Cylinder Stud bolt M8X1.25 LOCTITE screw glue M8x1.25 Power valve holder, Valve cover Cap seal Bolt M5x0.8 Power valve pully Bolt...
  • Page 31 SPEC DEFINITION OF UNITS CHASSIS Tightened Thread torque Parts to be tightened size m•kg Remarks Engine stay (Top) and frame 30-35 3,0-3,5 Cylinder head stay (Top) and frame 30-35 3,0-3,5 Bottom screw (front) engine and frame 60-78 6,0-7,8 Bottom screw (front) engine to swingarm 30-35 3,0-3,5 Steering nut...
  • Page 32: Coolant Flow Chart

    SPEC COOLANT FLOW CHART COOLANT FLOW CHART Water pump Crankcase cover Crankcase Cylinder Cylinder head Bypass hose Thermostatic valve (Thermostatic valve) Outlet hose Radiator Inlet hose Coolant cold (Less than 65°C (149°F)) Coolant hot (165°(149°F) or more) 2-13...
  • Page 33: Lubrication Points And Lubricant Type

    Push rod Apply gear oil Push lever axle Apply gear oil Sliding gear (Transmission) Apply molybdenum disulfide grease Free movement gear (Transmission) Apply molybdenum disulfide grease Guide bar (Shift forks) Apply gear oil Crankcase mating surfaces Yamaha bond no.4 2-14...
  • Page 34 SPEC LUBRICATION POINTS AND LUBRICANT TYPES EAS00032 CHASSIS Lubrication points (part name) Lubricant Type Ball bearing (Steering shaft) Apply lightweight lithium-soap base grease Bearing (Steering shafts) Apply lightweight lithium-soap base grease Oil seal clutch to lever Apply lightweight lithium-soap base grease Clutch lever axle free play Apply lightweight lithium-soap base grease Throttle guide bar...
  • Page 35: Cable Routing

    SPEC CABLE ROUTING CABLE ROUTING Clutch wire A Cover with cap after connecting wires. Right turn signal lead B Route the installation between lower brac- Left turn signal lead ket and headlight bottom holder. Throttle cable C Clamp connection wire. Indicator light wire lead Meter wire lead Headlight bulb wire...
  • Page 36 SPEC CABLE ROUTING CABLE ROUTING Master cylinder A Turn the hose to obtain the desired angle. Front brake hose B Route clutch wire first for the inside, after Wire throttle route the throttle wire. Clutch sw wire lead C Clamp handle wire lead (L). SW handle wire lead (left) D Clamp handle wire lead (R).
  • Page 37 SPEC CABLE ROUTING CABLE ROUTING Main switch wire lead A Route speedometer cable to frame guide. Pipe overflow B Route pipe overflow behind engine holder. Ignition coil C Screw ground wire and rectifier with the Horn same bolt. Flasher relay D Pipe overflow pass behind oil hose.
  • Page 38 SPEC CABLE ROUTING CABLE ROUTING Front brake hose A Route brake hose through the guide. Clutch wire B Clamp clutch wire. Ignition coil C Guide wire (chassis): SW handle wire lead Throttle wire (R), SW handle wire lead (L), clutch SW Therm switch wire lead, front stop SW wire lead, wire Sidestand switch wire lead...
  • Page 41 CHAPTER 3 PERIODIC CHECKS AND ADJUSTMENTS INTRODUCTION/PERIODIC MAINTENANCE/LUBRICATION …………………3-1 ENGINE ……………………………………………………………………………3-2 Y.P.V.S. CABLE ADJUSTMENT ………………………………………………3-2 IDLE SPEED ADJUSTMENT …………………………………………………3-3 THROTTLE CABLE FREE PLAY ADJUSTMENT……………………………3-4 CARBURETOR CABLE FREE PLAY ADJUSTMENT ………………………3-5 AUTOLUBE PUMP STROKE ADJUSTMENT ………………………………3-6 AUTOLUBE PUMP AIR BLEEDING …………………………………………3-6 SPARK PLUG INSPECTION …………………………………………………3-7 IGNITION TIMING CHECK ……………………………………………………3-8 ENGINE OIL LEVEL INSPECTION …………………………………………3-9...
  • Page 42: Periodic Checks And Adjustments

    The annual checks must be performed every year, except if a kilometer-based maintenance is performed instead. • From 30000 km, repeat the maintenance intervals starting from 6000 km. • Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools, data and tech- nical skills. ANUAL ODOMETER READING ( x 1.000 km)
  • Page 43 Y.P.V.S. CABLE ADJUSTMENT ENGINE Y.P.V.S. CABLE ADJUSTMENT 1. Remove • pulley cover (power valve) 2. Turn on the main switch NOTE If the Y.P.V.S. Doesn’t operate, refeer to the “Y.P.V.S. SYSTEM” in CHAPTER 9 3. Check • alignment mark Not aligned Adjust the Y.P.V.S.
  • Page 44 IDLE SPEED ADJUSTMENT IDLE SPEED ADJUSTMENT 1. Adjust: • engine idle speed EAS00054 ADJUSTING THE ENGINE IDLING SPEED NOTE: Prior to adjusting the engine idling speed, the air filter element should be clean, and the engi- ne should have adequate compression. 1.
  • Page 45 ADJUSTING THE THROTTLE CABLE FREE PLAY EAS00058 ADJUSTING THE THROTTLE CABLE FREE PLAY NOTE: Prior to adjusting the throttle cable free play, the engine idling speed and carburetor synch- ronization should be adjusted properly. 1. Check: • throttle cable free play k a Out of specification Adjust.
  • Page 46 ADJUSTING THE THROTTLE CABLE FREE PLAY/ CARBURETOR CABLE FREE PLAY ADJUSTMEN CARBURETOR CABLE FREE PLAY ADJUSTMENT NOTE: Before adjusting carburetor cable, throttle cable free play should be adjusted. 1. Pull back the adjuster cover. 2. Check: • carburetor cable free play k a Out of specification adjust Carburetor Cable Free Play:...
  • Page 47 • Whenever the oil tank has run dry. • Whenever any portion of the engine oil sys- tem is disconnected. 1. Remove: • autolube pump cover 2. Fill: • oil tank Yamaha il 2T or Air-Cooled 2 Stroke Engine Oil...
  • Page 48 AUTOLUBE PUMP AIR BLEEDING/ CHECKING THE SPARK PLUG 3. Air blled: • pump case and/or oil pipe Air bleeding steps • Remove the bleed cap • Start the engine. • Keep the oil running out until air bubbles dissapear. • Keep engine running about...
  • Page 49 CHECKING THE SPARK PLUG/ CHECKING THE IGNITION TIMING 6. Measure: • spark plug gap k a (with a wire Thickness gauge) Out of specification Regap. Spark plug gap 0,7-0,8mm (0,0276-0,03315in) 7. Install: • spark plug Spark plug 20Nm (2,0m·kg, 14ft·lb) NOTE: Before installing the spark plug, clean the spark plug and gasket surface.
  • Page 50 The ignition timing is not adjustable. 4. Install: • Crankcase cover (left) ENGINE OIL LEVEL INSPECTION 1. Check • oil level oil level low Adjust sufficient oil Recommended oil: Yamaha Oil 2T or Air Cooled 2 stroke Engine Oil Oil Tank Capacity: 1,3 L...
  • Page 51: Engine Oil Level Inspection

    ENGINE OIL LEVEL INSPECTION OIL WARNING LIGHT CHECKING METHOD Main Switch “ON” Gears in “NEUTRAL” Oil warning indicator Oil warning indicator light come on light does not come on Shift into gear Oil warning indicator Oil warning indicator light come on light does not come on Refeer to CHAPTER 8 Engine oil level and...
  • Page 52 TRANSMISSION OIL LEVEL INSPECTION/ TRANSMISSION OIL REPLACEMENT TRANSMISSION OIL LEVEL INSPECTION 1. Inspect: • transmission oil level Oil level low Add sufficient oil Transmission oil level steps: • Place the machine on a level surface. • Warm up the engine for several minutes and stop it.
  • Page 53 TRANSMISSION OIL REPLACEMENT/ ADJUSTING THE CLUTCH CABLE FREE PLAY 5. Install: • Drain plug Spark plug 15Nm (1,5m·kg, 11ft·lb) 6. Fill: • Crankcase Recomended oil: SAE 10W30 Type SE Motor Oil Periodic oil change: 0,75L CAUTION • Do not add any chemical additives. Transmission oil also lubricates the clutch and additives could cause clutch slippage.
  • Page 54 ADJUSTING THE CLUTCH CABLE FREE PLAY Direction k a Clutch cable free play is increased. Direction k b Clutch cable free play is decreased. c. Tighten the locknut. NOTE: If the specified clutch cable free play cannot be obtained on the handlebar side of the cable, use the adjusting nut on the engine side.
  • Page 55 ADJUSTING THE CLUTCH CABLE FREE PLAY 7. Disconnect: • Autolube pump cable • Autolube pump hose Refer to the “AUTOLUBE PUMP CABLE AND HOSE” section in the CHAPTER 4. 8. Drain: • Transmission oil Refer to the ”TRANSMISSION OIL REPLA- CEMENT”...
  • Page 56 ADJUSTING THE CLUTCH CABLE FREE PLAY NOTE: • When installing the crankcase cover, engage the autolube pump drive gear with its driven gear as slowly turn the autolube pump shaft. • Tighten the screws (Crankcase cover) in stage, using a crisscross pattern. •...
  • Page 57 ADJUSTING THE CLUTCH CABLE FREE PLAY/ CLEANING THE AIR FILTER ELEMENT 20. Air bleeding: • Autolube pump Refer to the “AUTOLUBE PUMP AIR BLEE- DING section. 21. Install: • Autolube pump cover Screw (autolube pump cover) 5 Nm (0,5 m • kg, 3,6 ft • lb) EAS00089 CLEANING THE AIR FILTER ELEMENT NOTE:...
  • Page 58 CLEANING THE AIR FILTER ELEMENT CAUTION Do not twist the air filter element when squeezing it. 4. Check: • air filter element Damage Replace. 5. Apply the recommended oil to the entire surface of the air filter element and squeeze out the excess oil.
  • Page 59 CARBURETOR JOINT INSPECTIONS /FUEL LINE INSPECTION/CHECKING THE CRANKCASE BREATHER HOSE CARBURETOR JOINT INSPECTION 1. Inspect: • Carburetor joint Crack-damage Replace Refer to the “REED VALVE” section in chap- ter 7 for replacement 2. Check the tightening torque of the carbure- tor joint securing bolts.
  • Page 60 EXHAUST SYSTEM INSPECTION/ENGINE OIL LINE INSPECTION/ COOLANT LEVEL INSPECTION EXHAUST SYSTEM INSPECTION 1 .Inspect: • Gasket (exhaust pipe) • Joint (Silencer) Damage Replace Exhaust gas leakage Repair • Exhaust pipe • Silencer Cracked/Dent/Damage Repair or replace 2. Tighten: • Exhaust pipe •...
  • Page 61 COOLANT LEVEL INSPECTION/ CHANGING THE COOLANT s WARNING Do not remove the radiator cap when the engine is hot. CAUTION Hard water or salt water is harmful to the engine parts; use boiled or distilled water if you can’t get soft water. 4.
  • Page 62 CHANGING THE COOLANT tor cap and slowly turn the radiator cap counterclockwise toward the detent to allow any residual pressure to escape. When the hissing sound has stopped, press down on the radiator cap and turn it coun- terclockwise to remove. The following procedure applies to all of the coolant drain bolts and copper washers.
  • Page 63 CHANGING THE COOLANT with soap and water. • If coolant is swallowed, induce vomiting and get immediate medical attention. CAUTION • Adding water instead of coolant lowers the antifreeze content of the coolant. If water is used instead of coolant check, and if necessary, correct the antifreeze concentration of the coolant.
  • Page 64: Cooling System Inspection

