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 or nut.

EAS00024

BEARINGS AND OIL SEALS Install bearings and oil seals so that the manufacturers 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 appropriate.

1 Oil seal

CAUTION:
Do not spin the bearing with compressed air because this will damage the bearing surfaces.

1 Bearing

EAS00025
CIRCLIPS Before reassembly, check all circlips carefully and replace damaged or distorted circlips. Always replace piston pin clips after one use. When installing a circlip 1, make sure the sharp-edged corner 2 is positioned opposite the thrust 3 that the circlip receives.

4 Shaft

CHECKING THE CONNECTIONS

EAS00026

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. 3. Check: all connections Loose connection Connect properly. NOTE: If the pin 1 on the terminal is flattened, bend it up.
Connect: lead coupler connector
NOTE: Make sure all connections are tight.
5. Check: continuity (with the pocket tester) Pocket tester 90890-03112, YU-03112-C NOTE: If there is no continuity, clean the terminals. When checking the wire harness, perform steps (1) to (3). As a quick remedy, use a contact revitalizer available at most part stores.

SPECIAL TOOLS

EAS00027
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 inappropriate tools or improvised techniques. Special tools, part numbers or both may differ depending on the country. When placing an order, refer to the list provided below to avoid any mistakes. NOTE: For U.S.A. and Canada, use part number starting with YM-, YU-, or ACC-. For others, use part number starting with 90890-. Tool No.
Slide hammer bolt 90890-01083 YU-01083-1 Weight 90890-01084 YU-01083-3

Tool name/Function

Slide hammer bolt Weight

Illustration

These tools are used to remove or install the rocker arm shafts. Crankcase separating tool

90890-01135 YU-01135-B This tool is used to remove the crankshaft. Valve spring compressor 90890-04019 YM-04019 This tool is used to remove or install the valve assemblies. Pot 90890-01274 YU-90058 YU-90059 Bolt 90890-01275 YU-90060 Adapter 90890-01278 YU-90063 Spacer 90890-04081 YM-91044 Crankshaft installer pot Crankshaft installer bolt
These tools are used to install the crankshaft. Adapter (M12) Spacer (crankshaft installer)
These tools are used to install the crankshaft. Piston pin puller set
90890-01304 YU-01304 This tool is used to remove the piston pin.
Tool No. Tool name/Function
Tappet adjusting tool 90890-01311 YM-08035-A This tool is used to adjust the valve clearance. Fuel level gauge 90890-01312 YM-01312-A This gauge is used to measure the fuel level in the float chamber. T-handle 90890-01326 YM-01326
This tool is used to hold the 14 mm hexagon nut/socket wrench when removing or installing the damper rod. Flywheel puller
90890-01362 YU-33270-B This tool is used to remove the generator rotor. Weight 90890-01367 YM-A9409-7 YM-A5142-4 Attachment 90890-01400 Fork seal driver weight Fork seal driver attachment (30) These tools are used to install the oil seal, dust seal, and the outer tube bushing of the front fork legs. Steering nut wrench 90890-01403 YU-33975 This tool is used to loosen or tighten the steering ring nuts. Sheave holder 90890-01701 YS-01880-A
This tool is used to hold the A.C. magneto rotor when loosening or tightening the A.C. magneto rotor nut. Thickness gauge
90890-03079 YM-34483 This tool is used to measure the valve clearance.
Compression gauge 90890-03081 YU-33223 These tools are used to measure the engine compression. Pocket tester 90890-03112 YU-03112-C This tool is used to check the electrical system. Timing light 90890-03141 YU-03141 This tool is used to check the ignition timing. Carburetor angle driver 90890-03158 This tool is used to turn the air screw when adjusting the engine idling speed. Universal clutch holder 90890-04086 YM-91042
This tool is needed to hold the clutch boss when removing or installing the boss nut. Valve guide remover (5)
90890-04097 YM-04097 This tool is needed to remove and install the valve guides. Valve guide installer (5) 90890-04098 YM-04098 This tool is needed to install the valve guides. Valve guide reamer (5) 90890-04099 YM-04099 This tool is needed to rebore the new valve guides.

----------------

CHASSIS SPECIFICATIONS CHASSIS SPECIFICATIONS
Item Frame Frame type Caster angle Trail Front wheel Wheel type Rim Size Material Wheel travel Wheel runout Maximum radial wheel runout Maximum lateral wheel runout Rear wheel Wheel type Rim Size Material Wheel travel Wheel runout Maximum radial wheel runout Maximum lateral wheel runout Front tire Tire type Size Manufacturer/model Tire pressure (cold tire) 0 ~ 90 kg (0 ~ 198 lb) 90 kg ~ Maximum load (198 lb ~ Maximum load) Minimum tire tread depth Standard Diamond 26.33 90.0 mm (3.54 in) Cast wheel J18 1.60 Aluminum 110.0 mm (4.33 in) -------
Limit ---------------------1.0 mm (0.04 in) 0.5 mm (0.02 in) ------------1.0 mm (0.04 in) 0.5 mm (0.02 in) ------------------1.6 mm (0.06 in)
Cast wheel J18 1.85 Aluminum 105.0 mm (4.13 in) -------
With tube 2.75-18 42P CHENG SHIN/SAKURA S-901 PIRELLI/CITY DEMON 175 kPa (1.75 kgf/cm2, 25 psi) 175 kPa (1.75 kgf/cm2, 25 psi) ----

