Yamaha YZ125X1 Owner'S Service Manual Download Page 11

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1-1

DESCRIPTION

GENERAL INFORMATION

DESCRIPTION

• The machine you have purchased may differ slightly from those shown in the following.
• Designs and specifications are subject to change without notice.

Clutch lever

Engine stop switch

Front brake lever

Throttle grip

Radiator cap

Fuel tank cap

Kickstarter crank

Fuel tank

Radiator

10. Coolant drain bolt
11. Check bolt (Transmission oil level)
12. Rear brake pedal
13. Valve joint

14. Fuel cock
15. Air filter
16. Drive chain
17. Shift pedal
18. Starter knob
19. Front fork

Summary of Contents for YZ125X1

Page 1: ...0 SHINGAI IWATA SHIZUOKA JAPAN PRINTED ON RECYCLED PAPER OWNER S SERVICE MANUAL MANUEL D ATELIER DU PROPRIETAIRE FAHRER UND WARTUNGSHANDBUCH MANUALE DI SERVIZIO DEL PROPRIETARIO YZ125 X X1 1C3 28199 3...

Page 2: ...1C3 9 33_cover 07 6 14 9 59 AM Page 2...

Page 3: ...YZ125 X X1 1C3 28199 33 E0 2008 OWNER S SERVICE MANUAL...

Page 4: ......

Page 5: ...S SERVICE MANUAL 2007 by Yamaha Motor Co Ltd 1st Edition June 2007 All rights reserved Any reprinting or unauthorized use without the written permission of Yamaha Motor Co Ltd is expressly prohibited...

Page 6: ...ding 1 THIS MACHINE IS TO BE OP ERATED BY AN EXPERI ENCED RIDER ONLY Do not attempt to operate this machine at maximum power until you are totally familiar with its characteristics 2 THIS MACHINE IS D...

Page 7: ...for the class 500 cc minimum 102 kg 225 lb In modifying your machine e g for weight reduction take note of the above limits of weight HOW TO USE THIS MANUAL FINDING THE REQUIRED PAGE 1 This manual co...

Page 8: ...step by step format sup plements 5 are given in addition to the exploded diagram and job instruction chart ILLUSTRATED SYMBOLS Refer to the illustration Illustrated symbols 1 to 7 are used to identify...

Page 9: ...TABLE OF CONTENTS GENERAL INFORMATION 1 SPECIFICATIONS 2 REGULAR INSPECTION AND ADJUSTMENTS 3 ENGINE 4 CHASSIS 5 ELECTRICAL 6 TUNING 7...

Page 10: ...ND MAINTE NANCE 3 3 ENGINE 3 5 CHASSIS 3 8 ELECTRICAL 3 18 CHAPTER 4 ENGINE SEAT FUEL TANK AND SIDE COVERS 4 1 EXHAUST PIPE AND SI LENCER 4 3 RADIATOR 4 5 CARBURETOR AND REED VALVE 4 7 CYLINDER HEAD C...

Page 11: ...subject to change without notice 1 Clutch lever 2 Engine stop switch 3 Front brake lever 4 Throttle grip 5 Radiator cap 6 Fuel tank cap 7 Kickstarter crank 8 Fuel tank 9 Radiator 10 Coolant drain bol...

Page 12: ...breather hose In this installation make sure the arrow faces the fuel tank and also downward COLLAR tool for YPVS This collar 1 is used to remove and install the push rod of the engine NIPPLE WRENCH...

Page 13: ...rings liberally when installing Do not use compressed air to spin the bearings dry This causes dam age to the bearing surfaces CIRCLIPS 1 All circlips should be inspected carefully before reassembly A...

Page 14: ...tion Crankcase separating tool YU 1135 A 90890 01135 These tool is used to remove the crankshaft from either case Flywheel puller YM 1189 90890 01189 This tool is used to remove the fly wheel magneto...

Page 15: ...ls are used for checking the cooling system Flywheel puller YU 33270 B 90890 01362 These tool is used to split the crank case Steering nut wrench YU 33975 90890 01403 This tool is used when tighten th...

Page 16: ...ch holding tool YM 91042 90890 04086 This tool is used to hold the clutch when removing or installing the clutch boss securing nut Dynamic spark tester YM 34487 Ignition checker 90890 06754 This instr...

Page 17: ...o activate the front brake REAR BRAKE PEDAL The rear brake pedal 1 is located on the right side of the machine Press down on the brake pedal to activate the rear brake FUEL COCK The fuel cock supplies...

Page 18: ...spark plug condi tion it will show a rich condition during break in 5 Allow the engine to cool Restart the engine and operate the ma chine as in the step above for five minutes Then very briefly shift...

Page 19: ...wer bracket Rear For link type Assembly of links Link to frame Link to rear shock absorber Link to swingarm Installation of rear shock absorber Rear shock absorber to frame Installation of swingarm Ti...

Page 20: ...in with a paper towel and lubri cate the chain to prevent rust 7 Clean the seat with a vinyl uphol stery cleaner to keep the cover pliable and glossy 8 Automotive wax may be applied to all painted or...

