2001 YAMAHA YZ125LC fuel filter

1-10
GEN
INFO
CONTROL FUNCTIONS
EC156000
FRONT BRAKE LEVER
The front brake lever 1is located on the right
handlebar. Pull it toward the handlebar to acti-
vate the front brake.
EC157000
REAR BRAKE PEDAL
The rear brake pedal 1is located on the right
side of the machine. Press down on the brake
pedal to activate the rear brake.
EC158001
FUEL COCK
The fuel cock supplies fuel from the tank to car-
buretor while filtering the fuel. The fuel cock has
the two positions:
OFF: With the lever in this position, fuel will not
flow. Always return the lever to this posi-
tion when the engine is not running.
ON: With the lever in this position, fuel flows to
the carburetor. Normal riding is done with
the lever in this position.
EC159000
STARTER KNOB (CHOKE)
When cold, the engine requires a richer air-fuel
mixture for starting. A separate starter circuit,
which is controlled by the starter knob 1, sup-
plies this mixture. Pull the starter knob out to
open the circuit for starting. When the engine
has warmed up, push it in to close the circuit.
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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
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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 engine mixing oil…
Carburetor: USA, CDN, ZA
EUROPE
AUS, NZ
Type/Manufacturer TMXø
38SS¬
/MIKUNI
I.D. mark 5MV1 00 5MV2 10…
Main jet (M.J.) #460 #450…
Jet needle-clip position (J.N.) 6BGK9-75-3 6BHY1-75-3…
Cutaway (C.A.) 5.75¬…
Pilot jet (P.J.) #25 #30…
Pilot air screw (P.A.S.) 1-1/4 1-1/2…
Valve seat size (V.S.)
ø3.8 mm (0.15 in)¬…
Starter jet (G.S.) #80¬…
Fuel level (F.L.) 13.5~14.5 mm ¬
(0.53~0.57 in)
Reed valve:
Thickness* 0.42 mm (0.017 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 110 mm (4.33 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) 0.63 L (0.55 Imp qt, 0.67 US qt)…
Water pump:
Type Single-suction centrifugal pump…
5MV-9-30-2A 6/19/00 1:15 PM Page 5

3-2
MAINTENANCE INTERVALS
INSP
ADJ
Item Remarks
COOLING SYSTEM
Check coolant level and leakagell
Check radiator cap operationl
Replace coolantlEvery two years
Inspect hosesl
OUTSIDE NUTS AND BOLTS Refer to “STARTING
RetightenllAND BREAK-IN” section
in the CHAPTER 1.
AIR FILTER
Clean and lubricatellUse foam air-filter oil
Replacel
FRAME
Clean and inspectll
FUEL TANK, COCK
Clean and inspectll
BRAKES
Adjust lever position and pedal heightll
Lubricate pivot pointll
Check brake disc surfacell
Check fluid level and leakagell
Retighten brake disc bolts, caliper bolts,
ll
master cylinder bolts and union bolts
Replace padsl
Replace brake fluidlEvery one year
FRONT FORKS
Inspect and adjustll
Replace oilllSuspension oil “01”
Replace oil seall
FRONT FORK OIL SEAL AND DUST SEAL
Clean and lubellLithium base grease
REAR SHOCK ABSORBER
Inspect and adjustll
Lube ll
Molybdenum disulfide grease
Retightenll
CHAIN GUARD AND ROLLERS
Inspectll
SWINGARM
Inspect and retightenll
RELAY ARM, CONNECTING ROD
Inspect and lubellMolybdenum disulfide grease
STEERING HEAD
Inspect free play and retightenll
Clean and lubelLithium base grease
Replace bearingl
TIRE, WHEELS
Inspect air pressure, wheel run-out,
ll
tire wear and spoke looseness
Retighten sprocket boltll
Inspect bearingsl
Replace bearingsl
LubricatelLithium base grease
THROTTLE, CONTROL CABLE
Check routing and connectionllYamaha cable lube or
LubricatellSAE 10W-30 motor oil
After
break-
inEvery
raceEvery
thirdEvery
fifthAs re-
quired
3
5MV-9-30-3A 6/19/00 1:52 PM Page 3

