2011 YAMAHA YZ125LC ABS

CONTENTS
CHAPTER 1
GENERAL INFOR-
MATION
LOCATION OF IMPORTANT
LABELS............................ 1-1
DESCRIPTION ................. 1-5
CONSUMER
INFORMATION................. 1-6
INCLUDED PARTS .......... 1-6
IMPORTANT
INFORMATION................. 1-6
CHECKING OF
CONNECTION .................. 1-7
SPECIAL TOOLS ............. 1-8
CONTROL
FUNCTIONS ................... 1-11
STARTING AND
BREAK-IN ...................... 1-12
TORQUE-CHECK
POINTS........................... 1-13
CLEANING AND
STORAGE ...................... 1-14
CHAPTER 2
SPECIFICATIONS
GENERAL
SPECIFICATIONS ............ 2-1
MAINTENANCE
SPECIFICATIONS ............ 2-2
TIGHTENING TORQUES . 2-7
CABLE ROUTING
DIAGRAM ....................... 2-12
CHAPTER 3
REGULAR INSPEC-
TION AND AD-
JUSTMENTS
MAINTENANCE
INTERVALS ...................... 3-1
PRE-OPERATION
INSPECTION AND
MAINTENANCE................ 3-5
ENGINE ............................ 3-6
CHASSIS .......................... 3-9
ELECTRICAL ................. 3-19
CHAPTER 4
ENGINE
SEAT, FUEL TANK AND
SIDE COVERS.................. 4-1
EXHAUST PIPE AND
SILENCER ........................ 4-3
RADIATOR ....................... 4-5
CARBURETOR AND
REED VALVE ................... 4-7
CYLINDER HEAD, CYLIN-
DER AND PISTON ......... 4-12
CLUTCH ......................... 4-19
KICK SHAFT AND
SHIFT SHAFT ................. 4-23
YPVS GOVERNOR......... 4-28
WATER PUMP................ 4-30
CDI MAGNETO............... 4-33
ENGINE REMOVAL ....... 4-35
CRANKCASE AND
CRANKSHAFT ............... 4-39
TRANSMISSION, SHIFT
CAM AND SHIFT
FORK .............................. 4-44
CHAPTER 5
CHASSIS
FRONT WHEEL AND
REAR WHEEL ..................5-1
FRONT BRAKE AND
REAR BRAKE ..................5-6
FRONT FORK .................5-16
HANDLEBAR..................5-24
STEERING ......................5-29
SWINGARM ....................5-33
REAR SHOCK
ABSORBER ....................5-38
CHAPTER 6
ELECTRICAL
ELECTRICAL
COMPONENTS AND
WIRING DIAGRAM ...........6-2
IGNITION SYSTEM...........6-3
CHAPTER 7
TUNING
ENGINE.............................7-1
CHASSIS ..........................7-6

1-13
TORQUE-CHECK POINTS
TORQUE-CHECK POINTS
Concerning the tightening torque, refer to "TIGHTENING TORQUES" section in the CHAPTER 2.
Frame construction Frame to rear frame
Combined seat and fuel tank Fuel tank to frame
Exhaust system Silencer to rear frame
Engine mounting Frame to engine
Engine bracket to engine
Engine bracket to frame
Steering Steering stem to handlebar Steering stem to frame
Steering stem to upper bracket
Upper bracket to handlebar
Suspension Front Steering stem to front fork Front fork to upper bracket
Front fork to lower 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 Tightening of pivot shaft
Wheel Installation of wheel Front Tightening of wheel axle
Tightening of axle holder
Rear Tightening of wheel axle
Wheel to rear wheel sprocket
Brake Front Brake caliper to front fork
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to handlebar
Tightening of bleed screw
Tightening of brake hose holder
Rear Brake pedal to frame
Brake disc to wheel
Tightening of union bolt
Brake master cylinder to frame
Tightening of bleed screw
Tightening of brake hose holder
Fuel system Fuel tank to fuel cock