    COOLING SYSTEM INSPECTION COOLING SYSTEM INSPECTION 1. Inspect: • radiator • inlet hose • outlet hose • water outlet pipe cracks-damage Replace Refer to the “COOLING SYSTEM” section ins CHAPTER 6. 3-23...
  • Page 65 ADJUSTING THE FRONT BRAKE/ ADJUSTING THE REAR BRAKE EAS00108 CHASSIS ADJUSTING THE FRONT BRAKE 1. Check: • brake lever free play Out of specification Adjust. Brake lever free play (at the end of the brake lever) 2 ~ 5mm (0,08 ~ 0,20in) 2.
  • Page 66 ADJUSTING THE REAR BRAKE/ CHECKING THE BRAKE FLUID LEVEL 2. Adjust: • brake pedal position a. Loosen the locknut in direction k a or b. Turn the adjusting bolt k b until the specified brake pedal position is obtained. Direction k a Brake pedal is raised.
  • Page 67 CHECKING THE BRAKE FLUID LEVEL 2. Check: REAR • brake fluid level Below the minimum level mark the recommended brake fluid to the proper level. Recommended brake fluid DOT 4 A Front brake B Rear brake s WARNING • Use only the designated brake fluid. Other brake fluids may cause the rubber seals to deteriorate, causing leakage and poor brake performance.
  • Page 68: Checking The Front And Rear Brake Pads, Adjusting The Rear Brake Light Switch

    CHECKING THE FRONT AND REAR BRAKE PADS/ ADJUSTING THE REAR BRAKE LIGHT SWITCH EAS00119 CHECKING THE FRONT AND REAR BRAKE FRONT PADS The following procedure applies to all of the brake pads. 1. Remove: • Rubber plug 2. Operate the brake. 3.
  • Page 69 CHECKING THE FRONT AND REAR BRAKE HOSES/ ADJUSTING THE DRIVE CHAIN SLACK EAS00131 CHECKING THE FRONT AND REAR BRAKE HOSES The following procedure applies to all of the brake hoses and brake hose clamps. 1. Check: • brake hose Cracks/damage/wear Replace.
  • Page 70 ADJUSTING THE DRIVE CHAIN SLACK 3. Check: • drive chain slack k a Out of specification Adjust. Drive chain slack 25 ~ 40 mm DT125X (0,9842 ~ 1,5748 in) 45 ~ 55 mm DT125RE (1,7716 ~ 2,1653 in) 4. Remove: •...
  • Page 71: Lubricating The Drive Chain

    LUBRICATING THE DRIVE CHAIN/ CHEEKING AND ADJUSTING THE STEERING HEAD EAS00142 LUBRICATING THE DRIVE CHAIN The drive chain consists of many interacting parts. If the drive chain is not maintained pro- perly, it will wear out quickly. Therefore, the drive chain should be serviced, especially when the motorcycle is used in dusty areas.
  • Page 72 CHEEKING AND ADJUSTING THE STEERING HEAD a. Remove the lock washer , the upper ring , and the rubber washer b. Loosen the lower ring nut and then tigh- ten it to specification with a steering nut wrench. Steering nut wrench 90890-01403 Lower ring nut (initial tightening torque)
  • Page 73 CHEEKING AND ADJUSTING THE STEERING HEAD/ CHECKING THE FRONT FORK 6. Measure: • steering head tension NOTE: Make sure all of the cables and wires are pro- perly routed. a. Point the front wheel straight ahead. b. Install a plastic locking tie loosely around the end of the handlebar as shown.
  • Page 74 CHECKING THE FRONT FORK/ADJUSTING THE REAR SHOCK ABSORBER ASSEMBLY 2. Check: • inner tube Damage/scratches Replace. • oil seal Oil leakage Replace. 3. Hold the motorcycle upright and apply the front brake. 4. Check: • front fork operation Push down hard on the handlebar several times and check if the front fork rebounds smoothly.
  • Page 75 ADJUSTING THE REAR SHOCK ABSORBER ASSEMBLY/CHECKING THE TIRES 2. Tighten: • Tighten the locknut EAS00164 CHECKING THE TIRES The following procedure applies to both of the tires. 1. Check: • tire pressure Out of specification Regulate. s WARNING • The tire pressure should only be checked and regulated when the tire temperature equals the ambient air temperature.
  • Page 76 España, S.A. for this model. The front and rear tires should always be by the same manufacturer and of the same design. No guarantee concerning handling characteris- tics can be given if a tire combination other than one approved by Yamaha is used on this motorcycle. 3-35...
  • Page 77: Checking The Tires

    CHECKING THE TIRES/ CHECKING AND TIGHTENING THE SPOKES Front tire Manufacturer Model Size DT125RE MICHELIN T63 80/90-21 48P DT125X PIRELLI Sport Demon 120/70-17 58H Rear tire Manufacturer Model Size DT125RE MICHELIN T63 110/80-18 58P DT125X PIRELLI Sport Demon 140/70-17 66H s WARNING •...
  • Page 78 CHECKING AND TIGHTENING THE SPOKES/ CHECKING AND LUBRICATING THE CABLES 2. Tighten: • spoke (with a spoke wrench) 2~3.5 Nm (0.2~0.35 m•kg, 1.42~2.49 ft•lb) NOTE: Be sure to tighten the spokes before and after break-in. EAS00170 CHECKING AND LUBRICATING THE CABLES The following procedure applies to all of the inner and outer cables.
  • Page 79 LUBRICATING THE LEVERS AND PEDALS/LUBRICATING THE SIDESTAND/LUBRICANTING THE REAR SUSPENSION EAS00171 LUBRICATING THE LEVERS AND PEDALS Lubricate the pivoting point and metal-to- metal moving parts of the levers and pedals. Recommended lubricant SAE 10W30 Motor Oil EAS00172 LUBRICATING THE SIDESTAND Lubricate the pivoting point and metal-to- metal moving parts of the sidestand.
  • Page 80: Electrical System

    ELECTRICAL SYSTEM EAS00178 ELECTRICAL SYSTEM CHECKING AND CHARGING THE BATTERY s WARNING Batteries generate explosive hydrogen gas and contain electrolyte which is made of poisonous and highly caustic sulfuric acid. Therefore, always follow these preventive measures: • Wear protective eye gear when handling or working near batteries.
  • Page 81 CHECKING AND CHARGING THE BATTERY NOTE: Since MF batteries are sealed, it is not possi- ble to check the charge state of the battery by measuring the specific gravity of the electroly- te. Therefore, the charge of the battery has to be checked by measuring the voltage at the battery terminals.
  • Page 82 CHECKING AND CHARGING THE BATTERY s WARNING Do not quick charge a battery. CAUTION • Never remove the MF battery sealing caps. • Do not use a high-rate battery charger since it forces a high-amperage current into the battery quickly and can cause battery overheating and battery plate damage.
  • Page 83 CHECKING AND CHARGING THE BATTERY/ CHECKING THE FUSES CAUTION First, connect the positive battery lead and then the negative battery lead 8. Check: • battery terminals Dirt Clean with a wire brush. Loose connection Connect properly. 9. Lubricate: • battery terminals Recommended lubricant Dielectric grease 10.
  • Page 84: Checking The Fuses

    CHECKING THE FUSES/ REPLACING THE HEADLIGHT BULB 3. Replace: • blown fuse a. Set the main switch to “OFF”. b. Install a new fuse of the correct amperage rating. c. Set on the switches to verify if the electrical circuit is operational. d.
  • Page 85 REPLACING THE HEADLIGHT BULB/ ADJUSTING THE HEADLIGHT BEAM 5. Install: • headlight bulbNew Secure the new headlight bulb with the headlight bulb holder. CAUTION Avoid touching the glass part of the head- light bulb to keep it free from oil, otherwise the transparency of the glass, the life of the bulb and the luminous flux will be adversely affected.
  • Page 86 CHAS...
  • Page 88 CHAS CHAPTER 4 CHASSIS FRONT WHEEL …………………………………………………………………4-1 REMOVAL ………………………………………………………………………4-2 INSPECTION……………………………………………………………………4-3 INSTALLATION …………………………………………………………………4-5 REAR WHEEL ……………………………………………………………………4-7 REMOVAL ………………………………………………………………………4-8 INSPECTION……………………………………………………………………4-9 INSTALLATION …………………………………………………………………4-9 FRONT AND REAR BRAKE …………………………………………………4-11 BRAKE PAD REPLACEMENT ………………………………………………4-13 CALIPER DISASSEMBLY ……………………………………………………4-18 MASTER CYLINDER DISASSEMBLY………………………………………4-19 INSPECTION AND REPAIR …………………………………………………4-23 ASSEMBLY ……………………………………………………………………4-27 AIR BLEEDING ………………………………………………………………4-35 FRONT FORK ……………………………………………………………………4-37 REMOVAL ……………………………………………………………………4-38...
  • Page 89 CHAS FRONT WHEEL CHASSIS FRONT WHEEL Bearing Collar Collar Dust cover Oil Seal Wheel axle Spoke Gear unit (speedometer) Basic weight: DT125RE DT125X DT125RE With oil and full fuel tank 126 kg 134 kg A Tire Size: Maximum load* 178 kg (392 lb) 180 kg (396 lb) 80/90-21 48P Cold tire pressure...
  • Page 90 CHAS REMOVING THE FRONT WHEEL EAS00519 REMOVING THE FRONT WHEEL 1. Stand the motorcycle on a level surface. s WARNING Securely support the motorcycle so that there is no danger of it falling over. NOTE: Place the motorcycle on a suitable stand so that the front wheel is elevated.
  • Page 91 CHAS CHECKING THE FRONT WHEEL EAS00526 CHECKING THE FRONT WHEEL 1. Check: • wheel axle Roll the wheel axle on a flat surface. Bends Replace. s WARNING Do not attempt to straighten a bent wheel axle. 2. Check: • tire •...
  • Page 92 CHAS CHECKING THE FRONT WHEEL 6. Check: • collars Damage/wear Replace. s WARNING • After mounting a new tire, ride conserva- tively for a while to become accustomed to the “feel” of the new tire and to allow the tire to seat itself properly in the rim. Failure to do so could lead to an accident with possible injury to the rider or dama- ge to the motorcycle.
  • Page 93: Installing The Front Wheel

    CHECKING THE FRONT WHEEL/ CHAS INSTALLING THE FRONT WHEEL CAUTION Do not contact the wheel bearing inner race or balls. Contact should be made only with the outer race. NOTE: Use a socket that matches the diameter of the wheel bearing outer race and oil seal. EAS00542 INSTALLING THE FRONT WHEEL 1.
  • Page 94 CHAS INSTALLING THE FRONT WHEEL 4. Tighten: • wheel axle 45~70 Nm (4.5~7.0 m•kg, 33~51.3 ft•lb) • Nut (Axle holder): 7.5~12 Nm (0.75~1.2 m•kg, 5.5~8.8 ft•lb) s WARNING Make sure the brake cable is routed pro- perly. CAUTION Before tightening the wheel axle nut, push down hard on the handlebar several times and check if the front fork rebounds smo- othly.
  • Page 95 CHAS REAR WHEEL REAR WHEEL Driven Sprocket Chain puller Collar Bolt Chain puller Bearing Wheel axle Oil Seal Collar Washer Dust Cover Spoke Collar Drive chain Oil Seal Basic weight: DT125RE DT125X DT125RE With oil and full fuel tank 126 kg 134 kg A Tire Size: Maximum load*...
  • Page 96 CHAS REMOVING THE REAR WHEEL EAS00561 REMOVING THE REAR WHEEL 1. Stand the motorcycle on a level surface. s WARNING Securely support the motorcycle so that there is no danger of it falling over. NOTE: Place the motorcycle on a suitable stand so that the rear wheel is elevated.
  • Page 97: Installing The Rear Wheel