Page 21: ...stroke 54 54 5 mm 2 126 2 146 in Compression ratio 8 6 10 7 1 Starting system Kick starter Lubrication system Premix 30 1 Yamalube 2 R Oil type or grade 2 stroke Transmission oil Yamalube 4 10W 30 or...

Page 22: ...i Brake Front brake type Single disc brake Operation Right hand operation Rear brake type Single disc brake Operation Right foot operation Suspension Front suspension Telescopic fork Rear suspension S...

Page 23: ...h Plain B 1 0 mm 0 039 in T 2 35 mm 0 093 in End gap installed 0 5 0 7 mm 0 020 0 028 in 1 2 mm 0 047 in Side clearance installed 0 035 0 070 mm 0 0014 0 0028 in 0 1 mm 0 004 in Crankshaft Crank width...

Page 24: ...ade oiled filter Foam air filter oil or equivalent oil Carburetor USA CDN EUROPE AUS NZ ZA Type Manufacturer TMX 38SS MIKUNI I D mark 1C35 30 1C36 40 1C37 50 Main jet M J 410 430 Jet needle clip posit...

Page 25: ...8 mm 1 89 in Front fork top end 5 mm 0 2 in Rear suspension USA CDN ZA AUS NZ EUROPE Shock absorber travel 131 5 mm 5 18 in Spring free length Approx 265 mm 10 43 in Fitting length One I D mark 258 mm...

Page 26: ...mm 0 375 in Caliper cylinder inside dia 22 65 mm 0 892 in 2 Brake fluid type DOT 4 Rear disc brake Disc outside dia Thickness 245 4 0 mm 9 65 0 16 in 245 3 5 mm 9 65 0 14 in Deflection limit 0 15 mm 0...

Page 27: ...tening torque Nm m kg ft lb Spark plug M14S 1 25 1 20 2 0 14 Cylinder head nut M8 1 25 5 28 2 8 20 Cylinder head stud M8 1 25 5 13 1 3 9 4 Cylinder nut M8 1 25 4 30 3 0 22 Cylinder stud M10 1 25 4 13...

Page 28: ...earing plate cover shift cam M6 1 0 2 10 1 0 7 2 Shift guide M6 1 0 2 10 1 0 7 2 Stopper lever M6 1 0 1 10 1 0 7 2 Segment M8 1 25 1 30 3 0 22 Exhaust pipe M6 1 0 2 12 1 2 8 7 Exhaust pipe stay front...

Page 29: ...4 3 Front wheel axle and axle nut M16 1 5 1 105 10 5 75 Front wheel axle holder M8 1 25 4 21 2 1 15 Front brake disc and wheel hub M6 1 0 6 12 1 2 8 7 Rear brake disc and wheel hub M6 1 0 6 14 1 4 10...

Page 30: ...0 8 4 6 0 6 4 3 Cable guide and frame M5 0 8 2 4 0 4 2 9 Fuel tank boss and frame M10 1 25 2 20 2 0 14 Fuel tank M6 1 0 2 10 1 0 7 2 Fuel tank and fuel cock M6 1 0 2 4 0 4 2 9 Fuel tank and seat set...

Page 31: ...s should be at room temperature A Distance between flats B Outside thread diameter DEFINITION OF UNITS A Nut B Bolt TORQUE SPECIFI CATION Nm m kg ft lb 10 mm 6 mm 6 0 6 4 3 12 mm 8 mm 15 1 5 11 14 mm...

Page 32: ...CDI magneto lead 10 YPVS breather hose 11 Engine bracket right 12 Engine bracket left 13 Crankcase breather hose 14 Overflow hose 15 Connector cover A Pass the clutch cable on the out side of the thro...

Page 33: ...eather hose between the frame and connecting rod I Pass the radiator breather hose and YPVS breather hose out side the engine bracket and in side the down tube Then pass the radiator breather hose ins...

Page 34: ...or hose B Using a plastic locking tie clamp the ENGINE STOP button lead ignition coil lead and CDI magneto lead together with the clamp ends backward and then cut off the tie end C Clamp to the frame...

Page 35: ...connector cover into contact with the coupler G Locate the clamp ends in the ar rowed range H Insert the CDI unit band until it stops at the CDI unit stay I Pass the CDI magneto lead and radiator bre...

Page 36: ...on directs as shown and lightly touches the projec tion on the caliper B Pass the brake hose into the brake hose holders C If the brake hose contacts the spring rear shock absorber correct its twist D...

Page 37: ...hose so that its pipe portion directs as shown and lightly touches the projec tion on the master cylinder B Pass the ENGINE STOP but ton lead in the middle of the clutch holder C Clamp the ENGINE STO...

Page 38: ...TON Inspect and clean Inspect crack Replace Inspect carbon deposits and eliminate them PISTON RING Inspect Check ring end gap Replace PISTON PIN SMALL END BEAR ING Inspect Replace CYLINDER HEAD Inspec...

