Yamaha YW125Y 2009 Service Manual

[Page 1] Yamaha 2009 YW125Y

2009 MOTORCYCLE SERVICE MANUAL Model : YW125Y_ 32SF819770E0 *32SF819770E0* ...

[Page 2] Yamaha 2009 YW125Y

EAS00000 YW125Y 2009 SERVICE MANUAL ©2008 by Yamaha Motor Taiwan Co., Ltd. First edition, July 2008 All rights reserved. Any reproduction or unauthorized use without the written permission of Yamaha Motor Taiwan Co., Ltd. is expressly prohibited. 0...

[Page 3] Yamaha 2009 YW125Y

EAS20070 IMPORTANT This manual was produced by the Yamaha Motor Taiwan Company, Ltd. 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...

[Page 4] Yamaha 2009 YW125Y

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 indivi...

[Page 5] Yamaha 2009 YW125Y

GEN INFO SPEC CHK ADJ ENG TRBL SHTG CHAS -+ ELEC 4 M B LS New M G COOL 12 34 56 78 90 qw er i s hj EAS00008 SYMBOLS The following symbols are not relevant to every vehicle. Symbols 1 to 9 indicate the subject of each chapter. 1 General information 2 ...

[Page 6] Yamaha 2009 YW125Y

EAS00011 TABLE OF CONTENTS GENERAL INFORMATION SPECIFICATIONS PERIODIC CHECKS AND ADJUSTMENTS CHASSIS ENGINE FUEL INJECTION SYSTEM ELECTRICAL SYSTEM TROUBLESHOOTING -+ GEN INFO SPEC CHK ADJ CHAS ENG FI ELEC TRBL SHTG 1 2 3 4 5 6 7 8 ...

[Page 7] Yamaha 2009 YW125Y

1-13 GEN INFO CHAPTER 1 GENERAL INFORMATION SCOOTER IDENTIFICATION................................................................... 1-1 VEHICLE IDENTIFICATION NUMBER............................................. 1-1 MODEL LABEL .......................

[Page 8] Yamaha 2009 YW125Y

1-1 GEN INFO SCOOTER IDENTIFICATION EAS00015 GENERAL INFORMATION SCOOTER IDENTIFICATION EAS00017 VEHICLE IDENTIFICATION NUMBER The vehicle identification number 1 is stamped into the frame. EAS00018 MODEL LABEL The model label 1 is affixed to the fra...

[Page 9] Yamaha 2009 YW125Y

1-2 GEN INFO EAS00896 FEATURES OUTLINE OF THE FI SYSTEM The main function of a fuel supply system is to provide fuel to the combustion chamber at the opti- mum air-fuel ratio in accordance with the engine operating conditions and the atmospheric temp...

[Page 10] Yamaha 2009 YW125Y

1-3 GEN INFO FEATURES EAS00897 FI SYSTEM The fuel pump delivers fuel to the fuel injector via the fuel filter. The pressure regulator maintains the fuel pressure that is applied to the fuel injector at only 250 kPa (2.5 kgf/cm 2 , 35.6 psi). Accordin...

[Page 11] Yamaha 2009 YW125Y

1-4 GEN INFO FEATURES O 2 sensor The O 2 sensor has been adopted to enable the catalyst to function at a high degree of efficiency by maintaining the air-fuel mixture near the stoichiometric ratio (14.7:1). This sensor, which is a zirconia type, ut...

[Page 12] Yamaha 2009 YW125Y

1-5 GEN INFO IMPORTANT INFORMATION EAS00020 IMPORTANT INFORMATION PREPARATION FOR REMOVAL AND DISAS- SEMBLY 1. Before removal and disassembly, remove all dirt, mud, dust and foreign material. 2. Use only the proper tools and cleaning equipment. Refer...

[Page 13] Yamaha 2009 YW125Y

1-6 GEN INFO IMPORTANT INFORMATION EAS00023 LOCK WASHERS/PLATES AND COTTER PINS After removal, replace all lock washers/plates 1 and cotter pins. After the bolt or nut has been tightened to specification, bend the lock tabs along a flat of the bolt ...

[Page 14] Yamaha 2009 YW125Y

1-7 GEN INFO IMPORTANT INFORMATION EAS00021 EQUIPMENT PREPARATION Turn Rivet (Turn type) Assembly status of the turn rivet(turn type). Dissembling 1. Press center pin1 inward to release the lock. 2. Remove the push rivet main body2. Assembling 1. Res...

