engine YAMAHA YZ125LC 2003 Owner's Guide

2-17
SPEC
SCHEMA DE CHEMINEMENT DES CABLES
KABELFÜHRUNGSÜBERSICHTPLAN
DIAGRAMMA DEL PASSAGGIO DEI CAVI
1Bremsschlauch
2Hauptbremszylinder
3Leitungskabel des Motorstoppknopfes
„ENGINE STOP“
4Motorstoppknopf „ENGINE STOP“
5Gasseil
6Kupplungskabel
7Klemme
8Kabelführung
ADen Bremsschlauch so einbauen, daß
sein Rohrteil gemäß Abbildung ange-
ordnet ist und den Überstand am
Hauptbremszylinder leicht berührt.
BDas Leitungskabel des Motorstopp-
knopfes „ENGINE STOP“ in der Mitte
des Kupplungshalters durchführen.
CDas Kupplungsseil vor dem Gasseil
durchführen.
DKabel des Motorausschaltknopfes am
Lenker festklemmen mit 3 klicks.
EDen Bremsschlauch vor dem Num-
mernschild und durch die Kabelführung
durchführen.
FDas Kupplungsseil und das Gasseil
über der Nummernschild-Befesti-
gungsnabe überkreuzen.1Tuyau de frein
2Maître-cylindre
3Fil de bouton d’arrêt du moteur “ENGI-
NE STOP”
4Bouton d’arrêt du moteur “ENGINE
STOP”
5Câble d’accélérateur
6Câble d’embrayage
7Bride
8Guide de câble
åIstaller la tuyau de frein de manière que
la partie avec le tuyau soit dirigée
comme indipué et touche légèrement la
saillie sur le maîtrecylindre.
∫Faire passer le fil de bouton d’arrêt du
moteur “ENGINE STOP” au centre du
support d’embrayage.
çFaire passer le câble d’embrayage devant
le câble d’accélérateur.
∂Fixer le fil du bouton “ENGINE STOP”
sur le guidon (3 déclics).
´Faire passer le tuyau de frein devant la
plaque d’immatriculation et à travers le
guide de câble.
ƒCroiser le câble d’embrayage et le câble
d’accélérateur sur le bossage de fixation
de la plaque minéralogique.1Tubo flessibile del freno
2Cilindro principale
3Conduttore del pulsante “ARRESTO
MOTORE”
4Pulsante “ARRESTO MOTORE”
5Cavo dell’acceleratore
6Cavo della frizione
7Nastro
8Guida per cavi
åInstallare il tubo flessibile del freno in
modo che la sua parte di tubo sia rivolta
come illustrato e tocchi leggermente la
sporgenza sul cilindro principale.
∫Far passare il conduttore del pulsante
“ARRESTO MOTORE” nel mezzo del
supporto della frizione.
çFar passare il cavo della frizione davanti
al cavo dell’acceleratore.
∂Bloccare il conduttore del pulsante
“ARRESTO MOTORE” sul manubrio
dopo 3 scatti.
´Far passare il tubo flessibile del freno
davanti alla targa e attraverso la guida
per cavi.
ƒIncrociare il cavo della frizione e il cavo
dell’acceleratore sopra il mozzo della
targa.

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.P3-35~36
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. P3-37
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
P7-1~25
results of test runs before racing? Are inspection and
maintenance completely done?

3-5
INSP
ADJENGINE/COOLANT LEVEL INSPECTION/
COOLANT REPLACEMENT
EC350000
ENGINE
EC351011
COOLANT LEVEL INSPECTION
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Do not remove the radiator cap 1 1
, drain
bolt and hoses when the engine and radia-
tor are hot. Scalding hot fluid and steam
may be blown out under pressure, which
could cause serious injury.
When the engine has cooled, place a thick
towel over the radiator cap, slowly rotate
the cap counterclockwise to the detent.
This procedure allows any residual pres-
sure to escape. When the hissing sound
has stopped, press down on the cap while
turning counterclockwise and remove it.
cC
Hard water or salt water is harmful to the
engine parts. You may use distilled water,
if you can’t get soft water.
1. Place the machine on a level place, and
hold it in an upright position.
2. Remove:
9Radiator cap
3. Check:
9Coolant level a
Coolant level low Add coolant.
1Radiator
EC353011
COOLANT REPLACEMENT
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Do not remove the radiator cap when the
engine is hot.

