oil pressure YAMAHA YZ125LC 2007 Owners Manual

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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2-7
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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3-2
MAINTENANCE INTERVALS
INSP
ADJ
Item Remarks
COOLING SYSTEM
Check coolant level and leakage
Check radiator cap operation
Replace coolantEvery two years
Inspect hoses
OUTSIDE NUTS AND BOLTS Refer to “STARTING
RetightenAND BREAK-IN” section
in the CHAPTER 1.
AIR FILTER
Clean and lubricateUse foam air-filter oil or
Replaceequivalent oil
FRAME
Clean and inspect
FUEL TANK, COCK
Clean and inspect
BRAKES
Adjust lever position and pedal height
Lubricate pivot point
Check brake disc surface
Check fluid level and leakage
Retighten brake disc bolts, caliper bolts,

master cylinder bolts and union bolts
Replace pads
Replace brake fluidEvery one year
FRONT FORKS
Inspect and adjust
Replace oilSuspension oil “S1”
Replace oil seal
FRONT FORK OIL SEAL AND DUST SEAL
Clean and lubeLithium base grease
PROTECTOR GUIDE
Replace
REAR SHOCK ABSORBER
(After
Inspect and adjustrain ride)
Lube Molybdenum disulfide grease
Replace spring seatEvery one year
Retighten
CHAIN GUARD AND ROLLERS
Inspect
SWINGARM
Inspect, lube and retightenMolybdenum disulfide grease
RELAY ARM, CONNECTING ROD
Inspect, lube and retightenMolybdenum disulfide grease
STEERING HEAD
Inspect free play and retighten
Clean and lubeLithium base grease
Replace bearing
TIRE, WHEELS
Inspect air pressure, wheel run-out,

