maintenance YAMAHA YZ125LC 2007 Owners Manual

EC020000
INTRODUCTION
Congratulations on your purchase of a Yamaha
YZ series. This model is the culmination of
Yamaha’s vast experience in the production of
pacesetting racing machines. It represents the
highest grade of craftsmanship and reliability
that have made Yamaha a leader.
This manual explains operation, inspection, ba-
sic maintenance and tuning of your machine. If
you have any questions about this manual or
your machine, please contact your Yamaha deal-
er.
NOTE:
Yamaha continually seeks advancements in
product design and quality. Therefore, while this
manual contains the most current product infor-
mation available at the time of printing, there
may be minor discrepancies between your
machine and this manual. If you have any ques-
tions concerning this manual, please consult
your Yamaha dealer.
w
PLEASE READ THIS MANUAL CAREFULLY
AND COMPLETELY BEFORE OPERATING
THIS MACHINE. DO NOT ATTEMPT TO OP-
ERATE THIS MACHINE UNTIL YOU HAVE
ATTAINED A SATISFACTORY KNOWL-
EDGE OF ITS CONTROLS AND OPERAT-
ING FEATURES AND UNTIL YOU HAVE
BEEN TRAINED IN SAFE AND PROPER
RIDING TECHNIQUES. REGULAR INSPEC-
TIONS AND CAREFUL MAINTENANCE,
ALONG WITH GOOD RIDING SKILLS, WILL
ENSURE THAT YOU SAFELY ENJOY THE
CAPABILITIES AND THE RELIABILITY OF
THIS MACHINE.
1C3-9-32-0 4/28/06 9:45 AM Page 2

EC050000
TO THE NEW OWNER
This manual will provide you with a good basic
understanding of features, operation, and basic
maintenance and inspection items of this ma-
chine. Please read this manual carefully and
completely before operating your new machine.
If you have any questions regarding the opera-
tion or maintenance of your machine, please
consult your Yamaha dealer.
NOTE:
This manual should be considered a permanent
part of this machine and should remain with it
even if the machine is subsequently sold.
EC060000
NOTICE
Some data in this manual may become out-
dated due to improvements made to this
model in the future. If there is any question
you have regarding this manual or your
machine, please consult your Yamaha deal-
er.
Weights of machines without fuel
The minimum weights for motocross ma-
chines are:
for the class 125 cc ........................minimum
88 kg (194 lb)
for the class 250 cc ........................minimum
98 kg (216 lb)
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.
EC070001
F.I.M. MACHINE WEIGHTS:
1C3-9-32-0 4/28/06 9:45 AM Page 8

