2007 YAMAHA YZ125LC oil

1-14
GEN
INFO
STARTING AND BREAK-IN
EC194001
BREAK-IN PROCEDURES
1. Before starting the engine, fill the fuel tank
with a break-in oil-fuel mixture as follows.
2. Perform the pre-operation checks on the
machine.
3. Start and warm up the engine. Check the
idle speed, and check the operation of the
controls and the “ENGINE STOP” button.
4. Operate the machine in the lower gears at
moderate throttle openings for five to eight
minutes. Stop and check the spark plug con-
dition; it will show a rich condition during
break-in.
5. Allow the engine to cool. Restart the engine
and operate the machine as in the step
above for five minutes. Then, very briefly
shift to the higher gears and check full-throt-
tle response. Stop and check the spark
plug.
6. After again allowing the engine to cool,
restart and run the machine for five more
minutes. Full throttle and the higher gears
may be used, but sustained full-throttle op-
eration should be avoided. Check the spark
plug condition.
7. Allow the engine to cool, remove the top
end, and inspect the piston and cylinder.
Remove any high spots on the piston with
#600 grit wet sandpaper. Clean all compo-
nents and carefully reassemble the top end.
8. Drain the break-in oil-fuel mixture from the
fuel tank and refill with the specified mix.
9. Restart the engine and check the operation
of the machine throughout its entire operat-
ing range. Stop and check the spark plug
condition. Restart the machine and operate
it for about 10 to 15 more minutes. The ma-
chine will now be ready to race.
Mixing oil: Mixing ratio:
Yamalube “2-R” 15:1
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1-18
GEN
INFO
CLEANING AND STORAGE
EC1B2001
STORAGE
If your machine is to be stored for 60 days or
more, some preventive measures must be taken
to avoid deterioration. After cleaning the ma-
chine thoroughly, prepare it for storage as fol-
lows:
1. Drain the fuel tank, fuel lines, and the carbu-
retor float bowl.
2. Remove the spark plug, pour a tablespoon
of SAE 10W-30 motor oil in the spark plug
hole, and reinstall the plug. With the engine
stop switch pushed in, kick the engine over
several times to coat the cylinder walls with
oil.
3. Remove the drive chain, clean it thoroughly
with solvent, and lubricate it. Reinstall the
chain or store it in a plastic bag tied to the
frame.
4. Lubricate all control cables.
5. Block the frame up to raise the wheels off
the ground.
6. Tie a plastic bag over the exhaust pipe out-
let to prevent moisture from entering.
7. If the machine is to be stored in a humid or
salt-air environment, coat all exposed metal
surfaces with a film of light oil. Do not apply
oil to rubber parts or the seat cover.
NOTE:
Make any necessary repairs before the machine
is stored.
1C3-9-32-1B 4/5/06 5:26 PM Page 16

2-1
SPECGENERAL SPECIFICATIONS
Model name: YZ125W1 (USA, CDN)
YZ125 (EUROPE, ZA)
YZ125W (AUS, NZ)
Model code number: 1C39 (USA, CDN)
1C3A (EUROPE)
1C3C (AUS, NZ, ZA)
Dimensions: USA, AUS, NZ, ZA EUROPE, CDN
Overall length 2,135 mm 2,139 mm
(84.1 in) (84.2 in)
Overall width 827 mm←
(32.6 in)
Overall height 1,315 mm 1,318 mm
(51.8 in) (51.9 in)
Seat height 997 mm 998 mm
(39.3 in) (39.3 in)
Wheelbase 1,443 mm←
(56.8 in)
Minimum ground clearance 386 mm 388 mm
(15.2 in) (15.3 in)
Dry weight:
Without oil and fuel 86.0 kg (189.6 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 8.6~10.7 : 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 0.66 L (0.58 Imp qt, 0.69 US qt)
Total amount 0.70 L (0.62 Imp qt, 0.74 US qt)
Coolant capacity (including all routes): 0.9 L (0.79 Imp qt, 0.95 US qt)
Air filter: Wet type element
Fuel:
Type Premium unleaded gasoline
only with a research octane
number of 95 or higher
Tank capacity 8.0 L (1.76 Imp gal, 2.11 US gal)
EC200000
SPECIFICATIONSEC211000
GENERAL SPECIFICATIONS
1C3-9-32-2A 4/29/06 10:17 AM Page 2

2-2
SPECGENERAL SPECIFICATIONS
Carburetor:
Type/Manufacturer TMXχ
38SS/MIKUNI
Spark plug:
Type/Manufacturer BR9EVX/NGK (resistance type)
Gap 0.6~0.7 mm (0.024~0.028 in)
Clutch type: Wet, multiple-disc
Transmission:
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, NZEUROPE,CDN
Frame type Semi double cradle←
Caster angle 25.5° 25.6°
Trail 105 mm (4.13 in) 107 mm (4.21 in)
T ire:
Type With tube
Size (front) 80/100-21 51M
Size (rear) 100/90-19 57M
T ire pressure (front and rear) 100 kPa (1.0 kgf/cm2, 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
2
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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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2-7
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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2-11
SPECMAINTENANCE SPECIFICATIONS
EC212300
ELECTRICAL
Part to be tightened Thread size Q’tyT ightening torqueNm m•kg ft•lb
Stator M 6 ×1.0 3 7 0.7 5.1
Rotor M12 ×1.25 1 56 5.6 40
Ignition coil M 6 ×1.0 2 7 0.7 5.1
Item Standard Limit
Ignition system:
Ignition timing (B.T.D.C.) 0.48 mm (0.019 in)…
Advancer type Electrical…
CDI:
Magneto-model (stator)/Manufacturer 1C3-10/YAMAHA…
Source coil 1 resistance (color) 720~1,080 Ωat 20°C (68°F)…
(Green/White-Black/Red)
Source coil 2 resistance (color) 44~66 Ωat 20°C (68°F)…
(Black-Green/Blue)
Pickup coil resistance (color) 248~372 Ωat 20°C (68°F)…
(White/Blue-White/Red)
CDI unit-model/Manufacturer 1C3-10/YAMAHA…
Ignition coil:
Model/Manufacturer 1C3-00/YAMAHA…
Minimum spark gap 6 mm (0.24 in)…
Primary winding resistance 0.24~0.36 Ωat 20°C (68°F)…
Secondary winding resistance 5.7~8.5kΩat 20°C (68°F)…
Spark plug cap:
Resistance 4~6 kΩat 20°C (68°F)…
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