2001 YAMAHA YZ125LC length

5. GASOLINE IS HIGHLY FLAMMABLE.
Always turn off the engine while refuel-
ing. Take care to not spill any gasoline
on the engine or exhaust system.
Never refuel in the vicinity of an open
flame, or while smoking.
6. GASOLINE CAN CAUSE INJURY.
If you should swallow some gasoline,
inhale excess gasoline vapors, or allow
any gasoline to get into your eyes,
contact a doctor immediately. If any
gasoline spills onto your skin or cloth-
ing, immediately wash skin areas with
soap and water, and change your
clothes.
7. ONLY OPERATE THE MACHINE IN AN
AREA WITH ADEQUATE VENTILATION.
Never start the engine or let it run for
any length of time in an enclosed area.
Exhaust fumes are poisonous. These
fumes contain carbon monoxide,
which by itself is odorless and color-
less.
Carbon monoxide is a dangerous gas
which can cause unconsciousness or
can be lethal.
8. PARK THE MACHINE CAREFULLY;
TURN OFF THE ENGINE.
Always turn off the engine if you are
going to leave the machine. Do not
park the machine on a slope or soft
ground as it may fall over.
9. PROPERLY SECURE THE MACHINE
BEFORE TRANSPORTING IT.
When transporting the machine in an-
other vehicle, always be sure it is prop-
erly secured and in an upright position
and that the fuel cock is in the “OFF”
5MV-9-30-0 6/19/00 2:05 PM Page 6

EC083000
MANUAL FORMAT
All of the procedures in this manual are organized in a sequential, step-by-step format. The informa-
tion has been complied to provide the mechanic with an easy to read, handy reference that contains
comprehensive explanations of all disassembly, repair, assembly, and inspection operations.
In this revised format, the condition of a faulty component will precede an arrow symbol and the
course of action required will follow the symbol, e.g.,
9Bearings
Pitting/DamageÕReplace.
EC084002
HOW TO READ DESCRIPTIONS
To help identify parts and clarify procedure steps, there are exploded diagrams at the start of each re-
moval and disassembly section.
1. An easy-to-see exploded diagram 1is provided for removal and disassembly jobs.
2. Numbers 2are given in the order of the jobs in the exploded diagram. A number that is enclosed
by a circle indicates a disassembly step.
3. An explanation of jobs and notes is presented in an easy-to-read way by the use of symbol marks
3. The meanings of the symbol marks are given on the next page.
4. A job instruction chart 4accompanies the exploded diagram, providing the order of jobs, names
of parts, notes in jobs, etc.
5. Extent of removal 5is provided in the job instruction chart to save the trouble of an unnecessary
removal job.
6. For jobs requiring more information, the step-by-step format supplements 6are given in addition
to the exploded diagram and job instruction chart.
4-30
ENGCLUTCH AND PRIMARY DRIVEN GEAR
Extent of removal Order Part name Q’ty Remarks
CLUTCH PLATE AND
FRICTION PLATE REMOVAL
Preparation for Drain the transmission oil.
Refer to “TRANSMISSION OIL REPLACE-removalMENT“ section in the CHAPTER 3.Bolt (brake pedal) Shift the brake pedal downward.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Screw (clutch spring) 5
3 Clutch spring 5
4 Pressure plate 1
5 Push rod 1
6 Plain washer 2
7 Bearing 1
8 Friction plate 8
9 Clutch plate 7
Extent of removal:1Clutch plate and friction plate removal
EC490000CLUTCH AND PRIMARY DRIVEN GEAREC498000CLUTCH PLATE AND FRICTION PLATE
1
10 Nm (1.0 m•kg, 7.2 ft•lb)
10 Nm (1.0 m•kg, 7.2 ft•lb)
4-32
ENGCLUTCH AND PRIMARY DRIVEN GEAREC493000REMOVAL POINTSEC483211Clutch boss1. Remove:
9Nut 1
9Lock washer 2
9Clutch boss 3
NOTE:Straighten the lock washer tab and use the
clutch holding tool 4, 5to hold the clutch boss.
Œ
For USA and CDN
º
Except for USA and CDN
EC494000INSPECTIONEC484100Clutch housing and boss1. Inspect:
9Clutch housing 1
Cracks/Wear/Damage Õ Replace.
9Clutch boss 2
Scoring/Wear/Damage ÕReplace.
EC484201Primary driven gear1. Check:
9Circumferential play
Free play exists ÕReplace.
9Gear teeth a
Wear/ Damage ÕReplace.
EC484400Clutch spring1. Measure:
9Clutch spring free length a
Out of specification ÕReplace springs as
a set.
Clutch holding tool:
YM-91042................................4 4
90890-04086............................5 5
Clutch spring free length:
Standard
40.1 mm 38.1 mm
(1.579 in) (1.500 in)
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1
2
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56
5MV-9-30-0 6/19/00 2:05 PM Page 12