Page 39: ...am air filter oil or equivalent oil Replace FRAME Clean and inspect FUEL TANK COCK Clean and inspect BRAKES Adjust lever position and pedal height Lubricate pivot point Check brake disc surface Check...

Page 40: ...thium base grease THROTTLE CONTROL CABLE Check routing and connection Lubricate Yamaha cable lube or SAE 10W 30 motor oil Item After break in Every race Every third Every fifth As re quired Remarks It...

Page 41: ...d or when the front forks travel up and down Muffler Check that the muffler is tightly mounted and has no cracks P 4 3 4 Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not l...

Page 42: ...ap water 5 Install Copper washer Coolant drain bolt 6 Fill Radiator Engine To specified level Do not mix more than one type of ethylene glycol antifreeze con taining corrosion inhibitors for aluminum...

Page 43: ...de using the adjuster 5 After adjustment check proper op eration of clutch lever 3 Install Cap 1 Boot 2 Place the tip a of the cap in the boot ADJUSTING THE THROTTLE CABLE FREE PLAY 1 Check Throttle g...

Page 44: ...guide with the hole b in air filter element 6 Apply Lithium soap base grease On the matching surface a on air filter element 7 Install Air filter element 1 Washer Fitting bolt Align the projection a o...

Page 45: ...if The system has been disassem bled A brake hose has been loosened or removed The brake fluid is very low The brake operation is faulty A dangerous loss of braking per formance may occur if the brake...

Page 46: ...G THE REAR BRAKE 1 Check Brake pedal height a Out of specification Adjust 2 Adjust Brake pedal height Pedal height adjustment steps a Loosen the locknut 1 b Turn the adjusting nut 2 until the pedal he...

Page 47: ...t 2 Replace Brake pad Brake pad replacement steps a Remove the protector 1 and pad pin plug 2 b Loosen the pad pin 3 c Remove the rear wheel 4 and brake caliper 5 Refer to FRONT WHEEL AND REAR WHEEL s...

Page 48: ...avoid erosion of painted surfaces or plastic parts a Lower level A Front B Rear CHECKING THE SPROCKET 1 Inspect Sprocket teeth a Excessive wear Replace Replace the drive sprocket rear wheel sprocket...

Page 49: ...e axle nut while pushing down the drive chain e Tighten the locknuts CHECKING THE FRONT FORK 1 Inspect Front fork smooth action Operate the front brake and stroke the front fork Unsmooth action oil le...

Page 50: ...uster 2 Be sure to remove all dirt and mud from around the locknut and adjust er before adjustment The length of the spring installed changes 1 5 mm 0 06 in per turn of the adjuster The I D mark b is...

Page 51: ...MPRESSION DAMPING FORCE 1 Adjust High compression damping force By turning the adjuster 1 STANDARD POSITION This is the position which is back by the specific number of turns from the fully turned in...

Page 52: ...G AND ADJUSTING THE STEERING HEAD 1 Elevate the front wheel by placing a suitable stand under the engine 2 Check Steering stem Grasp the bottom of the forks and gently rock the fork assembly back and...

Page 53: ...marks b are in place on both sides Install the handlebar so that the pro jection c of the handlebar upper holder is positioned at the mark on the handlebar as shown Insert the end of the fuel breathe...

Page 54: ...lebar contact 6 Drive chain 7 Throttle roller cable guide 8 Throttle roller sliding surface 9 Tube guide cable winding por tion 10 Throttle cable end 11 Clutch cable end A Use Yamaha cable lube or equ...

Page 55: ...plug Crankcase cover left 2 Attach Dial gauge 1 Spark plug hole dial stand 2 3 Rotate the magneto rotor 1 until the piston reaches top dead cen ter TDC When this happens the needle on the dial gauge w...

Page 56: ...Bolt fuel tank 2 5 Fuel tank 1 6 Left side cover 1 Refer to removal section 7 Right side cover 1 Refer to removal section 8 Number plate 1 Refer to removal section 19 Nm 1 9 m kg 13 ft lb 7 Nm 0 7 m...

Page 57: ...air filter case REMOVING THE NUMBER PLATE 1 Remove Bolt number plate Number plate 1 The projection a is inserted into the band of the number plate Pull the band off the projection before removal Remo...

Page 58: ...section 1 Bolt silencer 2 2 Washer 22 mm 0 87 in 1 2 Washer 26 mm 1 02 in 1 3 Silencer 1 4 Collar L 13 0 mm 0 51 in 1 4 Collar L 15 5 mm 0 61 in 1 5 Collar L 13 5 mm 0 53 in 1 6 Grommet front 1 7 Grom...

Page 59: ...pe Fully apply Quick gasket Yamaha bond No 1215 or equivalent as shown 5 Install Bolt fiber 1 Silencer 2 Bolt silencer front 3 Bolt silencer rear 4 Side cover right A Except for EUROPE B For EUROPE Ya...