2 - 10

CHASSIS SPECIFICATIONS
Item Rear tire Tire type Size Manufacturer/model Tire pressure (cold tire) 0 ~ 90 kg (0 ~ 198 lb) 90 kg ~ Maximum load (198 lb ~ Maximum load) Minimum tire tread depth Front brake Brake type Operation Front disc brake Diameter thickness Minimum thickness Maximum deflection Brake pad lining thickness-inner Brake pad lining thickness-outer Master cylinder inside diameter Caliper cylinder inside diameter Recommended fluid Rear brake Brake type Operation Brake pedal position Brake pedal free play Rear brake drum Drum brake type Drum inside diameter Lining thickness Shoe spring free length Standard With tube 90/90-18 57P CHENG SHIN/SAKURA S-180 PIRELLI/CITY DEMON 200 kPa (2.00 kgf/cm2, 29 psi) 280 kPa (2.80 kgf/cm2, 41 psi) ----
Limit ------------------1.6 mm (0.06 in) ---------3.5 mm (0.14 in) 0.15 mm (0.0059 in) 0.8 mm (0.03 in) 0.8 mm (0.03 in) ------------------------131.0 mm (5.16 in) 2.0 mm (0.08 in) ----
Single-disc brake Right-hand operation 245.0 4.0 mm (9.65 0.16 in) ------6.0 mm (0.24 in) 6.0 mm (0.24 in) 12.70 mm (0.50 in) 35.03 mm (1.3791 in) DOT 3 or 4 Drum brake Right-foot operation 13.5 mm (0.53 in) 20 ~ 30 mm (0.79 ~ 1.18 in) Leading, trailing 130.0 mm (5.12 in) 4.0 mm (0.16 in) 50.5 mm (1.99 in)

2 - 11

Item Steering Steering bearing type Lock-to-lock angle (left) Lock-to-lock angle (right) No./size of steel balls Upper Lower Front suspension Suspension type Front fork type Front fork travel Spring Free length Installed length Spring rate (K1) Spring rate (K2) Spring stroke (K1) Spring stroke (K2) Optional spring available Fork oil Recommended oil Quantity (each front fork leg) Level (from the top of the inner tube, with the inner tube fully compressed, and without the fork spring) Inner tube outer diameter Inner tube bend limit Rear suspension Suspension type Spring/shock absorber type Rear shock absorber assembly travel Spring Free length Installed length Spring rate (K1) Spring rate (K2) Spring rate (K3) Spring stroke (K1) Spring stroke (K2) Spring stroke (K3) Optional spring available Standard Ball and race bearing 16 pcs 0.250 in 16 pcs 0.250 in Telescopic fork Coil spring/oil damper 120.0 mm (4.72 in) 337.0 mm (13.27 in)

CHAPTER 4 CHASSIS
FRONT WHEEL AND BRAKE DISC... 4-1 FRONT WHEEL...4-2 REMOVING THE FRONT WHEEL.. 4-3 CHECKING THE FRONT WHEEL.. 4-3 CHECKING THE BRAKE DISC...4-5 CHECKING THE SPEEDOMETER GEAR UNIT.. 4-6 INSTALLING THE FRONT WHEEL... 4-6 REAR WHEEL, BRAKE SHOE PLATE, AND REAR WHEEL SPROCKET.... 4-8 REAR WHEEL... 4-8 BRAKE SHOE PLATE AND REAR WHEEL SPROCKET..4-10 REMOVING THE REAR WHEEL.. 4-12 CHECKING THE REAR WHEEL... 4-12 CHECKING THE REAR WHEEL DRIVE HUB.. 4-13 CHECKING AND REPLACING THE REAR WHEEL SPROCKET.4-13 CHECKING THE BRAKE..4-14 ASSEMBLING THE BRAKE SHOE PLATE..4-15 INSTALLING THE REAR WHEEL AND REAR WHEEL SPROCKET. 4-16 FRONT BRAKE... 4-18 FRONT BRAKE PADS...4-18 REPLACING THE FRONT BRAKE PADS... 4-19 FRONT BRAKE MASTER CYLINDER..4-22 DISASSEMBLING THE FRONT BRAKE MASTER CYLINDER. 4-25 CHECKING THE FRONT BRAKE MASTER CYLINDER. 4-25 ASSEMBLING AND INSTALLING THE FRONT BRAKE MASTER CYLINDER... 4-26 FRONT BRAKE CALIPER... 4-29 DISASSEMBLING THE FRONT BRAKE CALIPER..4-31 CHECKING THE FRONT BRAKE CALIPER..4-32 ASSEMBLING AND INSTALLING THE FRONT BRAKE CALIPER. 4-33 FRONT FORK...4-36 REMOVING THE FRONT FORK LEGS.. 4-40 DISASSEMBLING THE FRONT FORK LEGS.. 4-40 CHECKING THE FRONT FORK LEGS.. 4-41 ASSEMBLING THE FRONT FORK LEGS... 4-42 INSTALLING THE FRONT FORK LEGS.. 4-45 HANDLEBAR...4-46 REMOVING THE HANDLEBAR..4-48 CHECKING THE HANDLEBAR..4-48 INSTALLING THE HANDLEBAR.. 4-48
STEERING HEAD... 4-52 HEADLIGHT AND METER ASSEMBLY.. 4-52 LOWER BRACKET... 4-54 REMOVING THE LOWER BRACKET...4-56 CHECKING THE STEERING HEAD..4-56 INSTALLING THE STEERING HEAD...4-57 DRIVE CHAIN AND DRIVE SPROCKET..4-59 REMOVING THE DRIVE CHAIN... 4-61 CHECKING THE DRIVE CHAIN... 4-61 INSTALLING THE DRIVE CHAIN... 4-63 REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM. 4-65 REMOVING THE REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM...4-67 CHECKING THE REAR SHOCK ABSORBER ASSEMBLIES. 4-68 CHECKING THE SWINGARM...4-68 INSTALLING THE REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM...4-70
FRONT WHEEL AND BRAKE DISC