    INSPECTING THE REAR WHEEL/ CHAS INSTALLING THE REAR WHEEL INSPECTING THE REAR WHEEL 1. Inspect: • Rear wheel axle Refer to the “FRONT WHEEL - INSPEC- TION” section. 2. Inspect: • Wheel hub • Dust covers (Bearings) • Wheel Refer to the “FRONT WHEEL - INSPEC- TION”...
  • Page 98 CHAS INSTALLING THE REAR WHEEL 2. Adjust: • Drive chain slack k a Drive chain slack: DT125RE 40~55mm (1,77~2,16in.) DT125X 25~40mm (0,98~1,58 in.) • Refer to the “DRIVE CHAIN SLACK ADJUSTMENT” section in CHAPTER 3. Recommended lubricant Lithium-soap-based grease 3. Tighten: •...
  • Page 99 CHAS FRONT AND REAR BRAKE FRONT AND REAR BRAKE Master cylinder cap Brake hose Piston seal Diaphragm Brake caliper Dust seal Master cylinder kit Pad spring Brake pad Master cylinder Piston Brake disc Brake Fluid Type: DOT 4 or DOT 3 Brake pad Wear Limit: 0,8 m (0.03 in.) Brake Disc Wear Limit:...
  • Page 100 CHAS FRONT AND REAR BRAKE Reservoir tank cap protec- Master cylinder Dust seal Master cylinder kit Shim Reservoir tank cap Brake hose Pad spring Inner cap Brake caliper Brake pads Diaphragm Piston Brake disc Reservoir tank Piston seal Reservoir hose 18 Nm (1,8 m •...
  • Page 101 CHAS REPLACING THE FRONT BRAKE PADS EAS00579 CAUTION Disc brake components rarely require disassembly. Therefore, always follow these preventive measures: • Never disassemble brake components unless absolutely necessary. • If any connection on the hydraulic brake system is disconnected, the entire brake system must be disassembled, drained, cleaned, properly filled, and bled after reassembly.
  • Page 102 CHAS REPLACING THE FRONT BRAKE PADS 3. Remove: • brake pads • brake pad springs 4. Measure: • brake pad wear limit k a Out of specification Replace the brake pads as a set. Brake pad wear limit 0.8 mm (0.03 in) 5.
  • Page 103 REPLACING THE FRONT BRAKE PADS/ CHAS REPLACING THE REAR BRAKE PADS 6. Lubricate: • retaining bolt Recommended lubricant Lithium-soap-based grease CAUTION • Do not allow grease to contact the brake pads. • Remove any excess grease. 7. Install: • retaining bolt 18 Nm (1,8 m•kg, 13ft•lb) 8.
  • Page 104 CHAS REPLACING THE REAR BRAKE PADS 1. Remove: • Protector (caliper body) • Retaining bolt • Turn the caliper body counterclockwise 2. Remove: • brake pads • brake pad springs • Shim (brake pad) 3. Measure: • brake pad wear limit k a Out of specification Replace the brake pads as a set.
  • Page 105 CHAS REPLACING THE REAR BRAKE PADS 5. Lubricate: • Retaining bolt (Caliper body) 6. Tighten: • Retaining bolt (Caliper body) 18 Nm (1,8 m•kg, 13ft•lb) 7. Check: • brake fluid level Below the minimum level mark the recommended brake fluid to the proper level.
  • Page 106 CHAS DISASSEMBLING THE FRONT BRAKE CALIPER EAS00618 DISASSEMBLING THE FRONT BRAKE CALIPER NOTE: Before disassembling the brake caliper, drain the brake fluid from the entire brake system. 1. Remove: • union bolt • copper washers • brake hose NOTE: Put the end of the brake hose into a container and pump out the brake fluid carefully.
  • Page 107 DISASSEMBLING THE FRONT BRAKE CALIPER/ CHAS DISASSEMBLING THE REAR BRAKE CALIPER a Blow compressed air into the brake hose joint opening k a to force out the piston from the brake caliper. s WARNING • Cover the brake caliper piston with a rag. Be careful not to get injured when the piston is expelled from the brake caliper.
  • Page 108 CHAS DISASSEMBLING THE REAR BRAKE CALIPER 3. Disconnect the dust boot and then pull out the caliper body from the guide shaft on te caliper bracket 4. Remove: • Rear wheel Refer to the “REAR WHEEL” section. • Caliper bracket 5.
  • Page 109 DISASSEMBLING THE FRONT BRAKE MASTER CHAS CYLINDER EAS00588 DISASSEMBLING THE FRONT BRAKE MASTER CYLINDER NOTE: Before disassembling the front brake master cylinder, drain the brake fluid from the entire brake system. 1. Remove: • Brake switch • Brake lever • Return spring (brake lever) NOTE: When removing the brake switch push the switch hook using a suitable rod, then pull it...
  • Page 110 DISASSEMBLING THE FRONT BRAKE MASTER CYLINDER/DISASSEMBLING THE REAR BRAKE MASTER CHAS CYLINDER 5. Remove: • Cap (master cylinder) • Diaphragm • Dust boot • Circlip • Master cylinder kit NOTE: To collect any remaining brake fluid, place a container under the master cylinder and the end of the brake hose.
  • Page 111 DISASSEMBLING THE REAR BRAKE MASTER CYLINDER/CHECKING THE FRONT AND REAR BRAKE CHAS CALIPER 4. Remove: • Brake hoses • Reservoir tank • Circlip • Push rod • Master cylinder kit 5. Remove: • Cap (reservoir tank) • Inner cap (reservoir tank) •...
  • Page 112 CHAS CHECKING THE FRONT AND REAR BRAKE CALIPER 1. Check: • brake caliper piston Rust/scratches/wear Replace the brake caliper piston. • brake caliper cylinder Scratches/wear Replace the brake caliper assembly. • brake caliper body Cracks/damage Replace the brake caliper assembly. •...
  • Page 113 CHAS CHECKING THE FRONT AND REAR BRAKE CALIPER 3. Check: • Master cylinder Wear/scratches Replace the caliper assembly. • Master cylinder body Cracks/damage Replace. • Oil delivery passage (caliper body) Blow out with compressed air. Front Rear 4. Check: • Master cylinder kit Scratches/Wear/Damage Replace.
  • Page 114 CHAS CHECKING THE FRONT AND REAR BRAKE CALIPER NOTE: • Replace the pad spring as a set if pad replacement is required. • Replace the pads as a set if either if found to be worn to the wear limit. 8.
  • Page 115: Rear Brake Caliper

    ASSEMBLING AND INSTALLING THE FRONT AND CHAS REAR BRAKE CALIPER ASSEMBLING INSTALLING FRONT AND REAR BRAKE CALIPER s WARNING • Before installation, all internal brake components should be cleaned and lubricated with clean or new brake fluid. • Never use solvents on internal brake components as they will cause the pis- ton seals to swell and distort.
  • Page 116 ASSEMBLING AND INSTALLING THE FRONT AND CHAS REAR BRAKE CALIPER 4. Install: • Piston seal • Dust seal • Clip • Caliper piston s WARNING Always use new piston seal and dust seal. CAUTION Install the clip into the slot on the caliper body correctly.
  • Page 117 ASSEMBLING AND INSTALLING THE FRONT AND CHAS REAR BRAKE CALIPER 8. Install: • Copper washers • Brake hose • Union bolt Union bolt: 26 Nm (2.6m•kg, 19ft•lb) CAUTION When installing the brake hoses to the cali- and master cylinder lightly touch the brake pipe with the projections them.
  • Page 118 ASSEMBLING AND INSTALLING THE FRONT AND CHAS REAR BRAKE CALIPER 10. Bleed: • brake system Refer to “AIR BLEEDING” section. 11. Check: • brake fluid level Below the minimum level mark k a the recommended brake fluid to the proper level.
  • Page 119 ASSEMBLING AND INSTALLING THE FRONT AND CHAS REAR BRAKE CALIPER ASSEMBLING INSTALLING FRONT AND REAR BRAKE CALIPER 1. Install: • Master cylinder kit • Push rod • Circlip • Dust boot • Brake hoses • Cooper washers • Union bolt •...
  • Page 120 ASSEMBLING AND INSTALLING THE FRONT AND CHAS REAR BRAKE CALIPER NOTE: When installing the caliper piston , be sure to have it’s open end facing the caliper cylinder 4. Install: • Caliper bracket • Rear wheel Refer to the “REAR WHEEL INSTALLA- TION”...
  • Page 121 ASSEMBLING AND INSTALLING THE FRONT AND CHAS REAR BRAKE CALIPER 7. Install: • Cooper washers • Brake hose • Union bolt • Protector (Caliper body) Union Bolt: 26 Nm (2.6 m•kg, 19 ft•lb) CAUTION When installing the brake hoses to the cali- and master cylinder , lightly touch the brake pipe with the projections...
  • Page 122 ASSEMBLING AND INSTALLING THE FRONT AND CHAS REAR BRAKE CALIPER 9. Bleed: • brake system Refer to “AIR BLEEDING” section. 10. Check: REAR • brake fluid level Below the minimum level mark the recommended brake fluid to the proper level. Refer to “BRAKE FLUID INSPECTION”...
  • Page 123 CHAS BLEEDING THE HYDRAULIC BRAKE SYSTEM EAS00134 BLEEDING THE HYDRAULIC BRAKE SYSTEM s WARNING Bleed the hydraulic brake system whene- ver: • the system is disassembled. • a brake hose is loosened, disconnected or replaced. • the brake fluid level is very low. •...
  • Page 124 CHAS BLEEDING THE HYDRAULIC BRAKE SYSTEM NOTE: Loosening the bleed screw will release the pressure and cause the brake lever to contact the throttle grip or the brake pedal to fully extend. h. Tighten the bleed screw and then release the brake lever or brake pedal.
  • Page 125: Front Forks

    CHAS FRONT FORKS FRONT FORKS Cap bolt Damper rod Washer O-ring Oil lock pieces Slide bush Spacer Circlip Outer fork tube Spring seat Dust seal Axle holder Fork spring Oil seal Fork boot Inner fork tube FOR OIL (EACH): FOR SPRING: CAPACITY: MINIMUM FREE 495 cm...
  • Page 126 CHAS REMOVAL/DISASSEMBLY REMOVAL s WARNING Support the motorcycle securely so there is no danger of it falling over. 1 Elevate the front wheel by placing a suitable stand under the engine. 2. Remove: • Brake caliper assembly 3. Loosen: • upper bracket pinch bolt •...
  • Page 127 CHAS REMOVAL/DISASSEMBLY 3. Drain: • Fork oil 4. Remove: • Retaining clip Use a thin slotted head screwdriver • Washer CAUTION Take care not to scratch the inner tube 5. Remove: • Bolt (Damper rod) • Cooper washer NOTE: Hold the damper rod to loosen the bolt (Damper rod) by the T-handle and the Holder...
  • Page 128 CHAS DISASSEMBLY/CHECKING THE FRONT FORK LEGS 7. Remove: • Inner fork tube a. Hold the front fork leg horizontally. b. Securely clamp the brake caliper bracket in a vise with soft jaws. c. Separate the inner tube from the outer tube by pulling the inner tube forcefully but care- fully.
  • Page 129 CHECKING THE FRONT FORK LEGS/ASSEMBLING CHAS THE FRONT FORK LEGS 3. Check: • damper rod • piston ring Damage/wear Replace. Obstruction Blow out all of the oil pas- sages with compressed air. • rebound spring Damage Replace. 4. Check: • cap bolt O-ring Damage/wear Replace.
  • Page 130 CHAS ASSEMBLING THE FRONT FORK LEGS 2. Lubricate: • inner tube’s outer surface Recommended lubricant Fork oil 10W or equivalent 3. Tighten: • damper rod assembly bolt 62 Nm (6.2 m•kg, 45 ft•lb) LOCTITE® NOTE: While holding the damper rod assembly with the damper rod holder and T-handle, tighten the damper rod assembly bolt.
  • Page 131 Quantity (each front fork leg) DT125RE 0.495 L DT125X 0.6 L Recommended oil Yamaha fork and shock oil 10W or equivalent Front fork leg oil level (from the top of the inner tube, with the inner tube fully compressed and without the fork spring) DT125RE 165.5 mm (6.52 in)
  • Page 132: Assembling The Front Fork Legs

    CHAS ASSEMBLING THE FRONT FORK LEGS NOTE: • While filling the front fork leg, keep it upright. • After filling, slowly pump the front fork leg up and down to distribute the fork oil. 9. Install: • spring • spring seat •...
  • Page 133: Steering Head And Handlebars