Page 60: ...T FUEL TANK AND SIDE COVERS section 1 Radiator guard 2 2 Radiator hose clamp radiator hose 1 3 2 Only loosening 3 Radiator hose 2 1 4 Left radiator 1 5 Radiator hose 4 1 6 Right radiator 1 7 Radiator...

Page 61: ...TOR 1 Install Radiator breather hose 1 Radiator hose 3 2 Radiator hose 1 3 To right radiator 4 Clamp the radiator hose in the direc tion as shown 2 Install Right radiator 1 Washer 2 Bolt right radiato...

Page 62: ...arks Fuel tank Refer to SEAT FUEL TANK AND SIDE COVERS section 1 Clamp carburetor joint 2 Loosen the screw carburetor joint 2 Carburetor 1 3 Carburetor joint 1 4 Reed valve assembly 1 5 Stopper reed v...

Page 63: ...r top 1 Refer to removal section 2 Throttle valve 1 3 Needle holder 1 4 Jet needle 1 5 Float chamber 1 6 Needle jet cover 1 7 Float pin 1 8 Float 1 9 Valve seat 1 10 Main jet 1 11 Main jet holder 1 12...

Page 64: ...CKING THE NEEDLE VALVE 1 Inspect Needle valve 1 Valve seat 2 Grooved wear a Replace Dust b Clean Always replace the needle valve and valve seat as a set CHECKING THE THROTTLE VALVE 1 Check Free moveme...

Page 65: ...eed valve with the reed valve bending as shown Note the cut a in the lower corner of the reed and stopper plate Tighten each screw gradually to avoid warping 2 Install Reed valve assembly 1 Reed valve...

Page 66: ...ber top 1 Screw mixing chamber top 2 To carburetor 3 After installing check the throttle grip for smooth movement 9 Install Air vent hose 1 Overflow hose 2 Clamp 3 Pass the air vent hose at the rear o...

Page 67: ...ND SILENCER section Radiator Refer to RADIATOR section 1 Spark plug 1 2 Engine bracket 2 3 Nut cylinder head 5 Loosen each nut 1 4 turn and remove them after all nuts are loosened 4 Cylinder head 1 5...

Page 68: ...Piston 1 Refer to removal section 4 Small end bearing 1 Refer to removal section 5 Piston ring 1 Refer to removal section 6 Power valve cover 1 7 Thrust plate 1 8 Bolt link lever 1 9 Valve holder 1 1...

Page 69: ...a sharp instrument Avoid scratching the aluminum 2 Inspect Cylinder head water jacket Crust of minerals Rust Re place 3 Measure Cylinder head warpage Out of specification Resurface Warpage measuremen...

Page 70: ...ing rod 5 Check Free play There should be no noticeable free play Free play exists Inspect the connecting rod for wear Replace the pin and or connecting rod as required CHECKING THE PISTON RING 1 Inst...

Page 71: ...nstall Power valve 1 1 Power valve 2 2 Bolt power valve 3 Install the power valve at cut away faced a for down side 2 Install Spring 1 Link lever 2 Collar 3 Valve shaft 4 Valve holder 5 Bolt link leve...

Page 72: ...and connecting rod big end wash ers Install the gasket with the seal print side toward the crankcase 3 Install Piston 1 Piston pin 2 Piston pin clip 3 The arrow a on the piston dome must point to exha...

Page 73: ...ing 1 Apply the lithium soap base grease on the O rings 7 Install Cylinder head 1 Copper washer 2 Nut cylinder head 3 Tighten the nuts cylinder head in stage using a crisscross pattern 8 Install Engin...

Page 74: ...ON OIL section in the CHAPTER 3 Bolt brake pedal Shift the brake pedal downward Rotor and stator Refer to CDI MAGNETO section Clutch cable Disconnect at engine side 1 Clutch cover 1 2 Bolt clutch spri...

Page 75: ...ring 1 5 Ball 1 6 Push rod 2 1 7 Nut clutch boss 1 Refer to removal section 8 Lock washer 1 Refer to removal section 9 Clutch boss 1 Refer to removal section 10 Thrust washer D 34mm 1 34 in 1 11 Prima...

Page 76: ...at all four points CHECKING THE CLUTCH PLATES 1 Measure Clutch plate warpage Out of specification Replace clutch plate as a set Use a surface plate 1 and thick ness gauge 2 CHECKING THE PUSH LEVER SHA...

Page 77: ...r 2 Circlip 3 To push rod 1 4 Apply the lithium soap base grease on the bearing and washer 7 Install Push rod 2 1 Ball 2 Push rod 1 3 Apply the transmission oil on the push rod 1 2 and ball 8 Install...

Page 78: ...he CHAPTER 3 Clutch cable Disconnect at engine side Bolt brake pedal Shift the brake pedal downward Radiator hose 4 Disconnect at water pump side Bolt push rod Refer to CYLINDER HEAD CYLINDER AND PIST...

Page 79: ...SHIFT SHAFT Order Part name Q ty Remarks 1 Kick idle gear 1 2 kick shaft assembly 1 Refer to removal section 3 Shift pedal 1 4 Shift shaft 1 5 Roller 1 6 Shift guide 1 Refer to removal section 7 Shift...