EAS00512

CHASSIS
Job/Part Removing the front wheel and brake disc
Remarks Remove the parts in the order listed. NOTE: Place the vehicle on a suitable stand so that the front wheel is elevated.
Speedometer cable Brake caliper Wheel axle Front wheel Speedometer gear unit Spacer Dust cover Brake disc
Refer to REMOVING THE FRONT WHEEL and INSTALLING THE FRONT WHEEL.
For installation, reverse the removal procedure.

4 - 14

4. Measure: brake drum inside diameter a Out of specification Replace the wheel. Brake drum inside diameter limit (maximum) 131.0 mm (5.16 in) 5. Check: brake camshaft Damage/wear Replace.

EAS00570

ASSEMBLING THE BRAKE SHOE PLATE 1. Lubricate: brake camshaft brake shoe plate Recommended lubricant Lithium-soap-based grease 2. Install: brake camshaft 1 brake shoe wear indicator 2 brake camshaft lever
10 Nm (1.0 m kg, 7.2 ft lb)
a. Install the brake camshaft so its punch mark a is positioned as shown. b. Align the projection b on the brake shoe wear indicator with the notch in the brake camshaft. c. Align the slot c in the brake camshaft lever with the notch in the brake camshaft. d. Check that the brake shoes are properly positioned.
WARNING After installing the brake camshaft, remove any excess grease. 3. Install: brake shoe springs 1 brake shoes NOTE: Do not to damage the springs during installation. Install the brake shoe springs as shown.

4 - 15

EAS00573
INSTALLING THE REAR WHEEL AND REAR WHEEL SPROCKET 1. Lubricate: O-ring oil seals Recommended lubricant YAMAHA GREASE F 150G

2 New 1

Install: rear wheel sprocket 1 lock washers 2 New rear wheel sprocket bolts
40 Nm (4.0 m kg, 29 ft lb)
3. Bend the lock washer tabs along a flat side of each bolt.
4. Install: chain pullers (left and right) 1 NOTE: Install each chain puller with its alignment mark a facing outward. 5. Adjust: drive chain slack Drive chain slack 20 ~ 30 mm (0.79 ~ 1.18 in) Refer to ADJUSTING THE DRIVE CHAIN SLACK in chapter 3. 6. Tighten: wheel axle nut
91 Nm (9.1 m kg, 66 ft lb)

4 - 16

7. Install: brake torque rod
19 Nm (1.9 m kg, 13 ft lb)
8. Adjust: brake pedal free play Refer to ADJUSTING THE REAR BRAKE in chapter 3.

4 - 17

FRONT BRAKE

EAS00576

FRONT BRAKE PADS
23 Nm (2.3 m kg, 17 ft Ib)

Order 5 6

Job/Part Removing the front brake pads Brake hose holder Brake caliper bolt Brake caliper Brake pad Brake pad shim Brake pad spring

Qty 1 2

Refer to REPLACING THE FRONT BRAKE PADS.

4 - 18

EAS00579
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. Never use solvents on internal brake components. Use only clean or new brake fluid for cleaning brake components. Brake fluid may damage painted surfaces and plastic parts. Therefore, always clean up any spilt brake fluid immediately. Avoid brake fluid coming into contact with the eyes as it can cause serious injury. FIRST AID FOR BRAKE FLUID ENTERING THE EYES: Flush with water for 15 minutes and get immediate medical attention.

Disconnect.

Refer to INSTALLING THE HANDLEBAR.
Refer to REMOVING THE HANDLEBAR. Refer to INSTALLING THE HANDLEBAR.
Disconnect. Refer to REMOVING THE HANDLEBAR.

4 - 46

Order 16 17
Job/Part Left handlebar switch Handlebar grip Clutch lever Clutch lever holder Handlebar holder Handlebar
Qty Remarks 1 Refer to INSTALLING THE HANDLEBAR. 1 Refer to REMOVING THE HANDLEBAR. Refer to INSTALLING THE HANDLE2 BAR. 1 For installation, reverse the removal procedure.

4 - 47

EAS00666
REMOVING THE HANDLEBAR 1. Stand the vehicle on a level surface. WARNING
Securely support the vehicle so that there is no danger of it falling over.
2. Remove: front brake light switch clutch switch NOTE: Push the fastener to remove the front brake light switch from the brake master cylinder. Push the fastener to remove the clutch switch from the clutch lever holder.
3. Remove: handlebar grip 1 NOTE: Blow compressed air between the handlebar and the handlebar grip, and gradually push the grip off the handlebar.