    CHAS STEERING HEAD AND HANDLEBARS STERING HEAD AND HADLEBARS Handlebar Cover Handlebar grip (Right) Bearing race Handlebar grip (Left) Headlight stay Handlebar holder (Upper) Handlebar crown Ring nut TIGHTENING STEPS •Tightening ring nut 35Nm to 40Nm (3.5 to 4.0 m•kg, 25.6 to 29.3 ft•lb) •Loosen it fully •Retighten it 3Nm to 5Nm (0.3 to 0.5 m•kg, 2.2 to 3.6 ft•lb)
  • Page 134 CHAS REMOVAL REMOVAL 1. Elevate the front wheel by placing a suitable stand under the engine. s WARNING Securely support the motorcycle so there is no danger of falling over 2. Remove: • Front wheel Refer to the “FRONT WHEEL REMOVAL” section.
  • Page 135 CHAS REMOVAL 7. Remove: • Flasher lights (left and right) • Brake hose guide (From left side only) 8. Disconnect: • Speedometer cable 9. Remove: • Bands 10. Disconnect: • Meter leads • Handlebar switch leads • Main switch leads •...
  • Page 136 CHAS REMOVAL 15. Loosen: • Screws (throttle cable housing) 16. Remove: • Handlebar holders • Handlebars NOTE: For completely removal of the handlebar, be sure to clear the throttle cable housing 17. Remove: • Flange nut • Handlebar crown 18. Remove: •...
  • Page 137 CHAS REMOVAL/INSPECTION 19. Remove: • Bearing cover • Ball race (Top-Upper) • Ball bearing (22pcs) INSPECTION 1. Wash the bearing in solvent. 2. Inspect: • Bearings • Bearing races Pitting/Damage Replace • Dust seal Wear/Damage Replace Bearing race replacement steps: •...
  • Page 138 CHAS INSPECTION/INSTALLATION 4. Inspect: • Handlebar Cracks/Bend/Damage Replace s WARNING Do not attempt to straighten a bent handle- bar as this may dangerously weaken the handlebar. Handlebar replacement steps: • Remove the hadlebar grip and handlebar switch (Left) and lever holder. •...
  • Page 139 CHAS INSTALLATION 3. Install: • Ball race (Upper-Lower) • Bearing cover • Under bracket • Ring nut s WARNING Hold the under bracket until its secured 4. Tighten: • Ring nut Tightening steps: • Tighten the ring nut using the Ring Nut Wrench Ring Nut Wrench: 90890-01403...
  • Page 140 CHAS INSTALLATION 6. Install: • Meter assembly Bolt (Meter assembly): 5Nm to 8Nm (0.5 to 0.8 m·kg, 3.6 to 5.8 ft·lb) 7. Install: • Front fork Refer to the “FRONT FORK INSTALLA- TION” section. Pinch Bolt (Under Bracket): 20 to 25Nm (2.0 to 2.5 m·kg, 14.6 to 18.3 ft·lb) NOTE: In this stage, temporarily tighten the pinch...
  • Page 141 CHAS INSTALLATION 9. Install: • Handlebar • Handlebar holders Bolt (Handlebar holder): 12 to 28 Nm (1.2 a 2.8 m·kg, 8.80 to 20.5ft·lb) NOTE: The handlebar should be installed in the posi- tion assigned by the position mark CAUTION First tighten the bolts on the front side of the handlebar holder, and then tighten the bolts on the rear side.
  • Page 142 CHAS INSTALLATION 12. Install: • Headlight lens unit 13. Install: • Front wheel Refer to the “FRONT WHEEL INSTALLA- TION” section. Front wheel axle: 80 to 100 Nm (8.0 a 10.0 m·kg,58.6 to 73.3ft·lb) Axle security bolts: 7.5 to 12 Nm (0.75 to 1.2 m·kg, 5.5 to 8.8.5ft·lb) 14.
  • Page 143: Rear Shock Absorber And Swingarm

    CHAS REAR SHOCK ABSORBER AND SWINGARM REAR SHOCK ABSORBER AND SWINGARM Rear shock absorber assembly Spring Bush SPRING PRELOAD (INSTALLED): SPRING PRELOAD (INSTALLED): FOR DT125RE FOR DT125X STANDARD LENGTH: STANDARD LENGTH: 230 mm 244 mm MINIMUM LENGTH: MINIMUM LENGTH: 220 mm 234 mm MAXIMUM LENGTH: MAXIMUM LENGTH:...
  • Page 144 CHAS REAR SHOCK ABSORBER AND SWINGARM Swingarm Bearing Relay arm Oil seal Connecting arm Bush Chain case Plain washer Chain guard Shim Chain guide Thrust cover Collar 3 to 5 Nm (0,3 to 0,5 m • kg, 2,2 to 3,6 ft•lb) 2 to 4 Nm (0,2 to 0,4 m •...
  • Page 145 HANDLING THE REAR SHOCK ABSORBER/DISPO- CHAS SING OF A REAR SHOCK ABSORBER/REMOVING EAS00686 HANDLING THE REAR SHOCK ABSORBER s WARNING This rear shock absorber contains highly compressed nitrogen gas. Before handling the rear shock absorber, read and make sure you understand the following informa- tion.
  • Page 146 REMOVING THE REAR SHOCK ABSORBER CHAS ASSEMBLY NOTE: Place the motorcycle on a suitable stand so that the rear wheel is elevated. 2. Remove: • Bolt (Connecting arm swingarm) (from swingarm side) 3. Remove: • Bolt (Shock absorber Lower) s WARNING When removing the lower bolt hold the swingarm...
  • Page 147 CHAS REMOVING THE SWINGARM ASSEMBLY REMOVING THE SWINGARM ASSEMBLY s WARNING Securely support the motorcycle so there is no danger of falling it over 1. Elevate the rear wheel by placing a suitable stand under the engine. 2. Remove: • Rear shock absorber Refer to the “REAR SHOCK ABSORBER”...
  • Page 148 CHAS REMOVING THE SWINGARM ASSEMBLY 7. Check: • Swingarm free play Inspection steps • Check the tightening torque of the pivot shaft (swingarm) securing nut Nut (Swingarm-Pivot shaft): 80 to 100Nm (8 to 10 m·kg; 58.6 to 73.3lb·ft) • Check the swingarm side play by moving it from side to side.
  • Page 149 CHAS REMOVING THE SWINGARM ASSEMBLY 10. Remove: • Relay arm 11. Remove: • Chain protector 12. Remove: • Thrust covers • Inner collars (Swingarm) • Inner collars (Connecting arm) • Inner collar (Relay arm) 4-61...
  • Page 150 CHECKING THE REAR SHOCK ABSORBER CHAS ASSEMBLY EAS00695 CHECKING THE REAR SHOCK ABSORBER ASSEMBLY 1. Check: • rear shock absorber rod Bends/damage Replace the rear shock absorber assembly. • rear shock absorber Gas leaks/oil leaks Replace the rear shock absorber assembly. •...
  • Page 151 CHAS CHECKING THE SWINGARM 4. Check: • dust covers • spacer • washers • oil seals Damage/wear Replace. • bearings Damage/pitting Replace. 5. Check: • connecting arms • relay arm Damage/wear Replace. 6. Check: • bearings • oil seals Damage/pitting Replace.
  • Page 152 CHECKING THE SWINGARM/INSTALLING THE CHAS SWINGARM 7. Check: • spacers Damage/scratches Replace. EAS00711 INSTALLING THE SWINGARM 1. Lubricate: • bearings • spacers • dust covers • pivot shaft Recommended lubricant Molybdenum disulfide grease 2. Install: • relay arm 45 to 70 Nm (4.5 to 7.0m•kg, 33 to 95.5ft•lb) •...
  • Page 153: Installing The Swingarm

    CHAS INSTALLING THE SWINGARM 4. Adjust: • drive chain slack Refer to “ADJUSTING THE DRIVE CHAIN SLACK” in chapter 3. Drive chain slack DT125RE 40~55mm (1,77~2,16in.) DT125X 25~40mm (0,98~1,58 in.) 4-65...
  • Page 154 CHAS DRIVE CHAIN AND SPROCKETS DRIVE CHAIN AND SPROCKETS Drive sprocket Chain joint Drive chain DRIVE CHAIN TYPE 428V2 No. OF LINKS DRIVE CHAIN SLACK DT125RE 45~55mm (1,77~2,16in) DRIVE CHAIN SLACK DT125X 25~40mm (0,984~1,575in) 32 to 37 Nm (3,2 to 3,7 m • kg, 23,5 to 27,1 ft•lb) 4-66...
  • Page 155 CHAS REMOVING THE DRIVE CHAIN REMOVING THE DRIVE CHAIN 1. Stand the motorcycle on a level surface. s WARNING Securely support the motorcycle so that there is no danger of it falling over. NOTE: Place the motorcycle on a suitable stand so that the rear wheel is elevated.
  • Page 156 REMOVING THE DRIVE CHAIN/CHECKING THE DRIVE CHAS CHAIN 8. Remove: • Chain guide rollers (Upper and lower) EAS00709 CHECKING THE DRIVE CHAIN 1. Measure: • ten-link section k a of the drive chain Out of specification Replace the drive chain. Ten-link drive chain section limit (maximum) 120 mm (4.72 in)
  • Page 157 CHAS CHECKING THE DRIVE CHAIN CAUTION This motorcycle has a drive chain with small rubber O-rings between the drive chain side plates. Never use high-pressure water or air, steam, gasoline, certain sol- vents (e.g., benzine), or a coarse brush to clean the drive chain.
  • Page 158 CHAS INSTALLING THE DRIVE CHAIN EAS00713 INSTALLING THE DRIVE CHAIN 1. Lubricate: • drive chain • master link <NEW> Recommended lubricant Engine oil or chain lubricant sui- table for O-ring chains 2. Install: • drive chain • drive sprocket • washer •...
  • Page 159 CHAS INSTALLING THE DRIVE CHAIN CAUTION A drive chain that is too tight will overload the engine and other vital parts, and one that is too loose can skip and damage the swingarm or cause an accident. Therefore, keep the drive chain slack within the speci- fied limits.
  • Page 162 CHAPTER 5 ENGINE ENGINE REMOVAL……………………………………………………………………5-1 SIDE COVERS …………………………………………………………………5-1 COOLANT ………………………………………………………………………5-1 TRANSMISSION OIL …………………………………………………………5-1 EXHAUST PIPE ………………………………………………………………5-2 CARBURETOR …………………………………………………………………5-2 AUTOLUBE PUMP CABLE AND HOSE ……………………………………5-2 CLUTCH CABLE ………………………………………………………………5-3 Y.P.V.S. CABLES ………………………………………………………………5-3 RADIATOR HOSE………………………………………………………………5-4 LEADS …………………………………………………………………………5-4 DRIVE CHAIN …………………………………………………………………5-5 ENGINE DISASSEMBLY…………………………………………………………5-6 CYLINDER HEAD, CYLINDER AND PISTON ………………………………5-8 CLUTCH, PRIMARY DRIVE GEAR AND BALANCER GEAR ……………5-8 CLUTCH PUSH LEVER………………………………………………………5-11 SHIFT SAHFT AND STOPPER LEVER ……………………………………5-11...
  • Page 163: Engine Overhaul

    ENGINE REMOVAL ENGINE OVERHAUL ENGINE REMOVAL NOTE: It’s not necessary to remove the engine in order to remove the following components: • Cylinder head • Cylinder • Piston and piston ring • Power valve • Clutch • Primary drive gear •...
  • Page 164 ENGINE REMOVAL EXHAUST PIPE 1. Loosen: • Bolts (Exhaust holder) • Screw (muffler joint) 2. Remove: • A.I.S. hose • Bolts (Exhaust pipe) • Exhaust pipe CARBURETOR 1. Remove: • Fuel tank • Carburetor Refer to the “CARBURETOR REMOVAL” section in chapter 6. AUTOLUBE PUMP CABLE AND HOSE 1.
  • Page 165 ENGINE REMOVAL CLUTCH CABLE 1. Loosen: • Adjuster (Clutch cable) 2. Loosen: • Adjuster lock nuts (Clutch cable) 3. Disconnect: • Clutch cable (from clutch push lever and cable guide Y.P.V.S. CABLES 1. Remove: • Pulley cover (Power valve) 2. Remove: •...
  • Page 166 ENGINE REMOVAL 3. Disconnect: • Servomotor unit leads 4. Remove: • Servomotor unit • Adjuster (Y.P.V.S. cable) • Pulley housing RADIATOR HOSES 1. Disconnect: • Radiator hose (Inlet) 2. Disconnect: • Radiator hose (Outlet) LEADS 1. Disconnect: • Battery lead (Negative) 2.
  • Page 167 ENGINE REMOVAL 3. Disconnect: • CDI magneto leads 4. Remove: • Bands DRIVE CHAIN 1. Remove: • Change pedal • Crankcase cover (Left) • Gasket (Crankcase cover) 2. Straighten: • Lock washer tab 3. Loosen: • Nut (Drive sprocket) NOTE: When loosening the nut (Drive sprocket) apply the rear brake pedal and transmission gear to the 6th position...
  • Page 168: Engine Disassembly