Page 80: ...GEAR CLIP 1 Measure Kick clip friction force Out of specification Replace Use a spring gauge 1 CHECKING THE SHIFT SHAFT 1 Inspect Shift shaft 1 Bend damage Replace Spring 2 Broken Replace CHECKING THE...

Page 81: ...2 Torsion spring 3 To kick shaft 4 Make sure the stopper a of the tor sion spring fits into the hole b on the kick shaft 2 Install Spring guide 1 Slide the spring guide into the kick shaft make sure t...

Page 82: ...r shaft gear 3 with primary drive gear 4 6 Install Bolt crankcase cover right 1 Tighten the bolts in stage using a crisscross pattern 7 Install Kick starter 1 Plain washer 2 Bolt kick starter 3 Instal...

Page 83: ...Right crankcase cover Refer to KICK SHAFT AND SHIFT SHAFT section 1 Governor assembly 1 2 Dowel pin 1 Refer to removal section 3 Retainer 1 4 Ball 4 5 Retainer weight 1 6 Plain washer 4 7 Thrust beari...

Page 84: ...mpression spring 2 Plate 3 Washer 4 Thrust bearing 5 Collar 6 Retainer weight 7 To governor shaft 8 Apply the lithium soap base grease on the thrust bearing 2 Install Ball 1 Retainer 2 To governor sha...

Page 85: ...me Q ty Remarks Crankcase cover right Refer to KICK SHAFT AND SHIFT SHAFT section 1 Water pump housing cover 1 2 Impeller shaft gear 1 3 Dowel pin 1 4 Plain washer 1 5 Impeller shaft assembly 1 6 Bear...

Page 86: ...stall the oil seal with its manufac ture s marks or numbers facing the right crankcase cover 3 2 Install Bearing 1 Install the bearing by pressing its out er race parallel INSTALLING THE IMPELLER SHAF...

Page 87: ...4 32 WATER PUMP...

Page 88: ...Remarks Seat and fuel tank Refer to SEAT FUEL TANK AND SIDE COVERS section Bolt Radiator Refer to RADIATOR section Disconnect the CDI magneto lead 1 Left crankcase cover 1 2 Nut rotor 1 Refer to remo...

Page 89: ...ure that its flat surface a is in parallel with the crankshaft center line b When installing the rotor align the keyway c of the rotor with the woodruff key 3 Install Washer 1 Nut rotor 2 Use the roto...

Page 90: ...to EXHAUST PIPE AND SILENCER section Clutch cable Disconnect at the engine side Radiator Refer to RADIATOR section Spark plug cap Disconnect the CDI magneto lead 1 Drive chain sprocket cover 1 2 Nut d...

Page 91: ...3 10 Pivot shaft 1 Refer to removal section 11 Engine 1 Refer to removal section Order Part name Q ty Remarks 26 Nm 2 6 m kg 19 ft lb 64 Nm 6 4 m kg 46 ft lb 64 Nm 6 4 m kg 46 ft lb 85 Nm 8 5 m kg 61...

Page 92: ...3 Engine mounting bolt front 4 Engine bracket 5 Bolt engine bracket 6 Engine mounting bolt upper 7 Apply the molybdenum disulfide grease on the pivot shaft INSTALLING THE BRAKE PEDAL 1 Install Spring...

Page 93: ...4 38 ENGINE REMOVAL Screw drive chain sprocket cov er 3 Screw drive chain sprocket cover 5 Nm 0 5 m kg 3 6 ft lb...

Page 94: ...Refer to KICK SHAFT AND SHIFT SHAFT section Stopper lever Refer to KICK SHAFT AND SHIFT SHAFT section Rotor and stator Refer to CDI MAGNETO section 1 Segment 1 Refer to removal section 2 Bolt L 45 mm...

Page 95: ...SHAFT 9 Crankshaft 1 Refer to removal section 10 Oil seal 2 11 Bearing 2 Refer to removal section Order Part name Q ty Remarks 30 Nm 3 0 m kg 22 ft lb 10 Nm 1 0 m kg 7 2 ft lb 20 Nm 2 0 m kg 14 ft lb...

Page 96: ...If the cases do not separate check for a remaining case bolt or fitting Do not force REMOVING THE CRANKSHAFT 1 Remove Crankshaft 1 Use the crankcase separating tool 2 Make appropriate bolts 3 as shown...

Page 97: ...CDN B Except for USA and CDN 2 Check Shifter operation Transmission operation Unsmooth operation Repair 3 Apply Sealant On the right crankcase 1 Clean the contacting surface of left and right crankcas...

Page 98: ...with the dowel pin b Turn the segment clockwise until it stops and tighten the bolt If the segment gets an impact it may be damaged Take care not to give an impact to the segment when tightening the b...

Page 99: ...marks Engine Refer to ENGINE REMOVAL section Separate the crankcase Refer to CRANKCASE AND CRANK SHAFT section 1 Guide bar long 1 2 Guide bar short 1 3 Shift cam 1 4 Shift fork 3 1 5 Shift fork 1 1 6...