[Page 15] Yamaha 2009 YW125Y

1-8 GEN INFO CHECKING THE CONNECTIONS EAS00026 CHECKING THE CONNECTIONS Check the leads, couplers, and connectors for stains, rust, moisture, etc. 1. Disconnect: 8lead 8coupler 8connector 2. Check: 8lead 8coupler 8connector Moisture J Dry with an air...

[Page 16] Yamaha 2009 YW125Y

1-9 GEN INFO Tool NO. Tool name / Function Illustration 90890-01085 (M8) YU-01083-2 90890-01084 YU-01083-3 90890-01235 YU-01235 90890-01268 YU-01268 90890-01304 YU-01304 90890-01337 YM-33285 90890-01311 YM-08035-A 90890-01326 YM-01326 90890-01294 YM-...

[Page 17] Yamaha 2009 YW125Y

1-10 GEN INFO Tool NO. Tool name / Function Illustration SPECIAL TOOLS 90890-01189 YM-01189 90890-01367 YM-A9409-7 90890-01368 YM-A9409-4 90890-01384 YM-33299 90890-01403 YU-A9472 90890-01701 YS-01880-A 90890-03079 YM-34483 90890-03081 YU-33223 90890...

[Page 18] Yamaha 2009 YW125Y

1-11 GEN INFO Tool NO. Tool name / Function Illustration SPECIAL TOOLS 90890-03141 YU-03141 90890-04101 90890-04019 YM-04019 90890-04108 YM-04108 90890-04116 YM-04116 90890-04117 YM-04117 90890-04118 YM-04118 90890-06754 YM-34487 90890-03182 YU-03182...

[Page 19] Yamaha 2009 YW125Y

1-12 GEN INFO SPECIAL TOOLS Tool NO. Tool name / Function Illustration 90890-85505 ACC-11001-05-01 Yamaha bond NO.1215 Sealant (Quick Gasket ® ) This sealant (bond) is used to apply on crankcase mating surfaces. ...

[Page 20] Yamaha 2009 YW125Y

2-32 SPEC CHAPTER 2 SPECIFICATIONS GENERAL SPECIFICATIONS ................................................................. 2-1 ENGINE SPECIFICATIONS ..................................................................... 2-2 CHASSIS SPECIFICATIONS......

[Page 21] Yamaha 2009 YW125Y

2-1 SPEC SPECIFICATIONS GENERAL SPECIFICATIONS Item Standard Limit GENERAL SPECIFICATIONS Model Code 32S1 (USA) … 32S2 (CAN) … Dimensions Overall length 1910mm (75.2in) … Overall width 765mm (30.1in) … Overall height 1110mm (43.7in) … Seat ...

[Page 22] Yamaha 2009 YW125Y

2-2 SPEC ENGINE SPECIFICATIONS Item Standard Limit ENGINE SPECIFICATIONS Engine Engine type Air-cooled, 4-stroke, SOHC … Displacement 0.125L (125cm 3 , 7.63cu-in) … Cylinder arrangement Forward inclined … single cylinder Bore × stroke 52.4 �...

[Page 23] Yamaha 2009 YW125Y

2-3 SPEC Item Standard Limit ENGINE SPECIFICATIONS Oil filter Oil filter type Wire mesh … Oil pump Oil pump type Trochoid … Inner rotor to outer rotor tip clearance 0.15mm (0.006in) or less 0.23mm (0.009in) Outer rotor to pump housing clearance 0...

[Page 24] Yamaha 2009 YW125Y

2-4 SPEC Item Standard Limit ENGINE SPECIFICATIONS A B A B Camshaft Drive system Chain drive (left) … Intake camshaft lobe dimensions Measurement A 25.267 ~ 25.367mm 25.167mm (0.995 ~ 0.999in) (0.991in) Measurement B 21.069 ~ 21.169mm 20.969mm (0.8...

[Page 25] Yamaha 2009 YW125Y

2-5 SPEC Item Standard Limit B C D A Head Diameter Face Width Seat Width Margin Thickness ENGINE SPECIFICATIONS Timing chain Model/number of links Morse 92RH2005/94 … Tensioning system Automatic … Valve, valve seats, valve guides Valve clearance ...

[Page 26] Yamaha 2009 YW125Y

2-6 SPEC ENGINE SPECIFICATIONS Item Standard Limit Valve stem to valve guide clearance Intake 0.015 ~ 0.042mm 0.08mm (0.0006 ~ 0.0017in) (0.0031in) Exhaust 0.030 ~ 0.057mm 0.1mm (0.0012 ~ 0.0022in) (0.0039in) Valve stem runout … 0.01mm (0.0004 in) ...