    ENGINE REMOVAL/ ENGINE DISASSEMBLY 2. Remove: • Bolt (Engine mount Rear lower) • Pivot shaft NOTE: The engine and swingarm are installed using the same pivot shaft. Therefore, take care so that the pivot shaft is pulled, not entirely, out, but for enough to set the engine free.
  • Page 169 ENGINE DISASSEMBLY 2. Remove: • Spark plug • Thermo unit s WARNING Handle the thermo unit with special care. Never subject it to strong or allow it to be dropped. In case of being dropped, it must be replaced. 3. Remove: •...
  • Page 170 ENGINE DISASSEMBLY EAS00253 REMOVING THE CYLINDER AND PISTON 1. Remove: • piston pin clip • piston pin • piston CAUTION Do not use a hammer to drive the piston pin out. NOTE: • Before removing the piston pin clip, cover the crankcase opening with a clean rag to prevent the piston pin clip from falling into the crankcase.
  • Page 171 ENGINE DISASSEMBLY 1. Remove: • Water outlet pipe • O-Ring (from water outlet pipe) Right side Left side 2. Remove: • Crankcase cover (Right) • Dowel pins • Gasket (Crankcase cover) 3. Remove: • Bolts • Clutch springs • Pressure plate •...
  • Page 172 ENGINE DISASSEMBLY NOTE: • Before loosening the nut (Clutch boss) straighten the lock washer tab. • Hold the clutch boss to loosen the nut (Clutch boss) by the universal Clutch hol- Universal Clutch Holder 90890-04086 4. Straighten: • Lock washer tab 5.
  • Page 173 ENGINE DISASSEMBLY 8. Remove: • Spacer collar • Oil seal retainer CLUTCH PUSH LEVER 1. Unhook: • Return spring (Push lever) 2. Remove: • Push lever (Clutch) • Return spring • Washer SHIFT SHAFT AND STOPPER LEVER NOTE: With the engine mounted, the shift shaft can be maintained by removing the following parts.
  • Page 174 ENGINE DISASSEMBLY ROTOR NOTE: With the engine mounted, the rotor can be maintained by removing the following parts: • Crankcase cover (Left). 1. Remove: • Nut (Rotor) • Plain washer NOTE: Hold the rotor to loosen the nut (Rotor) by the Universal Rotor Holder Universal Rotor Holder 90890-01235...
  • Page 175 ENGINE DISASSEMBLY 1. Remove: • Carburetor joint • Reed valve assemby • Gasket CRANKCASE RIGHT 1. Remove: • Crankcase (Right) NOTE: • Loosen the bolts starting with the highest numbered one. • Loosen each bolt 1/4 turn and remove them after all bolts are loosened. Removal steps: •...
  • Page 176 ENGINE DISASSEMBLY CAUTION • Use soft hammer to tap on the case half. • Tap only on reinforced portions of case. • Don’t tap on gasket mating surface. • Work slowly and carefully. • Make sure the case halves separate evenly.
  • Page 177 ENGINE DISASSEMBLY 3. Remove: • Balancer weight CRANKSHAFT 1. Remove: • Crankshaft NOTE: • Remove the crankshaft with the Crankcase Separating Tool • Fully tighten the tool holding bolts, but make sure the tool body is parallel with the case. If necessary, one screw may be bac- ked out slightly to level tool body.
  • Page 178 ENGINE DISASSEMBLY 1. Remove: • Hose guide • Power valve holder (Right) 2. Remove: • Bolt (Power valve) NOTE: When loosening the power valve connecting bolt , lock the valve by inserting a wooden pice into the exhaust port. 3. Remove: •...
  • Page 179 ENGINE DISASSEMBLY/ INSPECTION AND REPAIR 1. Remove:(ref. oilpump) • Circlip • Drive gear (autolube pump) • Circlip • Oil seal • Collar • • Drive shaft (autolube pump) • O-Ring • Autolube pump EAS00227 CHECKING THE CYLINDER HEAD 1. Eliminate: •...
  • Page 180 INSPECTION AND REPAIR a. Place a straightedge and a thickness gauge across the cylinder head. b. Measure the warpage. c. If the limit is exceeded, resurface the cylin- der head as follows. d. Place a 400 ~ 600 grit wet sandpaper on the surface plate and resurface the cylinder head using a figure-eight sanding pattern.
  • Page 181 INSPECTION AND REPAIR Standard Limit Cylinder Bore “C” 56.00 ~ 56.02 mm (2.204 ~ 2.205 in) Taper “T” — 0.05 mm (0.001968 in) Out of — 0.01 mm round “R” (0.00039 in) C = maximum of D T = maximum of D or D - maximum of or D...
  • Page 182 INSPECTION AND REPAIR NOTE: Before measuring the piston ring side clearan- ce, eliminate any carbon deposits from the piston ring grooves and piston rings. Piston ring side clearance Top ring 0.02 ~ 0.060 mm (0.0008 ~ 0.0024 in) 2nd ring 0.035 ~ 0.070 mm (0.0014 ~ 0.0028 in) 2.
  • Page 183 INSPECTION AND REPAIR Piston ring oversize • Top and 2nd piston rings The size of the top and 2nd oversize piston rings is stamped on the top of each ring. Oversize 25 mm Oversize 50 mm PISTON PIN AND BEARING 1.
  • Page 184 INSPECTION AND REPAIR 2. Measure: • friction plate thickness Out of specification Replace the fric- tion plates as a set. NOTE: Measure the friction plate at four places. Friction plate thickness 2.9 ~ 3.1 mm (0.11 ~ 0.12 in) <Limit>: 2.7 mm EAS00281 CHECKING THE CLUTCH PLATES The following procedure applies to all of the...
  • Page 185 INSPECTION AND REPAIR 2. Measure: • clutch spring free length Out of specification Replace the clutch springs as a set. Clutch spring free length 34,5mm (1.36 in) EAS00284 CHECKING THE CLUTCH HOUSING 1. Check: • clutch housing dogs Damage/pitting/wear Deburr the clutch housing dogs or replace the clutch housing.
  • Page 186 INSPECTION AND REPAIR EAS00288 CHECKING THE CLUTCH PUSH RODS 1. Check: • O-ring • short clutch push rod • long clutch push rod • ball Cracks/damage/wear Replace the defective part(s). 2. Measure: • long clutch push rod bending limit Out of specification Replace the long clutch push rod.
  • Page 187 INSPECTION AND REPAIR EAS00421 CHECKING THE SHIFT FORKS The following procedure applies to all of the shift forks. 1. Check: • shift fork cam follower • shift fork pawl Bends/damage/scoring/wear Replace the shift fork. 2. Check: • shift fork guide bar Roll the shift fork guide bar on a flat surface.
  • Page 188 INSPECTION AND REPAIR EAS00423 CHECKING THE TRANSMISSION 1. Measure: • main axle runout (with a centering device and dial gauge Out of specification Replace the main axle. Main axle runout limit 0.08 mm (0.0031 in) 2. Measure: • drive axle runout (with a centering device and dial gauge Out of specification Replace the drive...
  • Page 189 INSPECTION AND REPAIR EAS00328 CHECKING THE SHIFT SHAFT 1. Check: • shift shaft • shift pawls Bends/damage/wear Replace. 2. Check: • stopper lever Roller turns roughly Replace Bend/damage Replace 3. Check: • Return spring (shift shaft) • Return spring (Shift pawls) •...
  • Page 190 INSPECTION AND REPAIR 3. Measure: • crankshaft width Out of specification Replace the crankshaft. Crankshaft width 57.9~57.95 mm (2.279~2.281 in) 4. Check: • crankshaft sprocket Damage/wear Replace the cranks- haft. • bearing Cracks/damage/wear Replace the crankshaft. AUTOLUBE PUMP Wear or an internal malfunction may cause pump output to vary from the factory settings.
  • Page 191 INSPECTION AND REPAIR 3. Check: • Pump output. Out of specification Adjust. Minimum output/200 stroke: 0.38 ~ 0.50cm3 (0.02 ~ 0.03cu.in) Maximum output/200stroke: 4.65 ~ 5.15cm3 (0.28 ~ 0.31cu.in) 4. Check: • Drive gear (Autolube pump) • Drive shaft (Autolube pump) •...
  • Page 192 INSPECTION AND REPAIR EAS00399 CHECKING THE CRANKCASE 1. Thoroughly wash the crankcase halves in a mild solvent. 2. Thoroughly clean all the gasket surfaces and crankcase mating surfaces. 3. Check: • crankcase Cracks/damage Replace. • oil delivery passages Obstruction Blow out with compressed air.
  • Page 193 ENGINE ASSEMBLY AND ADJUSTMENTS AUTOLUBE PUMP Autolube pump Collar End cap O-Ring Hose Screw Clip Oil seal Adjusting bolt Autolube pump gear Washer Drive shaft Circlip 5 Nm (0.5 m • kg, 3.6ft•lb) 5-31...
  • Page 194 ENGINE ASSEMBLY AND ADJUSTMENTS AUTOLUBE PUMP 1. Lubricate: • Oil seal lips Lightweight Lithium-soap base grease 2. Install: • Drive shaft (autolube pump) • Circlip • Pin • Drive gear (autolube pump) • Circlip • O-ring • Autolube pump Screw (Autolube pump): 5 Nm (0.5m•kg;...
  • Page 195 ENGINE ASSEMBLY AND ADJUSTMENTS POWER VALVE Power valve Pulley housing Power valve holder (right) Pulley O-ring Pulley cover Power valve holder (left) Y.P.V.S. Cable Gasket seal 7 Nm (0.7 m • kg, 5.1ft•lb) USE NEW ONE 10 Nm (1.0 m • kg, 7.2ft•lb) USE NEW ONE 7 Nm (0.7 m •...
  • Page 196 ENGINE ASSEMBLY AND ADJUSTMENTS POWER VALVE 1. Lubricate: • Power valve connecting rod Molybdenum Disulfide Grease • O-rings • Gasket seal • Bushes (Power valve shaft contact surface) • Power valve surface Lightweight Lithium-soap base grease 2. Install: • Power valve holder (Left) •...
  • Page 197 ENGINE ASSEMBLY AND ADJUSTMENTS CRANKSHAFT/PISTON/BALANCER Balancer gear Bearing Thrust bearing Bearing Piston ring set Connecting rod Straight key Piston Crank pin Balancer weight Piston pin Big end bearing Bearing Piston pin clip Crank (Left) Drive gear Small end bearing Wodruff key Oil seal Staight key Bearing...
  • Page 198 ENGINE ASSEMBLY AND ADJUSTMENTS TRANSMISSION Main axle Cylindrical bearing Special washer 2nd pignion gear Drive axle Oil seal 3rd 4th pignion gear 1st wheel gear Drive sprocket 5th pignion gear 2nd wheel gear Lock washer 6th pignion gear 3rd wheel gear Plain washer 4th wheel gear Circlip...
  • Page 199 ENGINE ASSEMBLY AND ADJUSTMENTS SHIFTER Shift cam Shift fork #2 Stopper lever Shift fork #3 Return spring Shift fork #1 Securing bolt Shift fork #2 Shift fork #1 14 Nm (1.4 m • kg,10ft•lb) 5-37...
  • Page 200 ENGINE ASSEMBLY AND ADJUSTMENTS EAS00408 INSTALLING THE CRANKSHAFT 1. Install: • crankshaft assembly NOTE: • Install the crankshaft assembly with the crankshaft installer pot, crankshaft installer bolt, adapter (M12) and spacer. Crankshaft installer pot 90890-01274 Crankshaft installer bolt 90890-01275 Adapter (M12) 90890-01278 Spacer 90890-01288...
  • Page 201 CRANKCASE (RIGHT) 1. Install: • Bearing retainer Screw (Bearing retainer): 7 Nm (0.7 m•kg; 5.1 ft•lb) Use Loctite® 2. Apply: • yamaha Bond nº4 (to mating surface of both crankcase hal- ves) Yamaha Bond nº4: 90890-05143 3. Install: • Damper collar •...
  • Page 202 ENGINE ASSEMBLY AND ADJUSTMENTS CAUTION Before installing and torquing the bolts (Crankcase) be sure to check wheter the transmission is functioning properly by manually rotating the shift cam either way. NOTE: Tighten the bolts (Crankcase) in stage, using a crisscross pattern. Bolts(Crankcase): 8 Nm (0.8 m•kg;...
  • Page 203 ENGINE ASSEMBLY AND ADJUSTMENTS MAGNETO ROTOR Stator assembly Rotor Washer 80 Nm (8.0 m • kg, 58ft•lb) 5-41...
  • Page 204 ENGINE ASSEMBLY AND ADJUSTMENTS MAGNETO ROTOR 1. Install: • Stator Screw(Stator): 8 Nm (0.8 m•kg; 5.8 ft•lb) Use Loctite® 2. Connect: • Neutral switch lead 3. Install: • Woodruf key • Rotor • Plain washer • Nut (Rotor) NOTE: • Clean the tapered portions of the cranks- haft and rotor.
  • Page 205 ENGINE ASSEMBLY AND ADJUSTMENTS SHIFT SHAFT Shift tank Spring Circlip Oil seal Change pedal 15 Nm (1.5 m • kg, 11ft•lb) 5-43...
  • Page 206 ENGINE ASSEMBLY AND ADJUSTMENTS STOPPER LEVER AND SHIFT SHAFT 1. Install: • Return spring • Stopper lever 14Nm (1.4m•kg, 10 ft•lb) NOTE: • Mesh the stopper lever with the shift cam. 2. Install: • shift shaft NOTE: • Lubricate the oil seal lips with lithium- soap-based grease.
  • Page 207 ENGINE ASSEMBLY AND ADJUSTMENTS 2. Install: • Washer • Return spring • Push lever 3. Set the return spring to the spring hook 5-45...
  • Page 208 ENGINE ASSEMBLY AND ADJUSTMENTS CLUTCH AND PRIMARY DRIVE GEAR Clutch spring Thrust plate Pressure plate Conical spring washer Push plate Push rod #1 Clutch plate Ball Friction plate Push rod #2 Clutch damper Push lever axle Clutch boss Return spring Thrust washer Bearing Clutch housing...
  • Page 209 ENGINE ASSEMBLY AND ADJUSTMENTS BALANCER GEAR, PRIMARY DRIVE GEAR AND CLUTCH 1. Install: • Oil seal retainer • Spacer collar Oil Seal Retainer: 16 Nm (1.6 m•kg; 11 ft•lb) NOTE: Before installing the spacer collar greae the oil seal lip 2.
  • Page 210 ENGINE ASSEMBLY AND ADJUSTMENTS s WARNING Always use a new lock washer 5. Tighten: • Nut (Primary drive gear) • Nut (Balancer driven gear) Nut (Primary drive gear): 80 Nm (8.0 m•kg; 58 ft•lb) Nut (Balancer driven gear): 55 Nm (5.5 m•kg; 40 ft•lb) NOTE: Hold the rotor to tighten the nut (Primary drive gear)
  • Page 211 ENGINE ASSEMBLY AND ADJUSTMENTS 8. Install: • Push rod #2 • Ball • Conical spring washer • Thrust plate • Clutch housing • Thrust washer • Clutch boss • Lock washer • Nut (Clutch boss) s WARNING Always use a new lock washer NOTE: •...