2-1
SPECGENERAL SPECIFICATIONS
Model name: YZ125LC (EUROPE)
YZ125N1 (USA)
YZ125(N) (CDN, AUS, NZ, ZA)
Model code number: 5MV1 (USA, CDN, ZA)
5MV2 (EUROPE)
5MV4 (AUS, NZ)
Dimensions:USA, CDN, ZAEUROPE AUS, NZ
Overall length 2,139 mm 2,136 mm 2,139 mm
(84.2 in) (84.1 in) (84.2 in)
Overall width 827 mm¬¬
(32.6 in)
Overall height 1,318 mm 1,313 mm 1,314 mm
(51.9 in) (51.7 in) (51.7 in)
Seat height 993 mm 994 mm 993mm
(39.1 in) (39.1 in) (39.1 in)
Wheelbase 1,444 mm¬¬
(56.9 in)
Minimum ground clearance 400 mm¬¬
(15.7 in)
Basic weight:
With oil and full fuel tank 95.0 kg (209.4 lb)
Engine:
Engine type Liquid cooled 2-stroke, gasoline
Cylinder arrangement Single cylinder, forward inclined
Displacement 124 cm
3(4.36 lmp oz, 4.19 US oz)
Bore ´Stroke 54 ´54.5 mm (2.126 ´2.146 in)
Compression ratio 8.7~10.8 : 1
Starting system Kick starter
Lubrication system: Premix (30 : 1)(Yamalube 2-R)
Oil type or grade (2-Cycle):
Transmission oil Yamalube 4 (10W-30) or SAE 10W-30 type SE
motor oil
Periodic oil change 0.65 L (0.57 Imp qt, 0.69 US qt)
Total amount 0.70 L (0.62 Imp qt, 0.74 US qt)
Coolant capacity (including all routes): 1.00 L (0.88 Imp qt, 1.06 US qt)
Air filter: Wet type element
Fuel:
Type Except for AUS: Premium unleaded fuel
with a research octane
number of 95 or higher
For AUS: Unleaded fuel only
Tank capacity 8.0 L (1.76 Imp gal, 2.11 US gal)
EC200000
SPECIFICATIONSEC211000
GENERAL SPECIFICATIONS
2
5MV-9-30-2A 6/19/00 1:15 PM Page 2

2-3
SPECMAINTENANCE SPECIFICATIONS
Item Standard Limit
Cylinder head:
Combustion chamber capacity 10.2 cm
3…
(0.359 Imp oz, 0.345 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 1.0 mm (0.039 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=2.15 mm (0.085 in)…
End gap (installed) 0.5~0.7 mm (0.020~0.028 in) 1.2 mm (0.047 in)
Side clearance (installed) 0.035~0.080 mm 0.1 mm (0.004 in)
(0.0014~0.0031 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” 0.20~0.70 mm (0.008~0.028 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 0.20~0.25 mm (0.008~0.010 in) …
Clutch housing radial clearance 0.015~0.049 mm …
(0.0006~0.0019 in)
Clutch release method Outer pull, rack and pinion pull …
EC212000
MAINTENANCE SPECIFICATIONSEC212100
ENGINE
5MV-9-30-2A 6/19/00 1:15 PM Page 4