[Page 27] Yamaha 2009 YW125Y

2-7 SPEC Item Standard Limit ENGINE SPECIFICATIONS Valve springs Free length Intake 41.88mm (1.649in) 39.786mm (1.566in) Exhaust 41.88mm (1.649in) 39.786mm (1.566in) Installed length (valve closed) Intake 30mm (1.18in) … Exhaust 30mm (1.18in) … C...

[Page 28] Yamaha 2009 YW125Y

2-8 SPEC Item Standard Limit H D ENGINE SPECIFICATIONS T B B T Piston Piston-to-cylinder clearance 0.010 ~ 0.035mm 0.15mm (0.0004 ~ 0.0014in) (0.0059in) Diameter D 52.375 ~ 52.390mm … (2.0620 ~ 2.0626in) Height H 7.0mm (0.28in) … Piston pin bo...

[Page 29] Yamaha 2009 YW125Y

2-9 SPEC ENGINE SPECIFICATIONS Item Standard Limit B T Oil ring Dimensions (B × T) 2.0 × 2.5mm … (0.0787 × 0.0984in) End gap (installed) 0.2 ~ 0.7mm … (0.0079 ~ 0.0276in) Ring side clearance 0.04 ~ 0.12mm … (0.0016 ~ 0.0047in) ...

[Page 30] Yamaha 2009 YW125Y

2-10 SPEC Item Standard Limit ENGINE SPECIFICATIONS Rocker arm/rocker arm shaft Rocker arm inside diameter 10.000 ~ 10.015mm … (0.3937 ~ 0.3943in) Rocker arm shaft outside diameter 9.981 ~ 9.991mm … (0.3930 ~ 0.3933in) Arm-to-shaft clearance 0.00...

[Page 31] Yamaha 2009 YW125Y

2-11 SPEC Item Standard Limit ENGINE SPECIFICATIONS Transmission Transmission type V-belt automatic … Primary reduction system Helical gear … Primary reduction ratio 40/15 (2.667) … Secondary reduction system Spur gear … Secondary reduction r...

[Page 32] Yamaha 2009 YW125Y

2-12 SPEC CHASSIS SPECIFICATIONS CHASSIS SPECIFICATIONS Item Standard Limit Frame Frame type Steel tube underbone … Caster angle 27° … Trail 90mm (3.54in) … Front wheel Wheel type Cast wheel … Rim Size J12 × MT2.75 … Material Aluminum …...

[Page 33] Yamaha 2009 YW125Y

2-13 SPEC Item Standard Limit CHASSIS SPECIFICATIONS Rear tire Tire type Tubeless … Size 130/70-12 56L … Model (manufacturer) K761 (KENDA) … Tire pressure (cold) 0 ~ 90kg (0 ~ 198lb) 200kPa (2.0kgf/cm², 29psi) … 90kg (198lb)~ maximum load 22...

[Page 34] Yamaha 2009 YW125Y

2-14 SPEC CHASSIS SPECIFICATIONS Item Standard Limit Front suspension Suspension type Telescopic … Front fork type Coil spring/oil damper … Front fork travel 90mm (3.54in) … Spring Free length 252.1mm (9.93in) 247mm (9.72in) Installed length 23...

[Page 35] Yamaha 2009 YW125Y

2-15 SPEC Item Standard Limit ELECTRICAL SPECIFICATIONS ELECTRICAL SPECIFICATIONS System voltage 12V … Ignition system Ignition system type Transistorized coil ignition … Ignition timing 5° BTDC at 1800r/min … Advancer type Digital … Pickup ...

[Page 36] Yamaha 2009 YW125Y

2-16 SPEC ELECTRICAL SPECIFICATIONS Item Standard Limit Electric starting system System type Constant mesh … Starter motor Model (manufacturer) 5S9 00 (T-MORIC) … Suction voltage 12V … Power output 0.35kW … Brushes Overall length 10.0mm (0....

[Page 37] Yamaha 2009 YW125Y

2-17 SPEC ELECTRICAL SPECIFICATIONS Item Standard Limit Fuel sender Model (manufacturer) 5S9 (AISAN) … Sender unit resistance-full 4 ~ 10Ω … Sender unit resistance-empty 90 ~ 100Ω … Fuel level gauge Gauge type (manufacture) Analog (CHAOLONG) ...

[Page 38] Yamaha 2009 YW125Y

2-18 SPEC EAS00030 GENERAL TIGHTENING TORQUE SPECIFICATIONS This chart specifies tightening torques for stan- dard fasteners with a standard ISO thread pitch. Tightening torque specifications for spe- cial components or assemblies are provided for e...