  • Page 212 ENGINE ASSEMBLY AND ADJUSTMENTS 11. Install: • Friction plates • Clutch plates • Clutch damper Installation steps • Install the friction plate onto the clutch boss. • Install the clutch plate so as to locate the projection at #1. • Install the friction plate with the larger insi- de diameter onto the clutch boss.
  • Page 213 ENGINE ASSEMBLY AND ADJUSTMENTS NOTE: Tighten the bolts (pressure plate) in stage, using a crisscross pattern 14. Adjust: • Clutch mechanism free play Refer to the “CLUTCH MECHANISM ADJUSTMENT” section in chapter 3. 15. Install: • Gasket (Crankcase cover) • Dowel pins •...
  • Page 214 ENGINE ASSEMBLY AND ADJUSTMENTS CYLINDER HEAD AND CYLINDER Spark plug Cylinder head Cylinder head gasket Cylinder Cylinder gasket SPARK PLUG MANUFACTURER TYPE: BR9ES 20 Nm (2.0m • kg, 14ft•lb) PLUG GAP: 0.7~0.8mm (0.028~0.0012in) 22 Nm (2.2m • kg, 16ft•lb) CYLINDER HEAD WARRAGE LIMIT: 0.03mm(0.0012in) USE NEW ONE...
  • Page 215 ENGINE ASSEMBLY AND ADJUSTMENTS PISTON, CYLINDER AND CYLINDER HEAD 1. Install: • Bearing • Piston • Piston pin • Piston pin clips NOTE: • Apply engineoil tothe piston pin, bearings and piston skirts areas. • Make sure the arrow mark on the piston points towards the exhaust side of the cylinder.
  • Page 216 ENGINE ASSEMBLY AND ADJUSTMENTS 3. Install: • Dowel pins • Gasket <NEW> (Cylinder) s WARNING Always use a new gasket 4. Install: • Cylinder • Clutch cable guide NOTE: Install the cylinder with one hand while com- pressing the piston rings with the other hand 5.
  • Page 217 ENGINE ASSEMBLY AND ADJUSTMENTS 8. Install: • O-ring • Thermostatic valve • Gasket NOTE: Apply the lithium soap base grease to the O- ring s WARNING • Always use a new O-ring. • Always use a new gasket. 9. Install: •...
  • Page 218 ENGINE ASSEMBLY AND ADJUSTMENTS 11. Install: • Hoses (Inlet and outlet Union bolt: 8 Nm (0.8 m•kg, 5.8 ft•lb) REMOUNTING THE ENGINE Reverse the “ENGINE REMOVAL” procedure. Note the following points: 1. Install: • Engine assemb (to right side) • Mounting bolts Pivot shaft 90 Nm (9.0 m•kg, 65 ft•lb) Bolt...
  • Page 219 ENGINE ASSEMBLY AND ADJUSTMENTS 3. Bend the lock washer tab along the nut flats 4. Install: • Gasket (Crankcase cover) • Crankcase cover (Left) • Change pedal NOTE: Tighten the screws (Crankcase cover) in stage, using a crisscross pattern. Screw (Crankcase cover): 8 Nm (0.8 m•kg, 5.8 ft•lb) Bolt (Change pedal): 15 Nm (1.5 m•kg, 11 ft•lb)
  • Page 220 ENGINE ASSEMBLY AND ADJUSTMENTS 8. Connect: • Servomotor unit lead • Cables (Y.P.V.S.) (to power valve pulley) 9. Install: • Pulley (power valve) Bolt (Power valve pulley): 10Nm (1.0 m•kg, 7.2 ft•lb) 10. Adjust: • Y.P.V.S. cables Refer to the “Y.P.V.S. CABLE ADJUST- MENT”...
  • Page 221 ENGINE ASSEMBLY AND ADJUSTMENTS 13. Air bleeding: • Autolube pump Refer to the “AUTOLUBE PUMP AIR BLE- EDING” section in chapter 3. 14. Install: • Autolube pump cover Bolt (Autolube pump cover): 5 Nm (0.5 m•kg, 3.6 ft•lb) 15. Install: •...
  • Page 222 ENGINE ASSEMBLY AND ADJUSTMENTS 17. Fill: • Crankcase Refer to the “TRANSMISSION OIL REPLA- CEMENT” section in chapter 3. Total amount: 0,92L 5-60...
  • Page 223 COOL...
  • Page 225 COOL CHAPTER 6 COOLING SYSTEM WATER PUMP ……………………………………………………………………6-1 REMOVAL ………………………………………………………………………6-2 INSPECTION……………………………………………………………………6-4 INSTALLATION …………………………………………………………………6-4 THERMOSTATIC VALVE AND RADIATOR ……………………………………6-7 REMOVAL ………………………………………………………………………6-8 INSPECTION …………………………………………………………………6-10 INSTALLATION ………………………………………………………………6-11...
  • Page 226 COOL WATER PUMP COOLING SYSTEM WATER PUMP Impeller shaft Water pump housing cover Oil Seal Gasket Dowel pin Impeller shaft gear Drain bolt Plain washer Gasket Circlip 8 Nm (0.8 m • kg, 5.8 ft•lb) USE NEW ONE USE NEW ONE...
  • Page 227 COOL WATER PUMP REMOVAL NOTE: It is necessay to disassemble the water pump unless there is no abnormality such as exces- sive change in coolant temperature and/or dis- coloration of coolant or milky transmission oil. 1. Drain: • Transmission oil Refer to the “TRANSMISSION OIL REPLA- CEMENT”...
  • Page 228 COOL WATER PUMP 7. Remove: • Return spring • Bolt (Master cylinder) • Brake pedal • Crankcase cover 8. Remove: • Water outlet pipe • Housing cover (Water pump) • Gasket • Dowel pins 9. Remove: • Circlip • Plain washer •...
  • Page 229 COOL WATER PUMP EAS00472 CHECKING THE WATER PUMP 1. Check: • O-ring Damage/wear Replace. • oil seal Damage/wear Replace the water pump housing assembly. 2. Check: • impeller Cracks/damage/wear Replace the water pump housing assembly. • bearing Rough movement Replace the water pump housing assembly.
  • Page 230 COOL WATER PUMP 3. Install: • Housing cover (Water pump) • Water outlet pipe Screw (Crankcase cover): 8 Nm (0.8 m•kg, 5.8 ft•lb) Screw (Water Outlet Pipe): 8 Nm (0.8 m•kg, 5.8 ft•lb) CAUTION • Always use new gaskets • Always use a new O-ring 4.
  • Page 231 COOL WATER PUMP 6. Fill: • Crankcase Refer to the “TRANSMISSION OIL REPLA- CEMENT” section in chapter 3. Recommended Oil: SAE 10W30 type SE Motor Oil Periodic Oil Change: 0,75L 7. Fill: • Radiator Refer to the “COOLANT REPLACEMENT” section. Total amount: 0,92L 8.
  • Page 232 COOL THERMOSTATIC VALVE AND RADIATOR THERMOSTATIC VALVE AND RADIATOR Radiator assembly Hose (Carburetor warmer Inlet) Radiator cap Hose (Carburetor warmer Inlet) Inlet hose Thermostatic valve cover Coolant breather hose Gasket Outlet hose Thermostatic valve Gasket O-ring RADIATOR CAP OPENING PRESSURE: COOLANT CAPACITY: 75~105kPA 0.92L Including all routes...
  • Page 233 COOL THERMOSTATIC VALVE AND RADIATOR REMOVAL 1. Remove: • Side covers (Left and Right) • Seat • Exhaust pipe 2. Remove: • Radiator cover • Oil tank cover • Fuel tank Refer to the “CARBURETOR REMOVAL” section in chapter 7. 3.
  • Page 234 COOL THERMOSTATIC VALVE AND RADIATOR 4. Remove: • Radiator cap 5. Disconnect: • Breather hose (Radiator 6. Remove: • Inlet hose (Radiator) • Outlet hose (Radiator) 7. Remove: • Water outlet pipe • O-ring 8. Remove: • Radiator fin 9. Remove: •...
  • Page 235 COOL THERMOSTATIC VALVE AND RADIATOR 10. Remove: • Thermostatic valve cover • Gasket • Thermostatic valve • O-ring EAS00455 CHECKING THE RADIATOR 1. Check: • radiator fins Obstruction Clean. Apply compressed air to the rear of the radiator. Damage Repair or replace. NOTE: Straighten any flattened fins with a thin, flat- head screwdriver.
  • Page 236 COOL THERMOSTATIC VALVE AND RADIATOR a. Install the radiator cap tester and radiator cap tester adapter to the radiator cap. Radiator cap tester 90890-01325 Radiator cap tester adapter 90890-01352 b. Apply the specified pressure for ten seconds and make sure there is no drop in pressure.
  • Page 237 COOL THERMOSTATIC VALVE AND RADIATOR 2. Install: • Radiator Bolt(Radiator): 8 Nm (0.8 m·kg; 5.8 ft·lb) 3. Apply grease to the O-ring 4. Install: • O-ring • Water outlet pipe s WARNING Always use a new O-ring Screw (Water Outlet Pipe): 8 Nm (0.8 m·kg;...
  • Page 238 COOL THERMOSTATIC VALVE AND RADIATOR Inspection steps • Attach the Cooling System Tester to the radiator Radiator cap tester 90890-01325 • Apply 100kPa (1.0 kg/cm , 14psi) pressure. • Measure the indicated pressure with the gauge. 6-13...
  • Page 239 CARB...
  • Page 241 CARB CHAPTER 7 CARBURETOR CARBURETOR ……………………………………………………………………7-1 REMOVAL ………………………………………………………………………7-2 DISASSEMBLY …………………………………………………………………7-3 INSPECTION……………………………………………………………………7-4 ASSEMBLY ……………………………………………………………………7-6 INSTALLATION …………………………………………………………………7-8 ADJUSTMENT …………………………………………………………………7-9 REED VALVE ……………………………………………………………………7-10 REMOVAL ……………………………………………………………………7-11 DISASSEMBLY ………………………………………………………………7-11 INSPECTION …………………………………………………………………7-12 ASSEMBLY ……………………………………………………………………7-12 INSTALLATION ………………………………………………………………7-13...
  • Page 242 CARB CARBURETION CARBURETION CARBURETOR Pilot jet Throttle valve spring Needle jet Starter plunger Gasket Throttle stop screw Main jet Pilot air screw Needle valve assembly Throttle valve Float Needle set Drain screw Main Jet (M.J.) #210 Main Air Jet (M.A.J.) ø...
  • Page 243 CARB CARBURETOR REMOVAL NOTE: The following parts can be cleaned and ins- pected without disassembly • Throttle valve • Starter plunger • Throttle stop screw 1. Remove: • Side cover (Left and Right) • Seat • Radiator cover 2. Turn the fuel cock to “OFF” position. 3.
  • Page 244 CARB CARBURETOR 6. Disconnect: • Hoses • Oil delivery hose • Cooling hoses 7. Loosen: • Screw (carburetor joint) • Screw (air box) 8. Remove: • Carburetor top • Carburetor 9. Remove: • Cable holder • Throttle valve • Return spring DISASSEMBLY 1.
  • Page 245 CARB CARBURETOR 4. Remove: • Float pin • Float • Needle valve 5. Remove: • Valve seat • Main jet • Jet needle holder 6. Remove: • Throttle stop screw • Pilot air screw INSPECTION 1. Inspect: • Carburetor mixing chamber body Contamination Clean NOTE:...
  • Page 246 CARB CARBURETOR 3. Inspect: • Valve seat • Gasket • Needle valve NOTE: Always replace the needle valve and valve seat as a set. 4. Inspect: • Starter plunger Wear/Contamination Replace 5. Check: • Free movement Stick Replace Insert the throttle valve into the carburetor body and check for free movement.
  • Page 247 CARB CARBURETOR 10. Inspect: • Float Damage Replace 11. Inspect: • Main jet • Needle jet • Pilot jet Contamination Clean NOTE: Blow out the jets with compressed air ASSEMBLY Reverse the “DISASSEMBLY” procedures. Note the following points. CAUTION Before reassembling, wash all parts with clean gasoline 1.
  • Page 248 CARB CARBURETOR Measurement and adjustment steps: • Hold the carburetor in an upside down position. • Measure the distance from the mating sur- face on the float chamber (gasket removed) to the top of the float. CAUTION The float arm should be resting on the needle valve, but not compressing the needle valve.
  • Page 249 CARB CARBURETOR 7. Intall: • Throttle valve NOTE: Align the groove of the throttle valve with the projection of the carburetor body. INSTALLATION Reverse the “REMOVAL” procedures. Note the following points. 1. Install: • Carburetor assembly NOTE: Align the groove of the carburetor joint with the projection of the carburetor body.
  • Page 250 CARB CARBURETOR ADJUSTMENT Fuel level adjustment 1. Measure: • Fuel level Out of specification adjust Fuel level: 1.5~2.5mm (0.05~0.09in.) In the middle of the Float Chamber. Below the carburetor Body edge. Fuel level measurement and adjustment steps: • Place the motorcycle on a level surface. •...
  • Page 251 CARB REED VALVE REED VALVE Reed valve assembly Reed valve Stopper plate Gasket Carburetor joint Y.E.I.S. Chamber 10 Nm (1.0 m • kg, 7.2 ft•lb) 1 Nm (0.1 m • kg, 0.7 ft•lb) USE NEW ONE 7-10...
  • Page 252 CARB REED VALVE REMOVAL 1. Remove: • Carburetor Refer to the “CARBURETOR REMOVAL” section. 2. Remove: • Carburetor joint 3. Remove: • Reed valve assembly • Gasket DISASSEMBLY 1. Remove: • Y.E.I.S. chamber 2. Remove: • Reed valve stopper • Reed valve 7-11...
  • Page 253 CARB REED VALVE INSPECTION 1. Inspect: • Reed valve • Reed valve stopper Cracks/Damage Replace 2. Measure: • Reed valve bending limit Out of specification Replace. Reed valve Bending Limit: 0.5mm (0.02in) Surface plate 3. Measure: • Reed valve stopper height Out of specification Replace.
  • Page 254 CARB REED VALVE • Fit the reed valve stopper out with the corresponding cut on the reed valve. 2. Tighten: • Screws (Reed valve) Screws (Reed valve): 1 Nm (0.1 m·kg; 0.7 ft·lb) Use LOCTITE® NOTE: Tighten each screw gradually to avoid war- ping.
  • Page 255 ELEC...
  • Page 257 LIGHTING SYSTEM ……………………………………………………………8-16 CIRCUIT DIAGRAM …………………………………………………………8-16 TROUBLESHOOTING ………………………………………………………8-17 SIGNALING SYSTEM …………………………………………………………8-26 CIRCUIT DIAGRAM …………………………………………………………8-26 TROUBLESHOOTING ………………………………………………………8-27 COOLING SYSTEM ……………………………………………………………8-38 CIRCUIT DIAGRAM …………………………………………………………8-38 TROUBLESHOOTING ………………………………………………………8-39 YAMAHA POER VALVE SYSTEM ……………………………………………8-42 CIRCUIT DIAGRAM …………………………………………………………8-42 TROUBLESHOOTING ………………………………………………………8-43 METER ASSEMBLY ……………………………………………………………8-46 REMOVAL ……………………………………………………………………8-47 INSTALLATION ………………………………………………………………8-48...
  • Page 258 ELEC DT125RE CIRCUIT DIAGRAM ELECTRICAL DT125RE CIRCUIT DIAGRAM Black Chocolate W/R White/Red Dark green W/L White/Blue Orange Sky blue Y/R Yellow/Red Blue Brown G/R Green/Red Pink Blue/Yellow G/Y Green/Yellow Yellow B/Y Black/Yellow G/W Green/White Green B/W Black/White Br/W Brown/White White B/R black/Red L7R Blue/Red...
  • Page 259: Electrical Components