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
460 mm (18.1 in)¬455 mm (17.9 in)
Spring rate, STD K=4.10 N/mm K=Approx.…
(0.410 kg/mm, 4.10 N/mm
23.0 lb/in) (0.410 kg/mm,
23.0 lb/in)
Optional spring/Spacer Yes¬…
Oil capacity 573 cm
3¬…
(20.2 Imp oz,
19.4 US oz)
Oil level
135 mm (5.31 in)¬…
80~150 mm ¬…
(From top of outer tube with inner tube(3.15~5.91 in)
and damper rod fully compressed
without spring.)
Oil grade Suspension oil ¬…
“01”
Inner tube outer diameter 46 mm (1.81 in)¬…
Front fork top end 5 mm (0.20 in)¬…
Rear suspension: USA, CDN, ZA
EUROPE
AUS, NZ
Shock absorber travel
132 mm (5.20 in)¬…
Spring free length
260 mm (10.24 in) 275 mm (10.83 in)…
Fitting length
248 mm (9.76 in)262 mm (10.31 in)…

242~260 mm 257~275 mm…
(9.53~10.24 in)
(10.12~10.83 in)
Spring rate, STD K=46.0 N/mm K=Approx.…
(4.60 kg/mm, 48.0 N/mm
257.6 lb/in) (4.80 kg/mm,
268.8 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)
5MV-9-30-2A 6/19/00 1:15 PM Page 8

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 40~50 mm (1.6~2.0 in) …
Chain length (10 links) … 152.5 mm (6.004 in)
Front disc brake:
Disc outside dia. ´Thickness 250 ´3.0 mm (9.84 ´0.12 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 240 ´4.0 mm (9.45 ´0.16 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. 12.7 mm (0.500 in)…
Caliper cylinder insdie dia. 27.0 mm (1.063 in)…
Brake fluid type DOT #4…
Brake lever & brake pedal:
Brake lever position 95 mm (3.74 in)…
Brake pedal height 5 mm (0.20 in)…
(vertical height above footrest top)
Clutch lever free play (at lever pivot) 2~4 mm (0.08~0.16 in)…
Throttle grip free play 3~5 mm (0.12~0.20 in)…
5MV-9-30-2A 6/19/00 1:15 PM Page 9

2-12
SPEC
GENERAL TORQUE SPECIFICATIONS/
DEFINITION OF UNITS
This chart specifies torque for standard faste-
ners with standard I.S.O. pitch threads. Torque
specifications for special components or assem-
blies are included in the applicable sections of
this book. To avoid warpage, tighten multi-faste-
ner assemblies in a crisscross fashion, in pro-
gressive stages, until full torque is reached.
Unless otherwise specified, torque specifications
call for clean, dry threads. Components should
be at room temperature.
A: Distance across flats
B: Outside thread diameter
EC230000
DEFINITION OF UNITS
EC220001
GENERAL TORQUE SPECIFICATIONS
A B TORQUE SPECIFICATION
(Nut) (Bolt)
Nm m•kg ft•lb
10 mm 6 mm 6 0.6 4.3
12 mm 8 mm 15 1.5 11
14 mm 10 mm 30 3.0 22
17 mm 12 mm 55 5.5 40
19 mm 14 mm 85 8.5 61
22 mm 16 mm 130 13 94
Unit Read Definition Measure
mm milimeter 10-
3meter Length
cm centimeter 10-2meter Length
kg kilogram 103gram Weight
N Newton 1 kg ´m/sec2Force
Nm Newton meter N ´m Torque
m•kg Meter kilogrma m ´kg Torque
Pa Pascal N/m2Pressure
N/mm Newton per millimeter N/mm Spring rate
L Liter — Volume or capacity
cm3Cubic centimeter — Volume or capacity
r/min Revolution per minute — Engine speed
5MV-9-30-2A 6/19/00 1:15 PM Page 13

3-24
SPROCKETS INSPECTION/DRIVE CHAIN INSPECTION
INSP
ADJ
EC368000
SPROCKETS INSPECTION
1. Inspect:
9Sprocket teeth a
Excessive wear ÕReplace.
NOTE:
Replace the drive, driven sprockets and drive
chain as a set.
EC369002
DRIVE CHAIN INSPECTION
1. Remove:
9Master link clip
9Joint 1
9Drive chain 2
2. Clean:
9Drive chain
Place it in kerosene, and brush off as much
dirt as possible. Then remove the chain
from the kerosene and dry the chain.
3. Measure:
9Drive chain length (10 links) a
Out of specificationÕReplace.
4. Check:
9Drive chain stiffness a
Clean and oil the chain and hold as
illustrated.
StiffÕReplace drive chain.
Drive chain length (10 links):
Limit: 152.5 mm (6.004 in)
5MV-9-30-3B 6/19/00 1:49 PM Page 12