EC0A0000
CONTENTS
CHAPTER 1
GENERAL INFORMATION
DESCRIPTION............................................1-1
MACHINE IDENTIFICATION......................1-2
IMPORTANT INFORMATION.....................1-3
CHECKING OF CONNECTION..................1-6
SPECIAL TOOLS........................................1-7
CONTROL FUNCTIONS.............................1-9
FUEL AND ENGINE MIXING OIL.............1-12
STARTING AND BREAK-IN.....................1-13
TORQUE-CHECK POINTS.......................1-16
CLEANING AND STORAGE....................1-17
CHAPTER 2
SPECIFICATIONS
GENERAL SPECIFICATIONS....................2-1
MAINTENANCE SPECIFICATIONS...........2-3
GENERAL TORQUE SPECIFICATIONS..2-12
DEFINITION OF UNITS............................2-12
CABLE ROUTING DIAGRAM...................2-13
CHAPTER 3
REGULAR INSPECTION
AND ADJUSTMENTS
MAINTENANCE INTERVALS.....................3-1
PRE-OPERATION INSPECTION AND
MAINTENANCE..........................................3-4
ENGINE.......................................................3-5
CHASSIS...................................................3-17
ELECTRICAL............................................3-39
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1-16
GEN
INFO
TORQUE-CHECK POINTS
EC1A0013
TORQUE-CHECK POINTS
Frame construction Frame to rear frame
Combined seat and tank Fuel tank to frame
Engine mounting Frame to engine
Engine bracket to engine
Engine bracket to frame
Steering Steering shaft to Steering shaft to frame
handlebar Steering shaft to handle crown
Handle crown to handlebar
Suspension Front Steering shaft to Front fork to handle crown
front fork Front fork to under bracket
Rear For link type Assembly of links
Link to frame
Link to shock absorber
Link to swingarm
Rear Installation of shock Shock absorber to frame
absorber
Rear Installation of swingarm Tightening of pivot shaft
Wheel Installation of wheel Front Tightening of front axle
Tightening of axle holder
Rear Tightening of rear axle
Wheel to sprocket
Brake Front Caliper to front fork
Brake disc to wheel
Tightening of union bolt
Master cylinder to handlebar
Tightening of air bleeder
Tightening of brake hose holder
Rear Brake pedal to frame
Brake disc to wheel
Tighening of union bolt
Master cylinder to frame
Tightening of air bleeder
Tightening of brake hose holder
Fuel system Fuel tank to fuel cock
NOTE:
Concerning the tightening torque, refer to “
MAINTENANCE SPECIFICATIONS” section in
the CHAPTER 2.
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2-3
SPECMAINTENANCE SPECIFICATIONS
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)
Cylinder:
Bore size 54.000~54.014 mm 54.1 mm (2.130 in)
(2.1260~2.1265 in)
Taper limit…
0.05 mm (0.0020 in)
Out of round limit…
0.01 mm (0.0004 in)
Piston:
Piston size/ 53.957~53.972 mm…
(2.1243~2.1249 in)
Measuring point* 17.5 mm (0.69 in)…
Piston clearance 0.040~0.045 mm 0.1 mm (0.004 in)
(0.0016~0.0018 in)
Piston offset 0.5 mm (0.019 in)/EX-side…
Piston pin:
Piston pin outside diameter 14.995~15.000 mm 14.975 mm
(0.5904~0.5906 in) (0.5896 in)
Piston ring:
Sectional sketch 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 0.1 mm (0.004 in)
(0.0014~0.0028 in)
Crankshaft:
Crank width “A” 55.90~55.95 mm …
(2.201~2.203 in)
Runout limit “C” 0.03 mm (0.0012 in) 0.05 mm (0.0020 in)
Connecting rod big end
side clearance “D” 0.06~0.64 mm (0.002~0.025 in)…
Small end free play “F” 0.8~1.0 mm (0.031~0.039 in) 2.0 mm (0.08 in)
Clutch:
Friction plate thickness 2.9~3.1 mm (0.114~0.122 in) 2.8 mm (0.110 in)