4-11
ENGCARBURETOR AND REED VALVE
Measurement and adjustment steps:
9Remove the drain plug.
9Connect the fuel level gauge adapter 2and
fuel level gauge 1to the float chamber.
Fuel level gauge adapter:
YM-01470/90890-01470
Fuel level gauge:
YM-1312-A/90890-01312
9Hold the fuel level gauge vertically next to
the float chamber mating surface.
9Measure the fuel level with the fuel level
gauge.
NOTE:
Keep the carburetor and fuel level gauge ver-
tically when measuring the fuel level.
9If the fuel level is not within specification, in-
spect the valve seat and needle valve.
9If either is worn, replace them both.
9If both are fine, adjust the fuel level by bend-
ing the float tab bon the float.
9Recheck the fuel level.
EC464802
Fuel level
1. Measure:
9Fuel level a
Out of specification ÕAdjust.
Fuel level:
13.5~14.5 mm (0.53~0.57 in)
Above the float chamber
mating surface
EC464A00
Filter
1. Inspect:
9Filter 1
Damage Õ Replace.
NOTE:
Inspect the filter as it is assembled to the carbu-
retor. Do not remove the filter except when
replacing it.
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7-10
TUNSETTING
EC71C020
Road condition and examples of carburetor setting
EC71D040
Examples of carburetor setting depending on symptom
Symptom Setting Checking
At full throttle Increase main jet calibration No. Discoloration of spark plug
Õ
Stall at high speeds (Gradually) If tan color, it is in good condition.
* Hard breathing If can not be normalized:
Shearing noise Clogged float valve seat
Whitish spark plug Clogged fuel hose
Clogged fuel cock
Lean mixture
At full-throttle Decrease main jet calibration No. Discoloration of spark plug Õ
Stop of speed pick-up (Gradually) If tan color, it is in good condition.
Slow speed pick-up *In case of racing slight enrichment If not effect:
of mixture reduces engine trouble. Clogged air cleaner
Slow response Fuel overflow from carburetor
Sooty spark plug Clogged main air passage or clogged
filter
Rich mixture
Lean mixture Lower jet needle clip position.
(1 groove down)
Rich mixture Raise jet needle clip position.
(1 groove up)
1/4~3/4 throttle Lower jet needle clip position.
* Hard breathing (1 groove down)
Lack of speed
1/4~1/2 throttle Raise jet needle clip position.
Slow speed pick-up (1 groove up)
White smoke
Poor acceleration
Conditions General condition Sandy condition
Under 10°C 15~25°C Over 30°C Under 10°C 15~25°C Over 30°C
(50°F) (59~77°F) (86°F) (50°F) (59~77°F) (86°F)
Parts (Winter)(Spring, Autumn)(Summer) (Winter)(Spring, Autumn)(Summer)
Main jet#470 #460 #450 #490 #480 #470
*#460 *#450 *#440 *#470 *#460 *#450
Jet needle6BGK10-75-3 6BGK9-75-3 6BGK9-75-3 6BGK9-75-4 6BGK10-75-3 6BGK10-75-3
*6BHY25-75-3 *6BHY1-75-3 *6BHY1-75-3 *6BHY1-75-4 *6BHY25-75-3 *6BHY25-75-3
Pilot jet#25 #25 #25 #25 #25 #25
*#30 *#30 *#30 *#30 *#30 *#30
Pilot air screw1 1-1/4 1-1/2 1 1-1/4 1-1/2
*1-1/4 *1-1/2 *1-3/4 *1-1/4 *1-1/2 *1-3/4
Leaner
(Standard)
Richer
Õ
Õ
Clip position indicates the position of jet
needle groove, to which the clip is fitted.
The position is numbered from the top.
If a change in the clip position (1
groove) is effective, try another jet nee-
dle that provides a difference of 0.5 in
the clip position.
*For EUROPE
5MV-9-30-7A 6/19/00 1:24 PM Page 24