EAS00668

CHECKING THE HANDLEBAR 1. Check: handlebar Bends/cracks/damage Replace. WARNING
Do not attempt to straighten a bent handlebar as this may dangerously weaken it.

EAS00670

INSTALLING THE HANDLEBAR 1. Stand the vehicle on a level surface. WARNING

4 - 48

2. Install: handlebar 1 handlebar holders 2
First, tighten the bolts on the front side of the handlebar holder, and then on the rear side. Turn the handlebar all the way to the left and right. If there is any contact with the fuel tank, adjust the handlebar position. NOTE: The handlebar holders should be installed with the match marks a facing forward. Align the match mark b on the handlebar with the upper surface of the lower bracket.
3. Install: clutch lever holder 1 NOTE: Align the slit of the clutch lever holder with the match mark a on the handlebar.
4. Install: handlebar grip 1 grip end 2
a. Apply a thin coat of rubber adhesive onto the left end of the handlebar and grip end. b. Slide the handlebar grip over the left end of the handlebar. c. Wipe off any excess rubber adhesive with a clean rag. WARNING
Do not touch the handlebar grip until the rubber adhesive has fully dried. NOTE: There should be 1 ~ 2 mm (0.04 ~ 0.08 in) of clearance a between the handlebar grip and the grip end.

4 - 49

Refer to INSTALLING THE STEERING HEAD.

4 - 54

Order 13 14
Job/Part Lower bearing outer race Lower bearing inner race
Remarks Refer to INSTALLING THE STEERING HEAD. For installation, reverse the removal procedure.

4 - 55

EAS00677
REMOVING THE LOWER BRACKET 1. Stand the vehicle on a level surface. WARNING
Securely support the vehicle so that there is no danger of it falling over. 2. Remove: upper ring nut 1 rubber washer lower ring nut 2 (with the steering nut wrench 3) Steering nut wrench 90890-01403, YU-33975 WARNING
Securely support the lower bracket so that there is no danger of it falling.

EAS00681

CHECKING THE STEERING HEAD 1. Wash: bearings bearing races Recommended cleaning solvent Kerosene 2. Check: bearings bearing races Damage/pitting Replace.

4 - 56

3. Replace: bearings bearing races
a. Remove the bearing races from the steering head pipe with a long rod 1 and hammer. b. Remove the bearing race from the lower bracket with a floor chisel 2 and hammer. c. Install new bearing races. CAUTION:
If the bearing race is not installed properly, the steering head pipe could be damaged. NOTE: Always replace the bearings and bearing races as a set.
4. Check: upper bracket lower bracket (along with the steering stem) Bends/cracks/damage Replace.

EAS00683

INSTALLING THE STEERING HEAD 1. Lubricate: upper bearing lower bearing bearing races Recommended lubricant Lithium-soap-based grease
Install: lower ring nut 1 rubber washer 2 upper ring nut 3 lock washer 4 Refer to CHECKING AND ADJUSTING THE STEERING HEAD in chapter 3.

4 - 57

3. Install: upper bracket steering stem nut
NOTE: Temporarily tighten the steering stem nut.
4. Install: front fork legs Refer to INSTALLING THE FRONT FORK LEGS. NOTE: Temporarily tighten the upper and lower bracket pinch bolts.
5. Tighten: steering stem nut
110 Nm (11.0 m kg, 80 ft lb)
6. Adjust: headlight beam (vertically) Refer to ADJUSTING THE HEADLIGHT BEAM in chapter 3.

4 - 58

DRIVE CHAIN AND DRIVE SPROCKET

EAS00700

Job/Part Removing the drive chain and drive sprocket Rear wheel
Remarks Remove the parts in the order listed. Refer to REAR WHEEL, BRAKE SHOE PLATE, AND REAR WHEEL SPROCKET. Refer to REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM.
Drive chain cover Drive sprocket cover Master link clip Master link plate O-ring Master link body Drive chain 1 1
Refer to INSTALLING THE DRIVE CHAIN.

4 - 59

Order 7 8
Job/Part Drive sprocket holder Drive sprocket
Remarks Refer to REMOVING THE DRIVE CHAIN and INSTALLING THE DRIVE CHAIN. For installation, reverse the removal procedure.

59 Nm (5.9 m kg, 43 ft lb) 26 Nm (2.6 m kg, 19 ft lb)
footrest bracket lower bolts 4. Install: rear shock absorber assembly upper nuts
40 Nm (4.0 m kg, 29 ft lb) 32 Nm (3.2 m kg, 23 ft lb)
rear shock absorber assembly lower nuts 5. Adjust: drive chain slack Refer to ADJUSTING THE DRIVE CHAIN SLACK in chapter 3. Drive chain slack 20 ~ 30 mm (0.79 ~ 1.18 in)