tire wear and spoke looseness
Retighten sprocket bolt
Inspect bearings
Replace bearings
LubricateLithium base grease
After
break-
inEvery
raceEvery
thirdEvery
fifthAs re-
quired
3
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3-4
PRE-OPERATION INSPECTION AND MAINTENANCE
INSP
ADJ
EC320000
PRE-OPERATION INSPECTION AND MAINTENANCE
Before riding for break-in operation, practice or a race, make sure the machine is in good operating
condition.
Before using this machine, check the following points.
EC321000
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
Coolant Check that coolant is filled up to the radiator filler cap.
Check the cooling system for leakage.P3-5~9
Fuel Check that a fresh mixture of oil and gasoline is filled in
the fuel tank. Check the fuel line for leakage.P1-12
Transmission oil Check that the oil level is correct. Check the crankcase
for leakage.P3-12~14
Gear shifter and clutch Check that gears can be shifted correctly in order and
that the clutch operates smoothly.P3-9
Throttle grip/Housing Check that the throttle grip operation and free play
are correctly adjusted. Lubricate the throttle grip and P3-10~11
housing, if necessary.
Brakes Check the play of front brake and effect of front and
rear brake.P3-17~23
Chain Check chain slack and alignment. Check that the chain
is lubricated properly.P3-24~26
Wheels Check for excessive wear and tire pressure. Check for
loose spokes and have no excessive play.P3-34~35
Steering Check that the handlebar can be turned smoothly and
have no excessive play.P3-35~37
Front forks and Check that they operate smoothly and there is no oil
rear shock absorber leakage.P3-26~33
Cables (wires) Check that the clutch and throttle cables move smooth-
ly. Check that they are not caught when the handlebars —
are turned or when the front forks travel up and down.
Muffler Check that the muffler is tightly mounted and has no
cracks.P3-15~16
Sprocket Check that the driven sprocket tightening bolt is
not loose.P3-24
Lubrication Check for smooth operation. Lubricate if necessary. P3-38
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P1-16
Lead connectors Check that the CDI magneto, CDI unit, and ignition coil
are connected tightly.P1-6
Settings Is the machine set suitably for the condition of the
racing course and weather or by taking into account the
P7-1~23
results of test runs before racing? Are inspection and
maintenance completely done?
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3-27
FRONT FORK OIL SEAL AND DUST SEAL CLEANING/
FRONT FORK INTERNAL PRESSURE RELIEVING/
FRONT FORK REBOUND DAMPING FORCE ADJUSTMENTINSP
ADJ
EC36D001
FRONT FORK OIL SEAL AND DUST SEAL
CLEANING
1. Remove:
9Protector
9Dust seal 1
NOTE:
Use a thin screw driver, and be careful not to
damage the inner fork tube and dust seal.
2. Clean:
9Dust seal a
9Oil seal b
NOTE:
9Clean the dust seal and oil seal after every run.
9Apply the lithium soap base grease on the in-
ner tube.
EC36H002
FRONT FORK REBOUND DAMPING FORCE
ADJUSTMENT
1. Adjust:
9Rebound damping force
By turning the adjuster 1.
Stiffer a a
Increase the rebound damping
force. (Turn the adjuster 1 1
in.)
Softer b b
Decrease the rebound
damping force. (Turn the
adjuster 1 1
out.)
EC36f000
FRONT FORK INTERNAL PRESSURE
RELIEVING
NOTE:
If the front fork initial movement feels stiff during
a run, relieve the front fork internal pressure.
1. Elevate the front wheel by placing a suitable
stand under the engine.
2. Remove the air bleed screw 1and release
the internal pressure from the front fork.
3. Install:
9Air bleed screw
1 Nm (0.1 m•kg, 0.7 ft•lb)
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4-30
CLUTCH AND PRIMARY DRIVEN GEARENG
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.
Rotor and stator Refer to
“CDI MAGNETO”section.
Clutch cable Disconnect at engine side.
1 Clutch cover 1
2 Screw (clutch spring) 6
3 Clutch spring 6
4 Pressure plate 1
5 Friction plate 8
6 Clutch plate 7
Extent of removal:1Clutch plate and friction plate removal
EC490000
CLUTCH AND PRIMARY DRIVEN GEAREC498000
CLUTCH 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)
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4-35
CLUTCH AND PRIMARY DRIVEN GEARENG
5. Install:
9Friction plate 1
9Clutch plate 2
NOTE:
9Install the clutch plates and friction plates alter-
nately on the clutch boss, starting with a friction
plate and ending with a friction plate.
9Apply the transmission oil on the friction plates
and clutch plates.
6. Install:
9Bearing 1
9Plain washer 2
9Circlip 3
To push rod 1 4.
NOTE:
Apply the lithium soap base grease on the bear-
ing and plain washer.
7. Install:
9Push rod 2 1
9Ball 2
9Push rod 1 3
NOTE:
Apply the transmission oil the push rod 1, 2 and
ball.
8. Install:
9Pressure plate 1
9. Install:
9Clutch spring 1
9Screw (clutch spring) 2
NOTE:
Tighten the screws in stage, using a crisscross
pattern.
10 Nm (1.0 m•kg, 7.2 ft•lb)
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5-34
CHASFRONT FORK
5. Measure:
9Oil level (left and right) a
Out of specification  Adjust.
Standard oil level:
145~148 mm (5.71~5.83 in)
From top of fully stretched
damper assembly.
6. Tighten:
9Locknut 1
NOTE:
Fully finger tighten the locknut onto the
damper assembly.
7. Loosen:
9Compression damping adjuster 1
NOTE:
9Loosen the compression damping adjuster fin-
ger tight.
9Record the set position of the adjuster (the
amount of turning out the fully turned in posi-
tion).
8. Install:
9Base valve 1
To damper assembly 2.
NOTE:
First bring the damper rod pressure to a maxi-
mum. Then install the base valve while releas-
ing the damper rod pressure.
9. Check that the damper assembly is fully
stretched.
Not fully stretched  Repeat the steps 2 to 8.
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5-64
CHASREAR SHOCK ABSORBER
EC586000
HANDLING NOTE
w
This shock absorber is provided with a
separate type tank filled with high-pressure
nitrogen gas. To prevent the danger of ex-
plosion, read and understand the following
information before handling the shock ab-
sorber.
The manufacturer can not be held respon-
sible for property damage or personal in-
jury that may result from improper han-
dling.
1. Never tamper or attempt to disassemble
the cylinder or the tank.
2. Never throw the shock absorber into an
open flame or other high heat. The shock
absorber may explode as a result of ni-
trogen gas expansion and/or damage to
the hose.
3. Be careful not to damage any part of the
gas tank. A damaged gas tank will impair
the damping performance or cause a
malfunction.
4. Take care not to scratch the contact sur-
face of the piston rod with the cylinder;
or oil could leak out.
5. Never attempt to remove the plug at the
bottom of the nitrogen gas tank. It is very
dangerous to remove the plug.
6. When scrapping the shock absorber, fol-
low the instructions on disposal.
EC587000
NOTES ON DISPOSAL (YAMAHA DEAL-
ERS ONLY)
Before disposing the shock absorber, be sure to
extract the nitrogen gas from valve 1. Wear eye
protection to prevent eye damage from escaping
gas and/or metal chips.
w
To dispose of a damaged or worn-out
shock absorber, take the unit to your
Yamaha dealer for this disposal procedure.
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