Page 100: ...k and or guide bar For a malfunctioning shift fork re place not only the shift fork itself but the two gears each adjacent to the shift fork INSTALLING THE TRANSMISSION 1 Install 6th pinion gear 21T 1...

Page 101: ...shift fork 1 L with the 5th wheel gear 4 and 3 R with the 6th wheel gear 6 on the drive axle Mesh the shift fork 2 C with the 3rd 4th pinion gear 5 on the main axle 2 Install Shift cam 1 Apply the tr...

Page 102: ...Order Part name Q ty Remarks Hold the machine by placing the suitable stand under the engine Refer to HANDLING NOTE 1 Bolt axle holder 4 Only loosening 2 Nut front wheel axle 1 3 Front wheel axle 1 4...

Page 103: ...hine by placing the suitable stand under the engine Refer to HANDLING NOTE 1 Nut rear wheel axle 1 2 Rear wheel axle 1 3 Drive chain puller 2 4 Rear wheel 1 Refer to removal section 5 Collar 2 6 Rear...

Page 104: ...flection only rear brake disc Use the dial gauge 1 Out of specification Inspect wheel runout If wheel runout is in good condi tion replace the brake disc 2 Measure Brake disc thickness a Out of limit...

Page 105: ...he lithium soap base grease on the bearing and oil seal lip when installing Install the bearing with seal facing outward Use a socket that matches the out side diameter of the race of the bearing Righ...

Page 106: ...l axle 2 Install the left drive chain puller and insert the wheel axle from left side Apply the lithium soap base grease on the wheel axle 8 Install Right drive chain puller 1 Washer 2 Nut wheel axle...

Page 107: ...and under the engine Refer to HANDLING NOTE Drain the brake fluid Refer to removal section 1 Brake hose holder protector 2 2 Union bolt 2 3 Brake hose 1 4 Pad pin plug 1 Remove when loosening the pad...

Page 108: ...e Refer to HANDLING NOTE Rear wheel Refer to FRONT WHEEL AND REAR WHEEL section Drain the brake fluid Refer to removal section 1 Brake pedal 1 2 Brake master cylinder 1 3 Brake hose holder 2 4 Union b...

Page 109: ...der Part name Q ty Remarks A Front B Rear A B 1 Pad pin 1 1 2 Brake pad 2 2 3 Pad support 1 1 4 Brake caliper piston 2 1 Refer to removal section 5 Brake caliper piston dust seal 2 1 Refer to removal...

Page 110: ...INDER Order Part name Q ty Remarks A Front B Rear 1 Brake master cylinder cap 1 2 Diaphragm 1 3 Reservoir float 1 4 Push rod Front 1 5 Brake master cylinder boot 1 6 Circlip 1 Use a long nose circlip...

Page 111: ...steps a Insert a piece of rag into the brake caliper to lock one brake caliper b Carefully force the piston out of the brake caliper cylinder with compressed air A Front B Rear REMOVING THE BRAKE CAL...

Page 112: ...n Clean them with brake fluid 2 Install Brake caliper piston seal 1 Brake caliper piston dust seal 2 Always use new brake caliper pis ton seals and brake caliper piston dust seals Apply the brake flui...

Page 113: ...tallation cause improper brake performance 3 Install Spring 1 To brake master cylinder piston 2 Install the spring at the smaller dia side 4 Install Brake master cylinder kit 1 Washer front brake 2 Pu...

Page 114: ...otter pin 3 After installing check the brake pedal height Refer to ADJUSTING THE REAR BRAKE section in the CHAP TER 3 INSTALLING THE FRONT BRAKE HOSE 1 Install Copper washer 1 Brake hose 2 Union bolt...

Page 115: ...may result in a harmful chemical reaction and lead to poor performance Be careful that water does not enter the master cylinder when refilling Water will significantly lower the boiling point of the...

Page 116: ...5 15 FRONT BRAKE AND REAR BRAKE A Front B Rear 5 Install rear brake only Protector 1 Bolt protector 2 Bolt protector 7 Nm 0 7 m kg 5 1 ft lb...

Page 117: ...efer to FRONT BRAKE AND REAR BRAKE section Number plate Refer to SEAT FUEL TANK AND SIDE COVERS section in the CHAPTER 4 1 Protector 1 2 Pinch bolt upper bracket 2 Only loosening 3 Damper assembly 1 L...

Page 118: ...Stopper ring 1 Refer to removal section 5 Inner tube 1 Refer to removal section 6 Outer tube 1 7 Piston metal 1 8 Slide metal 1 9 Oil seal washer 1 10 Oil seal 1 11 Base valve 1 Drain the fork oil Ref...

Page 119: ...d the locknut and remove the adjuster Do not remove the locknut as the damper rod may go into the damp er assembly and not be taken out REMOVING THE INNER TUBE 1 Remove Dust seal 1 Stopper ring 2 Usin...