Quantity 8 …
Clutch plate thickness 1.5~1.7 mm (0.059~0.067 in) …
Quantity 7 …
Warp limit … 0.2 mm (0.008 in)
Clutch spring free length 40.1 mm (1.579 in) 38.1 mm (1.500 in)
Quantity 5 …
Clutch housing thrust clearance 0.15~0.26 mm (0.006~0.010 in) …
Clutch housing radial clearance 0.014~0.046 mm …
(0.0006~0.0018 in)
Clutch release method Inner push, cam push …
EC212000
MAINTENANCE SPECIFICATIONSEC212100
ENGINE
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2-4
SPECMAINTENANCE SPECIFICATIONS
Item Standard Limit
Transmission:
Main axle deflection limit…
0.01 mm (0.0004 in)
Drive axle deflection limit…
0.01 mm (0.0004 in)
Shifter:
Shifting type Cam drum and guide bar…
Guide bar bending limit…
0.05 mm (0.0020 in)
Kick starter type: Kick and mesh type…
Kick clip friction force P=0.8~1.2 kg (1.8~2.6 lb)…
Air filter oil grade (oiled filter): Foam-air-filter oil or equivalent oil…
Carburetor: USA, CDN EUROPEAUS, NZ, ZA
Type/ManufacturerTMXχ
38SS←←
/MIKUNI
I.D. mark 1C35 30 1C36 40 1C37 50…
Main jet (M.J.) #410 #430←…
Jet needle-clip position (J.N.)
6BFY42-74-3 6BFY43-74-3←…
Cutaway (C.A.) 4.0←←…
Pilot jet (P.J.) #40 #45 #40…
Pilot air screw (P.A.S.) 2-1/4←←…
Valve seat size (V.S.) ø3.8 mm ←←…
(0.15 in)
Starter jet (G.S.) #80←←…
Fuel level (F.L.)
9.5~10.5 mm←←…
(0.37~0.41 in)
Reed valve:
Thickness* 0.47 mm (0.019 in)…
Valve stopper height 8.2~8.6 mm (0.323~0.339 in)…
Valve bending limit…
0.2 mm (0.008 in)
Cooling:
Radiator core size:
Width 107.8 mm (4.24 in)…
Height (left) 240 mm (9.45 in)…
(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…
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2-5
SPECMAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q'tyT ightening torqueNm m•kg ft•lb
Spark plug
M14S×1.25 1 20 2.0 14
Cylinder head (nut) M 8 ×1.25 5 28 2.8 20
(stud) M 8 ×1.25 5 13 1.3 9.4
Cylinder (nut) M 8 ×1.25 4 30 3.0 22
(stud) M10 ×1.25 4 13 1.3 9.4
Power valve:
Cover M 5 ×0.8 4 5 0.5 3.6
Link lever M 4 ×0.7 1 4 0.4 2.9
Holder (power valve) M 5 ×0.8 4 8 0.8 5.8
Push rod M 5 ×0.8 1 5 0.5 3.6
Thrust plate M 5 ×0.8 1 4 0.4 2.9
Governor fork M 4 ×0.7 2 5 0.5 3.6
Housing M 5 ×0.8 3 4 0.4 2.9
Water pump housing cover M 6 ×1.0 4 10 1.0 7.2
Coolant drain bolt M 6 ×1.0 1 10 1.0 7.2
Radiator M 6 ×1.0 6 10 1.0 7.2
Radiator panel M 6 ×1.0 2 10 1.0 7.2
Radiator hose clamp M 6 ×1.0 8 2 0.2 1.4
Air filter element M 6 ×1.0 1 2 0.2 1.4
Carburetor joint M 6 ×1.0 4 10 1.0 7.2
Carburetor joint clamp M 4 ×0.7 1 2 0.2 1.4
Air filter joint clamp M 4 ×0.7 1 2 0.2 1.4
Air filter case M 6 ×1.0 4 8 0.8 5.8
Air filter guide clamp M 5 ×0.8 1 4 0.4 2.9
Read valve M 3 ×0.5 6 1 0.1 0.7
Throttle cable adjust bolt and locknut M 8 ×1.25 1 7 0.7 5.1
Throttle cable M 6 ×0.75 1 4 0.4 2.9
Crankcase M 6 ×1.0 12 14 1.4 10
Crankcase cover (right) M 6 ×1.0 8 10 1.0 7.2
Crankcase cover (left) M 6 ×1.0 4 5 0.5 3.6
Chain cover M 6 ×1.0 2 5 0.5 3.6
Bearing plate cover M 6 ×1.0 4 10 1.0 7.2
Holder M 6 ×1.0 1 10 1.0 7.2
Oil check bolt M 6 ×1.0 1 10 1.0 7.2
Oil drain bolt M10 ×1.25 1 20 2.0 14
Kick starter M 6 ×1.0 1 10 1.0 7.2
Cluch cover M 6 ×1.0 6 10 1.0 7.2
Primary drive gear M 8 ×1.25 1 48 4.8 35
Clutch boss M16 ×1.0 1 80 8.0 58
Clutch spring M 6 ×1.0 5 10 1.0 7.2
Clutch cable adjust bolt and locknut M 6 ×0.75 1 4 0.4 2.9
Drive sprocket M18 ×1.0 1 75 7.5 54
Shift pedal M 6 ×1.0 1 12 1.2 8.7
Bearing plate cover (shift cam) M 6 ×1.0 2 10 1.0 7.2
Shift guide M 6 ×1.0 2 10 1.0 7.2
Stopper lever M 6 ×1.0 1 10 1.0 7.2
Segment M 8 ×1.25 1 30 3.0 22
 