4 - 70

CHAPTER 5 ENGINE
ENGINE REMOVAL...5-1 MUFFLER ASSEMBLY....5-1 CABLES, LEADS, HOSES AND FOOTREST..5-2 ENGINE.... 5-5 INSTALLING THE ENGINE... 5-6 CYLINDER HEAD.... 5-7 REMOVING THE CYLINDER HEAD..5-9 CHECKING THE CYLINDER HEAD..5-10 CHECKING THE TAPPET COVERS AND CAMSHAFT SPROCKET COVER.... 5-11 CHECKING THE TIMING CHAIN TENSIONER.. 5-11 CHECKING THE CAMSHAFT SPROCKET..5-12 INSTALLING THE CYLINDER HEAD...5-12 ROCKER ARMS AND CAMSHAFT..5-16 REMOVING THE ROCKER ARMS AND CAMSHAFT.. 5-17 CHECKING THE CAMSHAFT...5-17 CHECKING THE ROCKER ARMS AND ROCKER ARM SHAFTS. 5-18 INSTALLING THE ROCKER ARMS AND CAMSHAFT. 5-19 VALVES AND VALVE SPRINGS... 5-21 REMOVING THE VALVES... 5-22 CHECKING THE VALVES AND VALVE GUIDES..5-23 CHECKING THE VALVE SEATS.. 5-25 CHECKING THE VALVE SPRINGS... 5-27 INSTALLING THE VALVES... 5-27 CYLINDER AND PISTON... 5-29 REMOVING THE CYLINDER AND PISTON..5-30 CHECKING THE CYLINDER AND PISTON..5-30 CHECKING THE PISTON RINGS... 5-32 CHECKING THE PISTON PIN...5-33 INSTALLING THE PISTON AND CYLINDER...5-33
CLUTCH....5-35 CLUTCH COVER...5-35 CLUTCH... 5-37 CLUTCH PUSH LEVER...5-39 REMOVING THE CLUTCH... 5-40 CHECKING THE FRICTION PLATES...5-40 CHECKING THE CLUTCH PLATES..5-41 CHECKING THE CLUTCH SPRINGS...5-41 CHECKING THE CLUTCH HOUSING..5-42 CHECKING THE CLUTCH BOSS... 5-42 CHECKING THE PRESSURE PLATE..5-42 CHECKING THE CLUTCH PUSH LEVER AND SHORT CLUTCH PUSH ROD... 5-42 CHECKING THE PRIMARY DRIVE GEAR AND PRIMARY DRIVEN GEAR.... 5-43 INSTALLING THE CLUTCH... 5-43 SHIFT SHAFT AND STOPPER LEVER... 5-47 CHECKING THE SHIFT SHAFT... 5-48 CHECKING THE STOPPER LEVER..5-48 CHECKING THE SHIFT DRUM SEGMENT..5-48 INSTALLING THE SHIFT SHAFT AND SHIFT PEDAL. 5-48 KICKSTARTER... 5-50 CHECKING THE KICKSTARTER... 5-52 INSTALLING THE KICKSTARTER.. 5-52 STARTER CLUTCH AND A.C. MAGNETO ROTOR. 5-53 REMOVING THE A.C. MAGNETO ROTOR..5-56 REMOVING THE STARTER CLUTCH...5-57 CHECKING THE PICKUP COIL/STATOR ASSEMBLY. 5-57 CHECKING THE STARTER CLUTCH..5-57 INSTALLING THE STARTER CLUTCH.. 5-58 INSTALLING THE A.C. MAGNETO ROTOR..5-59 OIL PUMP.... 5-61 CHECKING THE OIL PUMP.. 5-63 CHECKING THE OIL STRAINER... 5-63 CHECKING THE ROTARY FILTER... 5-64 ASSEMBLING THE OIL PUMP...5-64 INSTALLING THE OIL PUMP...5-65 INSTALLING THE ROTARY FILTER..5-65 CRANKCASE...5-66 CRANKCASE BEARINGS... 5-68 SEPARATING THE CRANKCASE... 5-69 CHECKING THE CRANKCASE..5-69 CHECKING THE TIMING CHAIN AND TIMING CHAIN GUIDE. 5-70 CHECKING THE BEARINGS AND OIL SEALS.. 5-70 ASSEMBLING THE CRANKCASE... 5-70

55 Nm (5.5 m kg, 40 ft Ib)
Job/Part Removing the engine
Remarks Remove the parts in the order listed. NOTE: Place a suitable stand under the engine.
Lower engine bracket bolt/nut Front mounting bolt/nut Lower engine bracket Upper mounting bolt/nut Upper engine bracket bolt/nut Right upper engine bracket Left upper engine bracket Rear mounting bolt/nut Engine

2/2 2/1/1 2/1 1/1 1

Refer to INSTALLING THE ENGINE.