Page 120: ...damage Replace ASSEMBLING THE FRONT FORK 1 Wash the all parts in a clean sol vent 2 Stretch the damper assembly ful ly 3 Fill Front fork oil 1 To damper assembly Be sure to use recommended fork oil I...

Page 121: ...essing fully allow excessive oil to overflow on the base valve side Take care not to damage the damp er assembly 13 Allow the overflowing oil to es cape at the hole a in the damper assembly 14 Check D...

Page 122: ...be is held vertically the damper assembly may fall into it damaging the valve inside 26 Loosen Rebound damping adjuster 1 Loosen the rebound damping ad juster finger tight Record the set position of t...

Page 123: ...ctor guide 1 INSTALLING THE FRONT FORK 1 Install Front fork 1 Temporarily tighten the pinch bolts lower bracket Do not tighten the pinch bolts up per bracket yet 2 Tighten Damper assembly 1 Use the ca...

Page 124: ...ping force Turn in the damping adjuster 1 fin ger tight and then turn out to the orig inally set position 7 Adjust Compression damping force Turn in the damping adjuster 1 fin ger tight and then turn...

Page 125: ...val section 5 Throttle cable cap 1 Turn over the cap cover 6 Throttle cable 1 Disconnect at the throttle side 7 Throttle 1 Loosen the bolts 8 Cap cover 1 9 Collar 1 10 Left grip 1 Refer to removal sec...

Page 126: ...5 25 HANDLEBAR DISASSEMBLING THE THROTTLE Order Part name Q ty Remarks 1 Grip cap lower 1 2 Grip cap upper 1 3 Grip assembly 1 4 Grip right 1 Refer to removal section 5 Tube guide 1...

Page 127: ...p lower 2 Bolt grip cap 3 Temporarily tighten the bolts grip cap INSTALLING THE HANDLEBAR 1 Install Handlebar lower holder 1 Washer 2 Nut handlebar lower holder 3 Install the handlebar lower holder wi...

Page 128: ...ding surface and ca ble guide Install the roller so that the UP PER mark a faces upward Pass the throttle cable in the groove b in the roller 8 Install Throttle cable cap 1 Screw throttle cable cap 2...

Page 129: ...in stalled according to the dimensions shown Pass the engine stop switch lead in the middle of the clutch lever hold er 14 Install Clutch cable 1 Apply the lithium soap base grease on the clutch cabl...

Page 130: ...he suitable stand under the engine Refer to HANDLING NOTE Number plate Refer to SEAT FUEL TANK AND SIDE COVERS section in the CHAPTER 4 Handlebar Refer to HANDLEBAR section Front fender 1 Steering ste...

Page 131: ...5 30 STEERING 9 Bearing race 2 Refer to removal section Order Part name Q ty Remarks...

Page 132: ...ing races Spin the bearings by hand If the bearings hang up or are not smooth in their operation in the bearing races replace bearings and bearing races as a set INSTALLING THE LOWER BRACKET 1 Install...

Page 133: ...If not adjust the steering by loosen ing the steering ring nut little by lit tle 10 Adjust Front fork top end a 11 Tighten Pinch bolt upper bracket 1 Pinch bolt lower bracket 2 Tighten the lower brack...

Page 134: ...NG NOTE Brake hose holder Refer to FRONT BRAKE AND REAR BRAKE section Rear brake caliper Refer to FRONT BRAKE AND REAR BRAKE section Bolt brake pedal Shift the brake pedal backward Drive chain 1 Drive...

Page 135: ...1 Cap 2 Refer to removal section 2 Relay arm 1 3 Connecting rod 1 4 Collar 2 5 Oil seal 2 6 Thrust bearing 2 7 Bushing 2 8 Oil seal 8 9 Bearing 10 Refer to removal section 70 Nm 7 0 m kg 50 ft lb 80...

Page 136: ...seal 3 Damage Replace INSTALLING THE BEARING AND OIL SEAL 1 Install Bearing 1 Oil seal 2 To swingarm Apply the molybdenum disulfide grease on the bearing when install ing Install the bearing by press...

Page 137: ...lybdenum disulfide grease on the bolt circumference and threaded portion Do not tighten the nut yet 6 Install Swingarm 1 Pivot shaft 2 Apply the molybdenum disulfide grease on the pivot shaft Insert t...

Page 138: ...lower chain tensioner 5 14 Install Drive chain support 1 Drive chain support cover 2 Bolt drive chain support L 50 mm 1 97 in 3 Nut drive chain support 4 Bolt drive chain support cover L 10 mm 0 39 i...

Page 139: ...T PIPE AND SILENCER section in the CHAPTER 4 1 Clamp air filter joint 1 Only loosening 2 Rear frame 1 3 Bolt rear shock absorber relay arm 1 Hold the swingarm 4 Bolt rear shock absorber frame 1 5 Rear...

Page 140: ...EAR SHOCK ABSORBER 12 Bearing 2 Refer to removal section Order Part name Q ty Remarks 53 Nm 5 3 m kg 38 ft lb 56 Nm 5 6 m kg 40 ft lb 2 Nm 0 2 m kg 1 4 ft lb 32 Nm 3 2 m kg 23 ft lb 29 Nm 2 9 m kg 21...