[Page 39] Yamaha 2009 YW125Y

2-19 SPEC Part to be tightened Part name Thread size Q ’ ty Tightening torque Remarks TIGHTENING TORQUES 4 TIGHTENING TORQUES ENGINE Crankcase (left and right) together tightening. Cylinder head and cylinder Spark plug Cylinder head (timing chain s...

[Page 40] Yamaha 2009 YW125Y

2-20 SPEC TIGHTENING TORQUES Remarks Cylinder head tightening sequence Plate (V-belt guide) Idle gear plate Plate Clutch housing Primary fixed sheave Starter motor AC magneto rotor Stator coil Crankshaft position sensor Ignition coil O 2 sensor Engi...

[Page 41] Yamaha 2009 YW125Y

2-21 SPEC Part to be tightened Thread size Tightening torque Remarks TIGHTENING TORQUES CHASSIS LT ft•lbf Nm m•kgf Frame and engine bracket 2 Engine bracket 2, compression rod and engine Compression rod and frame Sidestand (bolt and stand) Sidest...

[Page 42] Yamaha 2009 YW125Y

2-22 SPEC TIGHTENING TORQUES TIP 1. First, tighten the ring nut (lower) approximately 38Nm (3.8m • kgf, 27.5ft • lbf) by using the torque wrench, then loosen the ring nut 1/4 turn. 2. Second, tighten the ring nut (lower) approximately 14Nm (1.4m...

[Page 43] Yamaha 2009 YW125Y

2-23 SPEC Lubrication Point Lubricant LS LS M 4 4 4 4 4 4 4 4 4 4 M LUBRICATION POINTS AND LUBRICANT TYPES EAS00031 LUBRICATION POINTS AND LUBRICANT TYPES ENGINE M 4 4 Oil seal lips Bearings O-rings (except V-belt drive unit) O-rings (fuel injector) ...

[Page 44] Yamaha 2009 YW125Y

2-24 SPEC BEL-RAY asembly lube ® BEL-RAY asembly lube ® Yamaha bond NO.1215 Lubrication Point Lubricant LUBRICATION POINTS AND LUBRICANT TYPES G G Main and drive axle serration (sprocket) Drive axle taper rollor bearing Transmission bearing Seconda...

[Page 45] Yamaha 2009 YW125Y

2-25 SPEC LUBRICATION POINTS AND LUBRICANT TYPES Lubrication Point Lubricant LS LS LS LS LS LS LS EAS00032 CHASSIS LS Engine mounting bolt Steering bearing and bearing races (upper and lower) Throttle grip inner surface and throttle cables Rear brake...

[Page 46] Yamaha 2009 YW125Y

2-26 SPEC CABLE ROUTING EAS00035 CABLE ROUTING 1 Connector cover 2 Horn 3 Front bracket 4 Starting circuit cut-off relay 5 Turn signal relay 6 Headlight relay 7 ECU lead 8 Turn signal relay lead 9 Main switch 0 Horn lead q Main switch lead w Rectifie...

[Page 47] Yamaha 2009 YW125Y

2-27 SPEC CABLE ROUTING E Headlight relay lead passes by the right side of inner fender rib. F Start relay sub lead to forward. G Orientation: white tape. H Totally cover the terminal after locking. I Torque: 4Nm (0.4m • kgf, 2.9ft • lbf). J Star...

[Page 48] Yamaha 2009 YW125Y

2-28 SPEC CABLE ROUTING 1 Rectifier/regulator 2 Body earth lead 3 Horn 4 ECU 5 Headlight lead 6 Turn signal relay 7 Horn lead 8 Rectifier/regulator lead 9 Brake hose holder 3 0 Brake hose holder 1 q Fuel hose w Pipe 3 e Roll over valve r Pipe 4 t Rea...

[Page 49] Yamaha 2009 YW125Y

2-29 SPEC CABLE ROUTING 1 Plain washer 2 Lean angle cut-off switch 3 Lean angle cut-off switch lead 4 FI diagnostic tool 5 Hight tension cord 6 Fuel pump lead 7 Engine temperature sensor lead 8 Fuel injector lead 9 Clamp (90464-13800) 0 Starter motor...

[Page 50] Yamaha 2009 YW125Y

2-30 SPEC CABLE ROUTING F Ignition coil lead passes under the cross tube. G Pass the throttle cable assembly through wire guide. H Locate the white tape of wire harness in the holder. I Clamp (90464-10800) the O 2 sensor lead. J Clamp (90464-25803) ...

