Page 52 of 576
1-12
GEN
INFO
FUEL AND ENGINE MIXING OIL
EC160051
FUEL AND ENGINE MIXING OIL
Mix oil with the gas at the ratio specified below.
Always use fresh, name-brand gasoline, and mix
the oil and gas the day of the race. Do not use
premix that is more than a few hours old.
NOTE:
If knocking or pinging occurs, use a different
brand of gasoline or higher octane grade.
cC
Never mix two types of oil in the same
batch; clotting of the oil could result. If you
wish to change oil types, be sure to drain
the fuel tank and the carburetor float bowl
of old premix prior to filling with the new
type.
Fuel tank capacity:
8.0 L (1.76 Imp gal, 2.11 US gal)
Mixing oil
Recommended oil:
Yamalube “2-R”
(Yamalube racing 2-cycle oil)
Mixing ratio: 30 : 1
If unavailable, use an equivalent
type of oil.
Recommended fuel:
Premium unleaded gasoline
only with a research octane
number of 95 or higher.
1C3-9-32-1B 4/5/06 5:26 PM Page 2
Page 68 of 576

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
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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…
1C3-9-32-2A 4/29/06 10:17 AM Page 5
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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)
1C3-9-32-2A 4/29/06 10:17 AM Page 8
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3-14
INSP
ADJ
PILOT AIR SCREW ADJUSTMENT
4. Remove:
9Oil drain bolt 1
9Oil filler cap 2
Drain the transmission oil.
5. Install:
9Aluminum washer
9Oil drain bolt 1
6. Fill:
9Transmission oil
7. Check:
9Oil leakage
8. Check:
9Transmission oil level
9. Install:
9Oil filler cap 2
EC35L002
PILOT AIR SCREW ADJUSTMENT
1. Adjust:
9Pilot air screw 1
Recommended oil:
Yamalube 4 (10W-30) or SAE
10W-30 type SE motor oil
Oil capacity
(periodic oil change):
0.66 L (0.58 Imp qt, 0.69 US qt)
Adjustment steps:
9Screw in the pilot air screw until it is lightly
seated.
9Back out by the specified number of turns.
Pilot air screw:
2-1/4 turns out
20 Nm (2.0 m•kg, 14 ft•lb)
1C3-9-32-3A 5/1/06 9:02 AM Page 36
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5-33
CHASFRONT FORK
EC555000
ASSEMBLY AND INSTALLATIONEC5551D0
Front fork assembly
1. Wash the all parts in a clean solvent.
2. Stretch the damper assembly fully.
3. Fill:
9Front fork oil 1
To damper assembly.
cC
9Be sure to use recommended fork oil. If
other oils are used, they may have an ex-
cessively adverse effect on the front fork
performance.
9Never allow foreign materials to enter the
front fork.
Recommended oil:
Suspension oil “S1”
Oil capacity:
195cm
3(6.86 Imp oz, 6.59 US oz)
4. After filling, pump the damper assembly 1
slowly up and down (about 200 mm (7.9 in)
stroke) several times to bleed the damper
assembly of air.
NOTE:
Be careful not to excessive full stroke. A
stroke of 200 mm (7.9 in) or more will cause
air to enter. In this case, repeat the steps 2 to
4.
1C3-9-32-5B 4/7/06 2:47 PM Page 16