    ELEC ELECTRICAL COMPONENTS ELECTRICAL COMPONENTS(1) CDI Unit Thermo unit Servomotor Rectifier/Regulator Battery Ignition coil Fuse Main switch Neutral switch Ignition coil: Primary coil resistance: 0.23 Ω at 20 °C Secondary coil resistance: 7.9 kΩ at 20 °C...
  • Page 260 ELEC ELECTRICAL COMPONENTS ELECTRICAL COMPONENTS(2) Flasher relay Sidestand switch Conductor wire Brake switch Rectifier 2 Relay Oil gauge Horn Battery: Capacity: 12V 6Ah No maintenance...
  • Page 261: Checking Switch Continuity

    ELEC CHECKING SWITCH CONTINUTY EAS00730 CHECKING SWITCH CONTINUITY Check each switch for continuity with the poc- ket tester. If the continuity reading is incorrect, check the wiring connections and if necessary, replace the switch. CAUTION: Never insert the tester probes into the cou- pler terminal slots.
  • Page 262 ELEC CHECKING THE SWITCHES EAS00731 CHECKING THE SWITCHES Check each switch for damage or wear, proper Damage/wear Repair or replace. connections, and also for continuity between the Improperly connected Properly connect. terminals. Refer to “CHECKING SWITCH CON- Incorrect continuity reading Replace the TINUITY”.
  • Page 263 ELEC IGNITION SYSTEM IGNITION SYSTEM The circuit diagram showns the ignition system.
  • Page 264 ELEC IGNITION SYSTEM NOTE: For the color codes see the electric diagram Magneto CDI Battery Fuse Starter relay Starting engine Main switch C.D.I. Ignition coil · ·...
  • Page 265 ELEC IGNITION SYSTEM EAS00736 EAS00740 TROUBLESHOOTING 1. Spark plug • Check the condition of the spark plug. The ignition system fails to operate • Check the spark plug type. (no spark or intermittent spark). • Measure the spark plug gap. Refer to “CHECKING THE SPARK PLUG”...
  • Page 266 ELEC IGNITION SYSTEM EAS00744 • Connect the pocket tester (Ω x 1k) to the 3. Spark plug cap resistance ignition coil as shown. • Remove the spark plug cap from the spark plug lead. • Connect the pocket tester (“Ω x 1k” range) to the spark plug cap as shown.
  • Page 267 ELEC IGNITION SYSTEM EAS00749 EAS00750 5. Main switch 6. “ENGINE STOP” switch • Disconnect the main switch coupler and • Disconnect the “ENGINE STOP” switch lead from the wireharness (red). leads from the wireharness. • Connect the pocket tester (Ω 100) to the •...
  • Page 268 ELEC IGNITION SYSTEM EAS00748 7. source coil resistance 8. Pickup coil resistance • Disconnect the CDI magneto coupler • Disconnect the CDI magneto coupler from from the wireharness. the wire harness. • Connect the pocket tester (Ω 100) to the •...
  • Page 269 ELEC IGNITION SYSTEM EAS00752 EAS00751 Procedure (2) 2. Neutral switch 1. Sidestand switch • Disconnect the CDI magneto coupler from • Disconnect the sidestand switch leads the wireharness. from the wireharness. • Connect the pocket tester (Ω 100) to the •...
  • Page 271: Charging System

    ELEC CHARGING SYSTEM EAS00773 CHARGING SYSTEM CIRCUIT DIAGRAM Generator Battery Rectifier/regulator Main fuse 8-14...
  • Page 272 ELEC CHARGING SYSTEM EAS00774 EAS00775 TROUBLESHOOTING 3. Charging voltage • Connect the engine tachometer to the The battery is not being charged. spark plug lead. • Connect the pocket tester (DC 20 V) to the battery. 1. main fuse 2. battery Positive tester probe positive battery 3.
  • Page 273 ELEC LIGHTING SYSTEM EAS00780 LIGHTING SYSTEM CIRCUIT DIAGRAM Magento-CDI Headlight Rectifier/regulator Tail light Main switch Meter lights “LIGHTS” switch 8-16...
  • Page 274 ELEC LIGHTING SYSTEM EAS00781 TROUBLESHOOTING 1. Bulb • Remove the bulb. Any of the following fail to light: head- Refer to the “HEADLIGHT BULB REPLA- light, high beam indicator light, taillight, CEMENT” section in the chapter 3. auxiliary light or meter light. •...
  • Page 275 ELEC LIGHTING SYSTEM 2. Bulb socket 3. “LIGHTS” (Dimmer) switch • Disconnect the bulb socket leads from the • Connect the pocket tester (Ω 100) to the wire harness. bulbs terminals. • Install the bulb to the bulb socket. When turning “LIGHTS” (Dimmer) switch to •...
  • Page 276 ELEC LIGHTING SYSTEM EAS00787 4. Lighting voltage. 5. Wiring • Turn (Dimmer) switch to “LO”. • Check the entire lighting system’s wiring. • Connect the pocket tester (DC 20 V) to the Refer to “CIRCUIT DIAGRAM”. battery. • Is the lighting system’s wiring properly con- nected and without defects? Positive tester probe Green...
  • Page 277 ELEC LIGHTING SYSTEM TROUBLESHOOTING 1. Bulb Meter light does not come on • Remove the bulb. Refer to the “METER ASSEMBLY” section. • Connect the pocket tester (Ω 1) to the Check: bulbs terminals. 1. Meter light bulb 2. Meter light bulb socket Positive tester probe terminal 3.
  • Page 278 ELEC LIGHTING SYSTEM 2. Bulb socket • Disconnect the bulb socket lead and cou- pler from the wire harness. • Install the bulb to the bulb socket. • Connect the pocket tester (Ω 1) to the bulbs socket lead end and coupler. Positive tester probe Blue lead...
  • Page 279 ELEC LIGHTING SYSTEM TROUBLESHOOTING 1. Bulb Tail light/Auxiliary light do not come on • Remove the bulb. • Connect the pocket tester (Ω 1) to the bulb terminals. Check: 1. Tail/Brake light bulb/Auxiliary light bulb Positive tester probe terminal 2. Tail light bulb socket/Auxiliary light Negative tester probe terminal 3.
  • Page 280 ELEC LIGHTING SYSTEM 2. Bulb socket 3. Main switch • Disconnect the bulb socket and leads from • Disconnect the main switch coupler from the wire harness. the wire harness. • Install the bulb to the bulb socket. • Connect the pocket tester (Ω 1) to the bulbs socket lead end and coupler.
  • Page 281 ELEC LIGHTING SYSTEM EAS00787 4. Wiring • Check the entire lighting system’s wiring. Refer to “CIRCUIT DIAGRAM”. • Is the lighting system’s wiring properly con- nected and without defects? Properly connect or Check the condition repair the lighting of each of the ligh- system’s wiring.
  • Page 283: Signaling System