2-2
MAINTENANCE SPECIFICATIONS
MAINTENANCE SPECIFICATIONS
ENGINETransmission:
Primary reduction system Gear
Primary reduction ratio 64/19 (3.368)
Secondary reduction system Chain drive
Secondary reduction ratio 48/13 (3.692)
Transmission type Constant mesh, 6-speed
Operation Left foot operation
Gear ratio:
1st 31/13 (2.385)
2nd 29/15 (1.933)
3rd 27/17 (1.588)
4th 23/17 (1.353)
5th 24/20 (1.200)
6th 23/21 (1.095)
Chassis: USA, ZA, AUS, NZ EUROPE, CDN
Frame type Semi double cradle←
Caster angle 25.5 ° 25.6 °
Trail 105 mm (4.13 in) 107 mm (4.21 in)
Tire:
Type With tube
Size (front) 80/100-21 51M
Size (rear) 100/90-19 57M
Tire pressure (front and rear) 100 kPa (1.0 kgf/cm
2, 15 psi)
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 Swingarm (link type monocross suspension)
Shock absorber:
Front shock absorber Coil spring/oil damper
Rear shock absorber Coil spring/gas, oil damper
Wheel travel:
Front wheel travel 300 mm (11.8 in)
Rear wheel travel 315 mm (12.4 in)
Electrical:
Ignition system CDI magneto
Item Standard Limit
Cylinder head:
Combustion chamber capacity 8.4 cm
3 (0.296 Imp oz, 0.284 US oz) ----
Warp limit ---- 0.03 mm
(0.0012 in)

2-5
MAINTENANCE SPECIFICATIONS
CHASSISCooling:
Radiator core size:
Width 107.8 mm (4.24 in) ----
Height (left) 240 mm (9.45 in) ----
Height (right) 220 mm (8.66 in) ----
Thickness 32 mm (1.26 in) ----
Radiator cap opening pressure 95–125 kPa (0.95–1.25 kg/cm
2, 13.5–17.8 psi) ----
Radiator capacity (total) 0.56 L (0.49 Imp qt, 0.59 US qt) ----
Water pump:
Type Single-suction centrifugal pump ----
Item Standard Limit
Steering system:
Steering bearing typeTaper roller bearing ----
Front suspension: USA, CDN, ZA, AUS,
NZEUROPE
Front fork travel 300 mm (11.8 in)←----
Fork spring free length 454 mm (17.9 in)←449 mm (17.7
in)
Spring rate, STD K=4.1 N/mm (0.418 kg/
mm, 23.4 lb/in)←----
Optional spring Yes←----
Oil capacity 524 cm
3 (18.4 Imp oz,
17.7 US oz)526 cm3 (18.5 Imp oz,
17.8 US oz)----
Oil grade Suspension oil "S1"←----
Inner tube outer diameter 48 mm (1.89 in)←----
Front fork top end 5 mm (0.2 in)←----
Rear suspension: USA, CDN, ZA, AUS,
NZEUROPE
Shock absorber travel 131.5 mm (5.18 in)←----
Spring free length Approx.265 mm (10.43
in)←----
Fitting length*----
I.D. mark (Red/1) 258 mm (10.16 in) 252 mm (9.92 in) ----
I.D. mark (Red/2) 264 mm (10.39 in) 258 mm (10.16 in) ----
I.D. mark (Red/3) 255.5 mm (10.06 in) 249.5 mm (9.82 in) ----
Preload length
1.5–18 mm (0.06–0.71
in)←----
Spring rate, STD K=46.0 N/mm (4.70 kg/
mm, 263.2 lb/in)←----
Optional spring Yes←----
Enclosed gas pressure 1,000 kPa (10 kg/cm
2,
142 psi)←----
* Spring specification varies according to the differ-
ence in the production lot.Item Standard Limit