EAS00192

INSTALLING THE ENGINE 1. Install: rear mounting bolt/nut 1 left upper engine bracket 2 right upper engine bracket 3 upper engine bracket bolts/nuts 4 upper mounting bolt/nut 5 lower engine bracket 6 front mounting bolts/nuts 7 lower engine bracket bolts/nuts 8 NOTE: Do not fully tighten the bolts.
2. Tighten: rear mounting bolt/nut 1
38 Nm (3.8 m kg, 27 ft lb) 38 Nm (3.8 m kg, 27 ft lb) 38 Nm (3.8 m kg, 27 ft lb) 38 Nm (3.8 m kg, 27 ft lb) 55 Nm (5.5 m kg, 40 ft lb)
upper engine bracket bolts/nuts 4 upper mounting bolt/nut 5 front mounting bolts/nuts 7 lower engine bracket bolts/nuts 8

T. T. T. T.

R. R. R. R. R.

CYLINDER HEAD

EAS00221
Yamaha bond No.1215 90890-85505 Order Job/Part Qty Remarks Removing the cylinder head Remove the parts in the order listed. Side cover (left and right)/seat/fuel tank Refer to SIDE COVERS, SEAT AND FUEL TANK in chapter 3. Muffler assembly Refer to ENGINE. Refer to STARTER CLUTCH AND A.C. Timing mark accessing screw/crankshaft end accessing screw MAGNETO ROTOR. Carburetor assembly Refer to CARBURETOR in chapter 6. Air induction system pipe/air induction Refer to AIR INDUCTION SYSTEM in system vacuum hose chapter 6. Upper engine bracket (left and right) 2 Spark plug cap 1 Disconnect. Spark plug 1 Camshaft sprocket cover 1 Intake tappet cover 1
Yamaha bond No.1215 90890-85505 Order 14 Job/Part Exhaust tappet cover Intake manifold Timing chain tensioner cap bolt Timing chain tensioner Timing chain tensioner gasket Camshaft sprocket Cylinder head Cylinder head gasket Dowel pin Qty 2 Remarks
Refer to REMOVING THE CYLINDER HEAD and INSTALLING THE CYLINDER HEAD.

EAS00225

REMOVING THE CYLINDER HEAD 1. Align: I mark a on the A.C. magneto rotor (with the stationary pointer b on the A.C. magneto rotor cover)

a 4.8 mm (0.19 in) from the bottom edge of the piston
Piston size P 53.997 ~ 54.029 mm (2.1259 ~ 2.1271 in) d. If out of specification, replace the piston and piston rings as a set. e. Calculate the piston-to-cylinder clearance with the following formula. Piston-to-cylinder clearance = Cylinder bore C Piston skirt diameter P Piston-to-cylinder clearance 0.019 ~ 0.035 mm (0.0007 ~ 0.0014 in) <Limit>: 0.15 mm (0.0059 in) f. If out of specification, replace the cylinder, and the piston and piston rings as a set.

5 - 31

EAS00263
CHECKING THE PISTON RINGS 1. Measure: piston ring side clearance Out of specification Replace the piston and piston rings as a set. NOTE: Before measuring the piston ring side clearance, eliminate any carbon deposits from the piston ring grooves and piston rings.
Piston ring side clearance Top ring 0.035 ~ 0.070 mm (0.0014 ~ 0.0028 in) <Limit>: 0.120 mm (0.0047 in) 2nd ring 0.020 ~ 0.060 mm (0.0008 ~ 0.0024 in) <Limit>: 0.120 mm (0.0047 in) 2. Install: piston rings (into the cylinder) NOTE: Level the piston rings into the cylinder with the piston crown.
a 15 ~ 20 mm (0.59 ~ 0.79 in)
3. Measure: piston ring end gap Out of specification Replace the piston ring. NOTE: The oil ring expander spacers end gap cannot be measured. If the oil ring rails gap is excessive, replace all three piston rings.
Piston ring end gap Top ring 0.15 ~ 0.30 mm (0.006 ~ 0.012 in) <Limit>: 0.55 mm (0.022 in) 2nd ring 0.30 ~ 0.45 mm (0.012 ~ 0.018 in) <Limit>: 0.80 mm (0.031 in) Oil ring 0.20 ~ 0.70 mm (0.008 ~ 0.028 in)

5 - 32

EAS00265
CHECKING THE PISTON PIN 1. Check: piston pin Blue discoloration/grooves Replace the piston pin and then check the lubrication system. 2. Measure: piston pin outside diameter a Out of specification Replace the piston pin. Piston pin outside diameter 14.991 ~ 15.000 mm (0.5902 ~ 0.5906 in) <Limit>: 14.971 mm (0.5894 in) 3. Measure: piston pin bore inside diameter b Out of specification Replace the piston. Piston pin bore inside diameter 15.002 ~ 15.013 mm (0.5906 ~ 0.5911 in) <Limit>: 15.043 mm (0.5922 in) 4. Calculate: piston-pin-to-piston-pin-bore clearance Out of specification Replace the piston pin and piston as a set. Piston-pin-to-piston-pin-bore clearance = Piston pin bore diameter b Piston pin outside diameter a Piston-pin-to-piston clearance 0.002 ~ 0.022 mm (0.0001 ~ 0.0009 in) <Limit>: 0.072 mm (0.0028 in)

EAS00368

CHECKING THE OIL STRAINER 1. Check: oil strainer Damage Replace. Contaminants Clean with solvent.

5 - 63

EAS00371
CHECKING THE ROTARY FILTER 1. Check: rotary filter Cracks/damage/wear Replace. Contaminants Clean with engine oil.