    ELEC SIGNAL SYSTEM EAS00793 SIGNALING SYSTEM CIRCUIT DIAGRAM Main switch Diode Tail/brake light Main fuse Horn switch Rear brake light switch Battery Horn Front brake light switch Neutral switch Turn switch Engine oil level switch Turn signal relay 8-26...
  • Page 284 ELEC SIGNAL SYSTEM EAS00794 TROUBLESHOOTING 3. Main switch • Disconnect the main switch coupler from Any of the following fail to light: flasher the wire harness. light, brake light or an indicator light do • Connect the pocket tester (Ω 1) to the main not come on and the horn fails to sound.
  • Page 285 ELEC SIGNAL SYSTEM 2. Bulb socket FLASHER LIGHT DOES NOT BRINK • Install the bulb to the sockets. • Disconnect the flahser light leads from the wire harness. 1. Bulb • Connect the pocket tester (Ω 1) to the flas- her light leads.
  • Page 286 ELEC SIGNAL SYSTEM 3. “TURN” switch 4. Voltage • Disconnect the “TURN” switch (Left hand- • Disconnect the flasher relay coupler lebar switch) coupler from the wire har- from the wire harness. ness. • Turn the main switch to “ON”. •...
  • Page 287 ELEC SIGNAL SYSTEM 2. Bulb socket BRAKE LIGH DOES NOT COME ON • Disconnect the bulb socket coupler from the wire harness. • Connect the pocket tester (Ω 1) to the bulb 1. Bulb socket leads. • Remove the bulb. Positive tester probe Yellow •...
  • Page 288 ELEC SIGNAL SYSTEM 3. Front brake switch 4. Rear brake switch • Disconnect the front brake switch coupler • Disconnect the front brake switch coupler from the wire harness. from the wire harness. • Connect the pocket tester (Ω 1) to the •...
  • Page 289 ELEC SIGNAL SYSTEM 2. Bulb socket “NEUTRAL” INDICATOR LIGHT DOES NOT COME ON • Disconnect the bulb socket coupler from the wire harness. • Connect the pocket tester (Ω 1) to the bulb 1. Bulb socket leads. • Remove the bulb. Positive tester probe Brown Refer to the “METER ASSEMBLY”...
  • Page 290 ELEC SIGNAL SYSTEM EAS00795 3. Neutral switch 4. Wiring • Disconnect the CDI magneto coupler from • Check the entire signal system’s wiring. the wire harness. Refer to “CIRCUIT DIAGRAM”. • Connect the pocket tester (Ω 1) to the neu- •...
  • Page 291 ELEC SIGNAL SYSTEM 2. Bulb socket “OIL” INDICATOR LIGHT DOES NOT COME ON • Disconnect the bulb socket coupler from the wire harness. • Connect the pocket tester (Ω 1) to the cou- 1. Bulb pler. • Remove the bulb. Positive tester probe Brown Refer to the “METER ASSEMBLY”...
  • Page 292 ELEC SIGNAL SYSTEM 3. Oil level switch (Diode) 4. Oil level switch • Disconnect the oil level switch from the • Connect the pocket tester (Ω 1) to the oil wire harness. level switch. • Connect the pocket tester (Ω 1) to the neu- tral switch coupler.
  • Page 293 ELEC SIGNAL SYSTEM 2. Voltage HORN DOES NOT SOUND, WHEN PUS- HING “HORN” SWITCH • Connect the pocket tester (DC20V) to the horn terminal. 1. “HORN” switch Positive tester probe Brown Terminal • Disconnect the “HORN” switch (Left hand- Negative tester probe Frame ground.
  • Page 294 ELEC SIGNAL SYSTEM 4. Horn • Disconnect the “pink” lead at the horn ter- minal. • Connect a jumper lead to the horn ter- minal and ground the jumper lead. • Does the horn sounds OK? Replace the horn. 5. Voltage •...
  • Page 295 ELEC COOLING SYSTEM EAS00807 COOLING SYSTEM CIRCUIT DIAGRAM Battery Main fuse Main switch Thermo switch 8-38...
  • Page 296 ELEC COOLING SYSTEM EAS00808 TROUBLESHOOTING 1. Fuse • Remove the fuse. • The radiator fan motor fails to turn. • Connect the pocket tester (Ω 1) to the fuse. • The water temperature gauge needle • Check the fuse for continuity. fails to move when the engine is warm.
  • Page 297 ELEC COOLING SYSTEM 3. Main switch 4. Thermo unit • Disconnect the main switch coupler from • Remove the thermo unit from the cylinder the wire harness. head. • Connect the pocket tester (Ω 1) to the main • Connect the pocket tester (Ω 1) to the ther- switch.
  • Page 298 ELEC COOLING SYSTEM EAS00795 5. Wiring • Check the entire signal system’s wiring. Refer to “CIRCUIT DIAGRAM”. • Is the signaling system’s wiring properly connected and without defects? Properly connect or Check the condition repair the signaling of each of the sig- system’s wiring.
  • Page 299 ELEC YAMAHA POWER VALVE SYSTEM YAMAHA POWER VALVE SYSTEM CIRCUIT DIAGRAM CDI Unit Battery Main switch Servomotor Main fuse 8-42...
  • Page 300 • Check the fuse for continuity. Check: • Is the fuse OK? 1. fuse 2. battery 3. main switch 4. servomotor operation 5. wiring connections (Yamaha Power Valve Replace the fuse. System) 6. servomotor and tachometer operation 2. Battery NOTE: • Check the battery condition.
  • Page 301 ELEC MOTOR 3. Main switch 4. Servomotor operation • Disconnect the main switch coupler • Disconnect servomotor coupler from the from the wire harness. wire harness. • Connect the pocket tester (Ω 1) to the main • Connect the battery leads to the servomo- switch.
  • Page 302 ELEC MOTOR 6. Servomotor and tachometer operation • Start the engine and increase revolution to about 7000rev/min. • Check servomotor and tachometer for operation. Pocket tester 90890-03112 • Is the servomotor OK? Replace the servo- motor. 8-45...
  • Page 303 ELEC METER ASSEMBLY METER ASSEMBLY Speedometer Meter bracket Bulb Stopper clip Bulb socket Washer Speedometer cable Damper collar Meter cushion 8-46...
  • Page 304 ELEC METER ASSEMBLY REMOVAL 1. Remove: • Headlight cover 2. Disconnect: • Headlight leads • Auxiliary light leads 3. Remove: • Band 4. Disconnect: • Speedometer cable 5. Disconnect: • Meter leads 6. Remove: • Meter assembly 8-47...
  • Page 305 ELEC METER ASSEMBLY 7. Remove: • Meter cushion • Meter lights • Leads CAUTION Do not remove the indicator bulbs sockets by pulling the leads INSTALLATION Reverse the “REMOVAL” procedure. Note the following points: 1. Install the meter lights, indicator lights and leads as shown.
  • Page 306 ELEC METER ASSEMBLY NOTE: Install the headlight lens unit onto the head- light stay by fitting the guide rubber pro- perly in the guide hole of the headlight unit. 3. Install: • Headlight cover 4. Adjust: • Headlight beam Refer to the “HEADLIGHT BEAM ADJUST- MENT”...
  • Page 307 TRBL SHTG...
  • Page 309 TRBL SHTG CHAPTER 9 TROUBLESHOOTING STARTING FAILURE / HARD STARTING ……………………………………9-1 FUEL SYSTEM …………………………………………………………………9-1 ELECTRICAL SYSTEM ………………………………………………………9-2 POOR IDLE SPEED PERFORMANCE ………………………………………9-3 POOR IDLE SPEED PERFORMANCE ………………………………………9-3 POOR MEDIUM AND HIGH SPEED PERFORMANCE ……………………9-3 FUEL SYSTEM …………………………………………………………………9-3 ELECTRICAL SYSTEM ………………………………………………………9-3 COMPRESSION SYSTEM ……………………………………………………9-4 Y.P.V.S.
  • Page 310: Troubleshooting

    TRBL STARTING FAILURE/HARD STARTING SHTG TROUBLESHOOTING NOTE: The following troubleshooting does not cover all the possible causes of trouble. It should be help- ful, however, as a guide to troubleshooting. Refeer to the relative procedure in this manual for ins- pection, adjustment and replacement of parts.
  • Page 311 TRBL TROUBLESHOOTING SHTG ELECTRICAL SYSTEM PROBABLE CAUSE • Spark plug • Improper plug gap • Worn electrodes • Wire between terminals broken • Improper heat range • Faulty spark plug cap • Ignition coil • Broken or shorted primary/secondary • Faulty spark plug lead •...
  • Page 312 TRBL TROUBLESHOOTING SHTG POOR IDLE SPEED PERFORMANCE POOR IDLE SPEED PERFORMANCE PROBABLE CAUSE • Carburetor • Improperly returned starter plunger • Clogged or loose pilot jet • Clogged pilot air passage • Improperly adjusted idle speed (throttle stop screw) • Improper throttle cable play •...
  • Page 313 TRBL TROUBLESHOOTING SHTG COMPRESSION SYSTEM PROBABLE CAUSE • Cylinder and cylinder head • Loose spark plug • Broken cylinder head gasket • Broken cylinder gasket • Loose cylinder head or cylinder • Worn, damaged or seized cylinder • Piston and piston ring •...
  • Page 314 TRBL TROUBLESHOOTING SHTG FAULTY GEAR SHIFTING HARD SHIFTING PROBABLE CAUSE • Clutch • Improperly adjusted clutch cable • Improperly adjusted push lever position • Improper engagement of push lever and push rod • Warped clutch plate • Swollen friction plate •...
  • Page 315 TRBL TROUBLESHOOTING SHTG CLUTCH DRAGGING PROBABLE CAUSE • Clutch • Improperly adjusted clutch cable • Improperly adjusted push lever position • Improper engagement of push lever and push rod • Warped clutch plate • Swollen friction plate • Broken clutch boss •...
  • Page 316 TRBL TROUBLESHOOTING SHTG INSTABLE HANDLING INSTABLE HANDLING PROBABLE CAUSE • Handlebars • Improperly installed or bent • Steering • Improperly installed handle crown • Bent steering shaft • Improperly installed steering shaft (Improperly tightened ringnut) • Damaged ball bearing (roller bearing or bearing race) •...
  • Page 317 TRBL TROUBLESHOOTING SHTG FAULTY SIGNAL AND LIGHTING SYSTEM HEADLIGHT DARK PROBABLE CAUSE • Improper bulb • Too many electric accesories • Hard charging (Broken charging coil and/or faulty rectifier/regualtor) • Incorrect connection • Improperly grounded • Poor contacts (main or “LIGHTS” switch) •...
  • Page 318 TRBL TROUBLESHOOTING SHTG FAULTY Y.P.V.S. PROBABLE CAUSE • Power valve • Seized or damaged power valve • Carbon build-up • Control cable • Improperly adjusted cable • Seized or discontinuous cable • Electrical parts • Insufficient battery capacity (improperly charged battery) •...
  • Page 319 DT125 WIRING DIAGRAM...
  • Page 320 COMPONENTS 1. CDI. Mag. 2. Rect./Regu. 3. Battery 4. Fuse 5. Starter Relay 6. Starting Motor 7. Main Sw. 8. Handle Sw. R 9. Starter Sw. 10. E/G Stop Sw. COLOR CODE 11. Clutch Sw. 12. Side Stand Sw. B ......Balck 13.

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Dt125x 2005Dtr 125

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