[Page 51] Yamaha 2009 YW125Y

2-31 SPEC CABLE ROUTING 1 Rear brake cable 2 Speedometer 3 Front master cylinder 4 Brush guard (right) 5 Turn signal light (right) 6 Throttle cable assembly 7 Speedometer cable 8 Turn signal light (left) 9 Brush guard (left) 0 Handlebar bracket q Cla...

[Page 52] Yamaha 2009 YW125Y

3-59 CHK ADJ CHAPTER 3 PERIODIC CHECKS AND ADJUSTMENTS INTRODUCTION....................................................................................... 3-1 PERIODIC MAINTENANCE AND ADJUSTMENT ................................. 3-1 Periodic mainten...

[Page 53] Yamaha 2009 YW125Y

3-60 CHK ADJ CHECKING THE TIRES ..................................................................3-43 CHECKING THE WHEELS..............................................................3-46 CHECKING AND LUBRICATING THE CABLES.............................

[Page 54] Yamaha 2009 YW125Y

3-1 CHK ADJ EAS00036 PERIODIC CHECKS AND ADJUSTMENTS INTRODUCTION This chapter includes all information necessary to perform recommended checks and adjustments. If followed, these preventive maintenance procedures will ensure more reliable vehicle op...

[Page 55] Yamaha 2009 YW125Y

3-2 CHK ADJ PERIODIC MAINTENANCE AND ADJUSTMENT NO. ITEM ROUTINE INITIAL ODOMETER READING 1000 km (600 mi) or 1 month 4000 km (2000 mi) or 6 months 7000 km (4000 mi) or 12 months 10000 km (6000 mi) or 18 months 13000 km (8000 mi) or 24 months 16...

[Page 56] Yamaha 2009 YW125Y

3-3 CHK ADJ EAUT2710 TIP 8 Air filter and V-belt filter • This model’s air filter is equipped with a disposable oil-coated paper element, which must not be cleaned with compressed air to avoid damaging it. • The air filter element needs to be r...

[Page 57] Yamaha 2009 YW125Y

3-4 CHK ADJ EAS00038 COVER AND PANEL SEAT AND TRUNK RemarksOrder Job/Part Q’ty 1 2 3 4 5 6 7 1 1 1 1 1 1 1 Remove the parts in the order listed. For installation, reverse the removal pro- cedure. COVER AND PANEL Removing the seat and trunk Seat Fue...

[Page 58] Yamaha 2009 YW125Y

3-5 CHK ADJ COVER AND PANEL FOOTREST BOARD RemarksOrder Job/Part Q’ty 1 2 3 4 5 6 7 1 1 1 1 1 4 Remove the parts in the order listed. NOTICE First, disconnect the negative battery lead, and then the positive battery lead. After installing the b...

[Page 59] Yamaha 2009 YW125Y

3-6 CHK ADJ COVER AND PANEL RemarksOrder Job/Part Q’ty TIP While installing, the fuse box should be installed to the correct position. For installation, reverse the removal pro- cedure. 8 Footrest board 1 1 5 4 6 3 7 2 8 7Nm (0.7 m•kgf, 5.1 ft•...

[Page 60] Yamaha 2009 YW125Y

3-7 CHK ADJ 1 23Nm (2.3 m•kgf, 16.6 ft•lbf) 4 5 2 3 9Nm (0.9 m•kgf, 6.5 ft•lbf) 14Nm (1.4 m•kgf, 10.1 ft•lbf) 7Nm (0.7 m•kgf, 5.1 ft•lbf) 7Nm (0.7 m•kgf, 5.1 ft•lbf) LEG SHIELD 1 ASSEMBLY AND LEG SHIELD 2 RemarksOrder Job/Par...

[Page 61] Yamaha 2009 YW125Y

3-8 CHK ADJ COVER AND PANEL RemarksOrder Job/Part Q’ty Disassembling the leg shield 1 as- sembly Panel Headlight cover Headlight assembly Panel (leg shield 1) Leg shield 1 1 2 3 4 5 1 1 1 1 1 Remove the parts in the order listed. For assembly, reve...

[Page 62] Yamaha 2009 YW125Y

3-9 CHK ADJ ADJUSTING THE VALVE CLEARANCE EAS00049 ENGINE ADJUSTING THE VALVE CLEARANCE The following procedure applies to all of the valves. TIP 8 Valve clearance adjustment should be made on a cold engine, at room temperature. 8 When the valve clea...