Page 141: ...sorber be sure to extract the nitrogen gas from valve 1 Wear eye protec tion to prevent eye damage from es caping gas and or metal chips To dispose of a damaged or worn out rear shock absorber take th...

Page 142: ...isulfide grease on the dust seal lips and col lars Apply the lithium soap base grease on the O rings 2 Install Bushing 1 Collar 2 Dust seal 3 Apply the molybdenum disulfide grease on the bearing and d...

Page 143: ...5 42 REAR SHOCK ABSORBER Bolt rear frame lower 3 7 Tighten Bolt air filter joint 1 Bolt rear frame lower 29 Nm 2 9 m kg 21 ft lb Bolt air filter joint 2 Nm 0 2 m kg 1 4 ft lb...

Page 144: ...AL COMPONENTS 1 Engine stop switch 2 CDI unit 3 Ignition coil 4 CDI magneto 5 Spark plug WIRING DIAGRAM 1 Engine stop switch 2 CDI unit 3 Ignition coil 4 CDI magneto 5 Spark plug COLOR CODE B Black O...

Page 145: ...2 Fuel tank Use the following special tools in this inspection Spark gap test Spark Clean or replace spark plug No spark Check entire ignition system for connection No good Repair or replace OK Check...

Page 146: ...plug cap by turn ing it counterclockwise and inspect Install the spark plug cap by turning it clockwise until it is tight CHECKING THE SPARK PLUG CAP 1 Inspect Spark plug cap Loose connection Tighten...

Page 147: ...electrical components If no fault is found replace the CDI unit Then check the electrical compo nents again Tester lead Black Red lead 1 Tester lead Green White lead 2 Charging coil 1 resis tance Tes...

Page 148: ...ensity Higher humidity reduces the amount of oxygen in the air by so much of the water vapor in the same air Lower atmospheric pressure at a high altitude reduces the density of the air TEST RUN After...

Page 149: ...o 6BFY44 74 has the same effect as a rising of 1 clip position A Difference in straight portion dia B Difference in clip position a Reference needle b 0 5 richer c 1 richer ADJUSTING THE JET NEEDLE Fo...

Page 150: ...7 82 Lean 400 137 80 Pilot jet 2 Size Part number 14142 Rich 50 4KM 50 47 5 4KM 47 STD 45 4KM 45 42 5 4KM 42 STD 40 4KM 40 37 5 4KM 37 35 4KM 35 32 5 4KM 32 Lean 30 4KM 30 Throttle valve 3 Size Part n...

Page 151: ...2 76 4 0 5 richer 6BFY43 72 3 6BFY43 73 3 6BFY43 74 3 6BFY43 75 3 6BFY43 76 3 STD 6BFY42 72 3 6BFY42 73 3 6BFY42 74 3 6BFY42 75 3 6BFY42 76 3 0 5 leaner 6BFY43 72 2 6BFY43 73 2 6BFY43 74 2 6BFY43 75 2...

Page 152: ...mixture Raise jet needle clip position 1 groove up 1 4 3 4 throttle Hard breathing Lack of speed Lower jet needle clip position 1 groove down 1 4 1 2 throttle Slow speed pick up White smoke Poor acce...

Page 153: ...ratio If a course has a long straight por tion where a machine can run at maximum speed the machine is generally set such that it can devel op its maximum revolutions toward the end of the straight l...

Page 154: ...1 The I D mark slits a is proved on the end of the spring REAR SUSPENSION SETTING The rear suspension setting should be made depending on the rider s feeling of an actual run and the circuit conditio...

Page 155: ...ormance Never use one whose overall length is greater than standard REAR SHOCK ABSORBER SETTING PARTS Rear shock spring 1 Equal pitch titanium spring Equal pitch steel spring Unequal pitch steel sprin...

Page 156: ...F AD JUSTMENT b Approx 265 mm 10 43 in One I D mark 245 5 263 5 mm 9 67 10 37 in Two I D marks 251 5 269 5 mm 9 90 10 61 in Three I D marks 243 0 261 0 mm 9 57 10 28 in SPRING FREE LENGTH EXTENT OF AD...

Page 157: ...tire range bottoming out Compression damping Turn adjuster clockwise about 2 clicks to in crease damping Oil amount Increase oil amount by about 5 10 cm3 0 2 0 4 Imp oz 0 2 0 3 US oz Spring Replace wi...

Page 158: ...avy and dragging Rebound damping Turn adjuster counterclockwise about 2 clicks to decrease damping Spring Replace with soft spring Poor road gripping Rebound damping Turn adjuster counterclockwise abo...

Page 159: ......

Page 160: ...PRINTED IN JAPAN E PRINTED ON RECYCLED PAPER YAMAHA MOTOR CO LTD 2500 SHINGAI IWATA SHIZUOKA JAPAN...

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Yamaha YZ125X1, Owner'S Service Manual

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