2-10
TIGHTENING TORQUES
1. First, tighten the steering ring nut approximately 38 Nm (3.8 m•kg, 27 ft•lb) by using the steering nut wrench, then loosen
the steering ring nut one turn.
2. Retighten the steering ring nut 7 Nm (0.7 m•kg, 5.1 ft•lb).
ELECTRICAL △Engine bracket and frame M8 × 1.25 2 34 3.4 24
△Engine bracket and engine M8 × 1.25 1 34 3.4 24
△Pivot shaft and nut M16 × 1.5 1 85 8.5 61
△Relay arm and swingarm M14 × 1.5 1 70 7.0 50
△Relay arm and connecting rod M14 × 1.5 1 80 8.0 58
△Connecting rod and frame M14 × 1.5 1 80 8.0 58
△Rear shock absorber and frame M10 × 1.25 1 56 5.6 40
△Rear shock absorber and relay arm M10 × 1.25 1 53 5.3 38
△Rear frame and frame (upper) M8 × 1.25 1 32 3.2 23
△Rear frame and frame (lower) M8 × 1.25 2 29 2.9 21
△Swingarm and brake hose holder M5 × 0.8 4 3 0.3 2.2
Swingarm and patch M4 × 0.7 4 2 0.2 1.4
Drive chain tensioner M8 × 1.25 2 16 1.6 11
Drive chain support and swingarm M6 × 1.0 3 7 0.7 5.1
Seal guard and swingarm M5 × 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 bracket M6 × 1.0 1 7 0.7 5.1
Fuel tank and hooking screw (fitting band) M6 × 1.0 1 7 0.7 5.1
Fuel tank and fuel tank bracket M6 × 1.0 4 7 0.7 5.1
△Air scoop and fuel tank M6 × 1.0 4 7 0.7 5.1
△Air scoop and radiator guard (lower) M6 × 1.0 2 6 0.6 4.3
△Front fender M6 × 1.0 4 7 0.7 5.1
△Rear fender (front) M6 × 1.0 2 7 0.7 5.1
△Rear fender (rear) M6 × 1.0 2 12 1.2 8.7
△Side cover M6 × 1.0 2 7 0.7 5.1
Seat M8 × 1.25 2 19 1.9 13
△Number plate M6 × 1.0 1 7 0.7 5.1Part to be tightened Thread size Q'tyTightening torque
Nm m•kg ft•lb
Part to be tightened Thread size Q'tyTightening torque
Nm m•kg ft•lb
Stator M6 × 1.0 3 7 0.7 5.1
Rotor M12 × 1.25 1 56 5.6 40
Ignition coil M6 × 1.0 2 7 0.7 5.1

2-13
CABLE ROUTING DIAGRAM
D. Install the ignition coil, side core
and ground lead together to the
frame. Take care to fasten the
ground lead so that its terminal
is within the indicated range.
E. Clamp the throttle cable and
high tension cord to the frame.
F. Clamp the clutch cable to the left
engine bracket. Clamp the
clutch cable below the position-
ing grommet.
G. Pass the air vent hose back of
the throttle cable.
H. Pass the air vent hose, overflow
hose and crankcase breather
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 inside
the YPVS breather hose.
J. Clamp the CDI magneto lead,
radiator breather hose and
YPVS breather hose to the
frame.
K. Clamp to the frame the CDI
magneto lead and radiator
breather hose. Take care to
clamp them above the projection
on the frame.
L. Locate the clamp ends in the ar-
rowed range.
M. Pass the air vent hose, overflow
hose and crankcase breather
hose so that they do not contact
the rear shock absorber.
N. Bring the connector cover into
contact with the coupler.

2-16
CABLE ROUTING DIAGRAM
1. Master cylinder
2. Brake hose holder
3. Brake hose
A. Install the brake hose so that its
pipe portion 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. Install the brake hose so that its
pipe portion directs as shown
and lightly touches the projec-
tion on the master cylinder.

3-3
MAINTENANCE INTERVALS
BRAKES
Adjust lever position and
pedal height●●
Lubricate pivot point●●
Check brake disc surface●●
Check fluid level and leak-
age●●
Retighten brake disc bolts,
caliper bolts, master cylin-
der bolts and union bolts●●
Replace pads●
Replace brake fluid●Every one year
FRONT FORKS
Inspect and adjust●●
Replace oil●●Suspension oil "S1"
Replace oil seal●
FRONT FORK OIL SEAL
AND DUST SEAL
Clean and lube●●Lithium base grease
PROTECTOR GUIDE
Replace●
REAR SHOCK ABSORBER
Inspect and adjust●●
Lube●(After rain
ride)●Molybdenum disulfide grease
Replace spring seat●Every one year
Retighten●●
DRIVE CHAIN GUIDE AND
ROLLERS
Inspect●●
SWINGARM
Inspect, lube and retighten●●Molybdenum disulfide grease
RELAY ARM, CONNECT-
ING ROD
Inspect, lube and retighten●●Molybdenum disulfide grease
STEERING HEAD
Inspect free play and re-
tighten●●
Clean and lube●Lithium base grease
Replace bearing● ItemAfter
break-in
Every
race
(about
2.5
hours)Every
third
(about
7.5
hours)Every
fifth
(about
12.5
hours)
As re-
quiredRemarks