[Page 63] Yamaha 2009 YW125Y

3-10 CHK ADJ 3 2 1 ADJUSTING THE VALVE CLEARANCE c. Align the TDC mark c on the AC magneto rotor with the stationary pointer d on the crankcase. d. Measure the valve clearance with a thick- ness gauge. Out of specification J Adjust. ▲▲▲▲▲�...

[Page 64] Yamaha 2009 YW125Y

3-11 CHK ADJ ADJUSTING THE VALVE CLEARANCE e. Measure the valve clearance again. f. If the valve clearance is still out of specifi- cation, repeat all of the valve clearance ad- justment steps until the specified clearance is obtained. ▲▲▲▲�...

[Page 65] Yamaha 2009 YW125Y

3-12 CHK ADJ 1 CHECKING THE ENGINE IDLING SPEED EAS00054 CHECKING THE ENGINE IDLING SPEED TIP Prior to checking the engine idling speed, the air filter element should be clean, and the engine should have adequate compression. 1. Start the engine and ...

[Page 66] Yamaha 2009 YW125Y

3-13 CHK ADJ a 1 2 b a ADJUSTING THE THROTTLE CABLE FREE PLAY EAS00056 ADJUSTING THE THROTTLE CABLE FREE PLAY TIP Prior to adjusting the throttle cable free play, the engine idling speed should be checked properly. 1. Check: 8throttle cable free play...

[Page 67] Yamaha 2009 YW125Y

3-14 CHK ADJ 1 a b ADJUSTING THE SEAT SPRING FORCE ADJUSTING THE SEAT SPRING FORCE TIP When open the seat and seat will not fold up automatically, adjust the spring force. 1. Remove: 8seat 8upper cover 2. Adjust: 8screw 1 Direction a Spring force is ...

[Page 68] Yamaha 2009 YW125Y

3-15 CHK ADJ CHECKING THE SPARK PLUG EAS00060 CHECKING THE SPARK PLUG 1. Remove: 8battery box cover 8front cover Refer to “COVER AND PANEL”. 2. Disconnect: 8spark plug cap WARNING Remove the spark plug cap, the engine is extremely hot. 3. Remove:...

[Page 69] Yamaha 2009 YW125Y

3-16 CHK ADJ CHECKING THE SPARK PLUG 8. Install: 8spark plug 13Nm(1.3m • kgf, 9.4ft • lbf) TIP Before installing the spark plug, clean the spark plug and gasket surface. 9. Connect: 8spark plug cap 10. Install: 8front cover 8battery box cover Ref...

[Page 70] Yamaha 2009 YW125Y

3-17 CHK ADJ 2 1 CHECKING THE IGNITION TIMING EAS00062 CHECKING THE IGNITION TIMING TIP Prior to checking the ignition timing, check the wiring connections of the entire ignition system. Make sure all connections are tight and free of corrosion. 1. R...

[Page 71] Yamaha 2009 YW125Y

3-18 CHK ADJ CHECKING THE IGNITION TIMING Engine idling speed 1700 ~ 1900r/min b. Check that the mark a on the AC magneto rotor is within the firing range b on the crankcase. Incorrect firing range J Check the ignition system. TIP The ignition timin...

[Page 72] Yamaha 2009 YW125Y

3-19 CHK ADJ 1 MEASURING THE COMPRESSION PRESSURE EAS00067 MEASURING THE COMPRESSION PRES- SURE TIP Insufficient compression pressure will result in a loss of performance. 1. Measure: 8valve clearance Out of specification J Adjust Refer to “ADJUSTI...

[Page 73] Yamaha 2009 YW125Y

3-20 CHK ADJ MEASURING THE COMPRESSION PRESSURE Compression pressure (with oil applied into the cylinder) Reading Higher than without oil Same as without oil Diagnosis Piston ring(s) wear or damage J Repair. Piston, valves, cylinder head gasket or p...

[Page 74] Yamaha 2009 YW125Y

3-21 CHK ADJ MEASURING THE COMPRESSION PRESSURE T R . . 8. Remove: 8compression gauge 9. Install: 8spark plug 13Nm(1.3m • kgf, 9.4ft • lbf) 10. Connect: 8spark plug cap 11. Install: 8front cover 8battery box cover Refer to “COVER AND PANEL�...

[Page 75] Yamaha 2009 YW125Y

3-22 CHK ADJ 3. Check: 8engine oil level The engine oil level should be between the minimum level mark a and maximum level mark b. Below the minimum level mark J Add the recommended engine oil to the proper level. Recommended engine oil type SAE20W-4...