EAS00375

ASSEMBLING THE OIL PUMP 1. Lubricate: inner rotor outer rotor oil pump shaft (with the recommended lubricant) Recommended lubricant Engine oil 2. Install: inner rotor 1 dowel pin 2 oil pump housing cover
5 Nm (0.5 m kg, 3.6 ft lb)
NOTE: When installing the inner rotor, align the pin in the oil pump shaft with the groove a in the inner rotor.
Install: dowel pin 1 oil pump driven gear 2 spring washer 3 washer circlip New
NOTE: When installing the oil pump driven gear, align the pin in the oil pump shaft with groove a in the oil pump driven gear. Install the spring washer as shown in the illustration. 4. Check: oil pump operation Refer to CHECKING THE OIL PUMP.

5 - 64

EAS00376
INSTALLING THE OIL PUMP 1. Install: oil pump gasket 1 New oil pump 7 Nm (0.7 m kg, 5.1 ft lb)
CAUTION: After tightening the bolts, make sure the oil pump turns smoothly. NOTE: Install the oil pump gasket as shown in the illustration.

EAS00377

INSTALLING THE ROTARY FILTER 1. Install: rotary filter 1
NOTE: Align the projection a on the rotary filter with the oil hole b in the crankshaft.

5 - 65

CRANKCASE CRANKCASE
10 Nm (1.0 m kg, 7.2 ft Ib) 4 Nm (0.4 m kg, 2.9 ft Ib)
Job/Part Separating the crankcase Engine Cylinder head Cylinder/piston A.C. magneto rotor/starter clutch idle gear Clutch/primary drive gear Kickstarter assembly/kickstarter idle gear Oil pump Shift shaft/shift drum segment Timing chain guide (intake side) Timing chain Neutral switch
Remarks Remove the parts in the order listed. Refer to ENGINE REMOVAL. Refer to CYLINDER HEAD. Refer to CYLINDER AND PISTON. Refer to STARTER CLUTCH AND A.C. MAGNETO ROTOR. Refer to CLUTCH. Refer to KICKSTARTER. Refer to OIL PUMP. Refer to SHIFT SHAFT AND STOPPER LEVER.

5 - 66

CRANKCASE

Order 6 7

Job/Part Clutch cable holder Right crankcase Left crankcase Dowel pin
Remarks Refer to SEPARATING THE CRANKCASE.

5 - 67

CRANKCASE BEARINGS
Job/Part Removing the crankcase bearings Crankshaft/balancer shaft Transmission Oil seal Bearing retainer Bearing
Remarks Remove the parts in the order listed. Refer to CRANKSHAFT. Refer to TRANSMISSION.
7 For installation, reverse the removal procedure.

EAS00425

CHECKING THE TRANSMISSION 1. Measure: main axle runout (with a centering device and dial gauge 1) Out of specification Replace the main axle. Main axle runout limit 0.03 mm (0.0012 in)

5 - 80

2. Measure: drive axle runout (with a centering device and dial gauge 1) Out of specification Replace the drive axle. Drive axle runout limit 0.03 mm (0.0012 in)
3. Check: transmission gears Blue discoloration/pitting/wear Replace the defective gear(s). transmission gear dogs Cracks/damage/rounded edges Replace the defective gear(s). 4. Check: transmission gear engagement (each pinion gear to its respective wheel gear) Incorrect Reassemble the transmission axle assemblies. 5. Check: transmission gear movement Rough movement Replace the defective part(s). 6. Check: circlips Bends/damage/looseness Replace.

EAS00288

CHECKING THE LONG CLUTCH PUSH ROD 1. Check: long clutch push rod Cracks/damage/wear Replace the long clutch push rod. 2. Measure: long clutch push rod bending limit Out of specification Replace the long clutch push rod. Long clutch push rod bending limit 0.500 mm (0.0197 in)

5 - 81

EBS00355
ASSEMBLING THE MAIN AXLE AND DRIVE AXLE 1. Install: washer 1 circlip 2 New NOTE: Be sure the circlip sharp-edged corner a is positioned opposite side to the toothed washer and gear. Be sure the circlip end b is positioned at axle spline groove c.
2. Install: 5th pinion gear 1 NOTE: Press the 5th pinion gear into the main axle 2, as shown in the illustration.
a 83.25 ~ 83.45 mm (3.278 ~ 3.285 in)

EAS00430

INSTALLING THE TRANSMISSION 1. Install: washer drive axle assembly long clutch push rod main axle assembly shift fork C 1 shift fork L 2 shift fork R 3 short shift fork guide bar 4 long shift fork guide bar 5 NOTE: The embossed marks on the shift forks should face towards the right side of the engine and be in the following sequence: R, C, and L. Make sure that the shift fork cam follower is properly seated in the shift drum groove.

5 - 82

2. Check: transmission Rough movement Repair. NOTE: Apply engine oil to each gear, shaft, and bearing thoroughly. Before assembling the crankcase, make sure that the transmission is in neutral and that the gears turn freely.

5 - 83

CHAPTER 6 CARBURETOR
CARBURETOR...6-1 CHECKING THE CARBURETOR... 6-4 ASSEMBLING THE CARBURETOR..6-5 INSTALLING THE CARBURETOR... 6-7 MEASURING AND ADJUSTING THE FUEL LEVEL..6-7 CHECKING THE FUEL COCK...6-8 AIR INDUCTION SYSTEM...6-9 AIR INJECTION.... 6-9 AIR CUT-OFF VALVE... 6-9 AIR INDUCTION SYSTEM DIAGRAMS.. 6-10 AIR CUT-OFF VALVE ASSEMBLY.. 6-11 CHECKING THE AIR INDUCTION SYSTEM..6-12

4. Dimmer switch Check the dimmer switch for continuity. Refer to CHECKING THE SWITCHES. Is the dimmer switch OK? YES NO The dimmer switch is faulty. Replace the left handlebar switch.