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2-6
SPECMAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q'tyT ightening torqueNm m•kg ft•lb
Exhaust pipe M 6 ×1.0 2 12 1.2 8.7
Exhaust pipe stay (front) M 6 ×1.0 1 12 1.2 8.7
Exhaust pipe stay (rear) M 6 ×1.0 1 12 1.2 8.7
Silencer:
Silencer and frame M 6 ×1.0 2 12 1.2 8.7
Fiber (For USA and CDN) M 6 ×1.0 2 10 1.0 7.2
Fiber (Except for USA and CDN) M 6 ×1.0 4 10 1.0 7.2
NOTE:

- marked portion shall be checked for torque tightening after break-in or before each race.


 
 
 
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2-7
SPECMAINTENANCE SPECIFICATIONS
EC212201
CHASSIS
Item Standard Limit
Steering system:
Steering bearing type Taper roller bearing…
Front suspension: USA, CDN, ZA,
EUROPE
AUS, NZ
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=4.0 N/mm←…
(0.408 kg/mm,
22.8 lb/in)
Optional spring Yes←…
Oil capacity 527 cm
3522 cm3…
(18.6 Imp oz, (18.4 Imp oz,
17.8 US oz) 17.6 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,
EUROPE
AUS, NZ
Shock absorber travel
131.5 mm (5.18 in)←…
Spring free length
Approx. 265 mm←…
(10.43 in)
Fitting length
One I.D. mark
256 mm (10.08 in) 254 mm (10.00 in)…
Two I.D. marks
262 mm (10.31 in) 260 mm (10.24 in)…
Three I.D. marks
253.5 mm (9.98 in) 251.5 mm (9.90 in)…

One I.D.mark
245.5 ~ 263.5 mm←…
(9.67 ~ 10.37 in)
Two I.D. marks251.5 ~ 269.5 mm←…
(9.90 ~ 10.61 in)
Three I.D. marks243.0 ~ 261.0 mm←…
(9.57 ~ 10.28 in)
Spring rate, STDK=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)
Swingarm:
Swingarm free play limit
End…
1.0 mm (0.04 in)
Side clearance…
0.2~0.9 mm
(0.008~0.035 in)
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2-8
SPECMAINTENANCE SPECIFICATIONS
Item Standard Limit
Wheel:
Front wheel type Spoke wheel…
Rear wheel type Spoke wheel…
Front rim size/Material 21 ×1.60/Aluminum…
Rear rim size/Material 19 ×1.85/Aluminum…
Rim runout limit:
Radial…
2.0 mm (0.08 in)
Lateral … 2.0 mm (0.08 in)
Drive chain:
Type/Manufacturer DID520DMA2 SDH/DAIDO …
Number of links 111 links+joint …
Chain slack 48~58 mm (1.9~2.3 in) …
Chain length (15 links) … 242.9 mm (9.563 in)
Front disc brake:
Disc outside dia. ×Thickness 250 ×3.0 mm 250 ×2.5 mm
(9.84 ×0.12 in) (9.84 ×0.10 in)
Pad thickness 4.4 mm (0.17 in) 1.0 mm (0.04 in)
Master cylinder inside dia. 11.0 mm (0.433 in)…
Caliper cylinder inside dia. 27.0 mm (1.063 in) ×2…
Brake fluid type DOT #4…
Rear disc brake:
Disc outside dia. ×Thickness 245 ×4.0 mm 245 ×3.5 mm
(9.65 ×0.16 in) (9.65 ×0.14 in)
Deflection limit…
0.15 mm (0.006 in)
Pad thickness 6.4 mm (0.25 in) 1.0 mm (0.04 in)
Master cylinder inside dia. 11.0 mm (0.433 in)…
Caliper cylinder insdie dia. 25.4 mm (1.000 in)…
Brake fluid type DOT #4…
Brake lever & brake pedal:
Brake lever position 95 mm (3.74 in)…
Brake pedal height Zero mm (Zero in)…
(vertical height above footrest top)
Clutch lever free play (lever end) 8~13 mm (0.31~0.51 in)…
Throttle grip free play 3~5 mm (0.12~0.20 in)…
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