[Page 76] Yamaha 2009 YW125Y

3-23 CHK ADJ 1 2 143 2 1 CHANGING THE ENGINE OIL T R . . T R . . EAS00076 CHANGING THE ENGINE OIL 1. Start the engine, warm it up for several min- utes, and then turn it off. 2. Place a container under the engine oil drain bolt. 3. Remove: 8eng...

[Page 77] Yamaha 2009 YW125Y

3-24 CHK ADJ 1 CHANGING THE ENGINE OIL Quantity Total amount 0.85 ~ 0.95L (0.9 ~ 1.0 US qt, 0.75 ~ 0.84 Imp. qt) Periodic oil change 0.80 ~ 0.90L (0.87 ~ 0.98 US qt, 0.74 ~ 0.83 Imp. qt) 8. Install: 8engine oil filler cap 9. Start the engine, warm it...

[Page 78] Yamaha 2009 YW125Y

3-25 CHK ADJ 1 2 1 CHANGING THE TRANSMISSION OIL T R . . CHANGING THE TRANSMISSION OIL 1. Stand the scooter on a level surface. TIP 8 Stand the scooter on a suitable stand. 8 Make sure that the scooter upright. 2. Start the engine, warm it up for...

[Page 79] Yamaha 2009 YW125Y

3-26 CHK ADJ MEASURING THE ENGINE OIL PRESSURE EAS00077 MEASURING THE ENGINE OIL PRESSURE 1. Check: 8engine oil level Below the minimum level mark J Add the recommended engine oil to the proper level. Refer to”CHECKING THE ENGINE OIL LEVEL”. 2. S...

[Page 80] Yamaha 2009 YW125Y

3-27 CHK ADJ MEASURING THE ENGINE OIL PRESSURE T R . . c. Start the engine after solving the problem(s) and check the engine oil pressure again. ▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲ 7. Tighten: 8engine temperature...

[Page 81] Yamaha 2009 YW125Y

3-28 CHK ADJ 1 2 1 CLEANING THE AIR FILTER ELEMENT EAS00086 CLEANING THE AIR FILTER ELEMENT 1. Remove: 8air filter case cover 1 8air filter element 2 2. Clean: 8air filter element 1 Apply compressed air to the outer sur- face of the air filter elemen...

[Page 82] Yamaha 2009 YW125Y

3-29 CHK ADJ 1 2 EAS00090 CLEANING THE V-BELT CASE AIR FILTER ELEMENT 1. Remove: 8V-belt case cover 8V-belt case air filter guide 1 8V-belt case air filter element 2 2. Clean: 8V-belt case air filter element (with solvent) TIP After cleaning, careful...

[Page 83] Yamaha 2009 YW125Y

3-30 CHK ADJ 2 1 CHECKING THE THROTTLE BODY JOINT AND INTAKE MANIFOLD/CHECKING THE FUEL HOSE EAS00094 CHECKING THE THROTTLE BODY JOINT AND INTAKE MANIFOLD 1. Remove: 8seat 8trunk 8battery box cover 8front cover Refer to “COVER AND PANEL”. 2. Remo...

[Page 84] Yamaha 2009 YW125Y

3-31 CHK ADJ 1 1 2 EAS00098 CHECKING THE BREATHER HOSES 1. Remove: 8seat 8trunk 8battery box cover 8front cover Refer to “COVER AND PANEL”. 2. Check: 8crankcase breather hose 1 8transmission case breather hose 2 Cracks/damage J Replace. Loose con...

[Page 85] Yamaha 2009 YW125Y

3-32 CHK ADJ 2 1 3 4 5 CHECKING THE EXHAUST SYSTEM EAS00099 CHECKING THE EXHAUST SYSTEM The following procedure applies to all of the muffler and gasket. 1. Remove: 8O 2 sensor coupler 8muffler Refer to “REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM...

[Page 86] Yamaha 2009 YW125Y

3-33 CHK ADJ 1 2 1 1 CHECKING THE CANISTER AND ROLL OVER VALVE CHECKING THE CANISTER AND ROLL OVER VALVE The following procedure applies to all of the can- ister and roll over valve. 1. Remove: 8seat 8trunk Refer to “COVER AND PANEL”. 2. Check: 8...

[Page 87] Yamaha 2009 YW125Y

3-34 CHK ADJ CHECKING THE CANISTER AND ROLL OVER VALVE 7. Check: 8roll over valve ▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼ a. Remove the roll over valve. b. Put roll over valve with the vertical angle. c. Connect the hose...