EAS00748

5. Pickup coil resistance Disconnect the pickup coil coupler from the wire harness. Connect the pocket tester ( 100) to the pickup coil coupler as shown. Positive tester probe white 1 Negative tester probe red 2
Does the headlight relay have continuity between brown and blue/black? YES NO Replace the headlight relay.

7 - 27

EAS00787 EAS00788
7. Wiring Check the entire lighting systems wiring. Refer to CIRCUIT DIAGRAM. Is the lighting systems wiring properly connected and without defects? YES Check the condition of each of the lighting systems circuits. Refer to CHECKING THE LIGHTING SYSTEM. NO Properly connect or repair the lighting systems wiring.
CHECKING THE LIGHTING SYSTEM 1. The headlight and the high beam indicator light fail to come on. 1. Headlight bulb and socket Check the headlight bulb and socket for continuity. Refer to CHECKING THE BULBS AND BULB SOCKETS. Are the headlight bulb and socket OK? YES NO Replace the headlight bulb, socket or both. 2. High beam indicator light bulb and socket Check the high beam indicator light bulb and socket for continuity. Refer to CHECKING THE BULBS AND BULB SOCKETS. Is the high beam indicator light bulb and socket OK? YES NO Replace the high beam indicator light bulb, socket or both.

7 - 28

3. Voltage Connect the pocket tester (DC 20 V) to the headlight coupler (wire harness side), meter assembly coupler (wire harness side), and high beam indicator light connector (left handlebar switch side) as shown.
When the dimmer switch is set to When the dimmer switch is set to
Set the main switch to ON. Start the engine. Set the dimmer switch to or . Measure the voltage (DC 12 V) of yellow 1 (green 2) on the headlight coupler (wire harness side) and yellow 4 on the high beam indicator light connector (left handlebar switch side). Is the voltage within specification? YES NO The wiring circuit is faulty and must be repaired.

For Immediate Release:

New Yamaha 125 Haynes Manual
Introduced in 2005 to fill the 125cc gap in its line-up (the longrunning SR125 having been discontinued in 2003), Yamaha's YBR125 road bike was economical, uncomplicated and reliable. MCN said about it: Not the most stylish kid on the block but, as budget, basic learners go, the Yamaha YBR125 offers pretty good value for money. The same publication gave it four out of five stars for value, a rating matched by owners of the zippy little machines. Yamaha eschewed the high-tech route chosen by other motorcycle makers for their 125cc models and chose a four-stroke, air-cooled engine with a Mikuni carburettor. Styling was understated too, except for the two sister XT models built in Italy rather than Japan where the road bike is manufactured. The XT125R had 'enduro' styling similar to the larger engined XT660R while the XT125X had 'supermotard' styling, with 17-inch wheels, smooth tyres and sharper steering geometry. In 2008 there was the YBR125 Custom with revised styling and lots of chrome, which used the fuel injected engine now fitted to the standard YBR model. Again to quote MCN: Things rarely go wrong with Yamaha YBR125s but, if they do, parts are inexpensive and easy to find plus the Yamaha YBR125 is simple to work on yourself, saving even more money. The 14.99 price of the new Haynes Manual for the Yamaha 125 will soon be recovered from savings on straightforward DIY maintenance tasks such as brake pad swaps, oil changes and spark plug replacement. Indeed, this new Haynes Service and Repair Manual will help you get the most from your Yamaha in several ways. The Manual provides information on routine maintenance and servicing and advises on diagnosis and rectification when random faults occur. It will help you decide what work needs be done whether by yourself or by a dealer. You may do simpler jobs more quickly than booking the motorcycle into a dealer. Perhaps most importantly, using this Haynes Manual to do work yourself saves money by avoiding the costs a dealer must charge to cover its labour and overheads. The manual has illustrations and descriptions to show the function of the various components so that their layout can be understood. Tasks are described and photographed in a clear stepby-step sequence with details of any special tools required and a complexity rating given. There are sections on pre-ride checks and routine maintenance and instructions for straightforward tasks such as checking fluid levels and filter changes, plus repair information such as clutch plate renewal and engine overhaul. Step-by-step procedures with hundreds of illustrations and photographs. Written from hands-on experience using commonly available tools. Haynes Hints provide invaluable short cuts and professional know-how. Tool Tips save time and money and reduce frustration. 'Spanner ratings' indicate how difficult each job is. Quick and easy fault diagnosis, maintenance and servicing sections.
Models covered by this manual: YBR125ED 2005 to 2009, YBR125 Custom 2008 and 2009, XT125R 2005 to 2009, XT125X 2005 to 2009 This Haynes Manual retails at 14.99 (softback) and is available from www.haynes.co.uk or from all good bike dealers and Halfords. For further information, or to request a review copy, please contact Eventageous PR on T: 01452 260063or email: Rebecca@eventspr.co.uk All press releases and jacket covers are available for download from the Haynes website visit http://www.haynes.co.uk/Press/