[Page 88] Yamaha 2009 YW125Y

3-35 CHK ADJ 1 CHECKING THE FRONT BRAKE/ADJUSTING THE REAR BRAKE EAS00114 ADJUSTING THE REAR BRAKE 1. Check: 8brake lever free play a Out of specification J Adjust. Brake lever free play 10 ~ 20mm (0.39 ~ 0.79in) EAS00108 CHASSIS CHECKING THE FRONT B...

[Page 89] Yamaha 2009 YW125Y

3-36 CHK ADJ EAS00116 CHECKING THE BRAKE FLUID LEVEL 1. Stand the scooter on a level surface. TIP 8 Place the scooter on a suitable stand. 8 Make sure the scooter is upright. CHECKING THE BRAKE FLUID LEVEL 2. Check: 8brake fluid level Below the minim...

[Page 90] Yamaha 2009 YW125Y

3-37 CHK ADJ 1 1 1 2 CHECKING THE FRONT BRAKE PADS/CHECKING THE REAR BRAKE SHOES/CHECKING THE FRONT BRAKE HOSE EAS00117 CHECKING THE FRONT BRAKE PADS The following procedure applies to all of the brake pads. 1. Operate the brake. 2. Check: 8front bra...

[Page 91] Yamaha 2009 YW125Y

3-38 CHK ADJ 1 2 EAS00133 BLEEDING THE HYDRAULIC BRAKE SYS- TEM WARNING Bleed the hydraulic brake system whenever: 88 88 8 the system is disassembled. 88 88 8 a brake hose is loosened, disconnected or replaced. 88 88 8 the brake fluid level is very l...

[Page 92] Yamaha 2009 YW125Y

3-39 CHK ADJ BLEEDING THE HYDRAULIC BRAKE SYSTEM TIP Loosening the bleed screw will release the pres- sure and cause the brake lever to contact the throttle grip. h. Tighten the bleed screw and then release the brake lever. i. Repeat steps (e) to (h)...

[Page 93] Yamaha 2009 YW125Y

3-40 CHK ADJ 5 CHECKING AND ADJUSTING THE STEERING HEAD EAS00148 CHECKING AND ADJUSTING THE STEER- ING HEAD 1. Stand the scooter on a level surface. WARNING Securely support the scooter so that there is no danger of it falling over. TIP Place the sco...

[Page 94] Yamaha 2009 YW125Y

3-41 CHK ADJ 6 CHECKING AND ADJUSTING THE STEERING HEAD T R . . Lower ring nut (initial tightening torque) 38Nm (3.8m • kgf, 27.5ft • lbf) c. Losen the lower ring nut completely and then tighten it to specification with a steering nut wrench. W...

[Page 95] Yamaha 2009 YW125Y

3-42 CHK ADJ CHECKING THE FRONT FORK EAS00151 CHECKING THE FRONT FORK 1. Stand the scooter on a level surface. WARNING Securely support the scooter so that there is no danger of it falling over. 2. Check: 8inner tube Damage/scratches J Replace....

[Page 96] Yamaha 2009 YW125Y

3-43 CHK ADJ CHECKING THE TIRES EAS00163 CHECKING THE TIRES The following procedure applies to both of the tires. 1. Check: 8tire pressure Out of specification J Regulate. WARNING 88 88 8 The tire pressure should only be checked and regulated when th...

[Page 97] Yamaha 2009 YW125Y

3-44 CHK ADJ CHECKING THE TIRES 2. Check: 8tire surfaces Damage/wear J Replace the tire. Minimum tire tread depth 0.8mm (0.03in) 1 Tire tread depth 2 Sidewall 3 Wear indicator WARNING 88 88 8 Do not use a tubeless tire on a wheel designed only for tu...

[Page 98] Yamaha 2009 YW125Y

3-45 CHK ADJ CHECKING THE TIRES Front tire Manufacturer Model Size KENDA K761 120/70-12 51L Rear tire Manufacturer Model Size KENDA K761 130/70-12 56L WARNING New tires have a relatively low grip on the ...

[Page 99] Yamaha 2009 YW125Y

3-46 CHK ADJ EAS00170 CHECKING AND LUBRICATING THE CABLES The following procedure applies to all of the in- ner and outer cables. WARNING Damaged outer cable may cause the cable to corrode and interfere with its movement. Replace damaged outer cable ...

[Page 100] Yamaha 2009 YW125Y

3-47 CHK ADJ LUBRICATING THE LEVERS/LUBRICATING THE SIDESTAND/ LUBRICATING THE CENTERSTAND/LUBRICATING THE REAR SUSPENSION EAS00171 LUBRICATING THE LEVERS Lubricate the pivoting point and metal-to-metal moving parts of the levers. Recommended lubrica...