3-6
INSP
ADJ
COOLANT REPLACEMENT
cC
Take care so that coolant does not splash
on painted surfaces. If it splashes, wash it
away with water.
1. Place a container under the engine.
2. Remove:
9Coolant drain bolt 1
3. Remove:
9Radiator cap
Drain the coolant completely.
4. Clean:
9Cooling system
Thoroughly flush the cooling system with
clean tap water.
5. Install:
9Copper washer
9Coolant drain bolt
6. Fill:
9Radiator
9Engine
To specified level.
Recommended coolant:
High quality ethylene glycol
anti-freeze containing
anti-corrosion for
aluminum engine
Coolant 1 1
and water
(soft water) 2 2
mixing ratio:
50%/50%
Coolant capacity:
0.95 L (0.84 Imp qt, 1.00 US qt)
10 Nm (1.0 m•kg, 7.2 ft•lb)

3-7
INSP
ADJ
RADIATOR CAP INSPECTION
cC
9Do not mix more than one type of ethyl-
ene glycol antifreeze containing corro-
sion inhibitors for aluminum engine.
9Do not use water containing impurities
or oil.
7. Install:
9Radiator cap
Start the engine and warm it up for a sev-
eral minutes.
8. Check:
9Coolant level
Coolant level low Add coolant.
EC355000
RADIATOR CAP INSPECTION
1. Inspect:
9Seal (radiator cap) 1
9Valve and valve seat 2
Crack/Damage Replace.
Exist fur deposits 3Clean or replace.
Handling notes of coolant:
The coolant is harmful so it should be handled
with special care.
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9When coolant splashes to your eye.
Thoroughly wash your eye with water
and see your doctor.
9When coolant splashes to your clothes.
Quickly wash it away with water and then
with soap.
9When coolant is swallowed.
Quickly make him vomit and take him to
a doctor.

3-10
INSP
ADJTHROTTLE CABLE ADJUSTMENT/
THROTTLE LUBRICATION
EC35A001
THROTTLE CABLE ADJUSTMENT
1. Check:
9Throttle grip free play a
Out of specificationAdjust.
2. Adjust:
9Throttle grip free play
EC35S002
THROTTLE LUBRICATION
1. Remove:
9Cap cover 1
9Throttle cable cap 2
2. Apply:
9Lithium soap base grease
On the throttle cable end a, tube guide ca-
ble winding portion band roller sliding
surface c.
Throttle grip free play adjustment steps:
9Loosen the locknut 1.
9Turn the adjuster 2until the specified free
play is obtained.
9Tighten the locknut.
NOTE:
Before adjusting the throttle cable free play,
the engine idle speed should be adjusted.
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After adjusting, turn the handlebar to
right and left and make sure that the en-
gine idling does not run faster.
Throttle grip free play a a
:
3~5 mm (0.12~0.20 in)

3-11
INSP
ADJ
AIR FILTER CLEANING
3. Install:
9Throttle cable cap
9Cap cover
EC35G040
AIR FILTER CLEANING
NOTE:
Proper air filter maintenance is the biggest key
to preventing premature engine wear and dam-
age.
cC
Never run the engine without the air filter
element in place; this would allow dirt and
dust to enter the engine and cause rapid
wear and possible engine damage.
1. Remove:
9Seat
9Fitting bolt 1
9Washer 2
9Air filter element 3
9Filter guide 4
2. Clean:
9Air filter element
Clean them with solvent.
NOTE:
After cleaning, remove the remaining solvent by
squeezing the element.
cC
Do not twist the element when squeezing
the element.
1 Nm (0.1 m•kg, 0.7 ft•lb)

3-12
INSP
ADJ
TRANSMISSION OIL LEVEL CHECK
3. Inspect:
9Air filter element
Damage Replace.
4. Apply:
9Foam-air-filter oil or equivalent oil
To the element.
NOTE:
Squeeze out the excess oil. Element should be
wet but not dripping.
5. Install:
9Filter guide 1
NOTE:
Align the projection aon filter guide with the
hole bin air filter element.
6. Apply:
9Lithium soap base grease
On the matching surface aon air filter ele-
ment.
7. Install:
9Air filter element 1
9Washer
9Fitting bolt
NOTE:
Align the projection aon filter guide with the
hole bin air filter case.
EC35H002
TRANSMISSION OIL LEVEL CHECK
1. Start the engine, warm it up for several min-
utes and wait for five minutes.
2. Place the machine on a level place and hold
it up on upright position by placing the suit-
able stand under the engine.
2 Nm (0.2 m•kg, 1.4 ft•lb)

3-13
INSP
ADJ
TRANSMISSION OIL REPLACEMENT
3. Check:
9Transmission oil level
EC35K002
TRANSMISSION OIL REPLACEMENT
1. Start the engine and warm it up for several
minutes and wait for five minute.
2. Place the machine on a level place and hold
it on upright position by placing the suitable
stand under the engine.
3. Place a suitable container under the engine.
Transmission oil level checking steps:
9Remove the oil check bolt 1.
9Inspect the oil level.
NOTE:
Be sure the machine is positioned straight
up when inspecting the oil level.
w
Never attempt to remove the oil check bolt
just after high speed operation. The heat-
ed oil could spout out, causing danger.
Wait until the oil cools down.
Oil flows out Oil level is correct.
Oil does not flow out Oil level is low.
Add transmission
oil until oil flows
out.
9Inspect the gasket (oil check bolt), replace if
damaged.
9Tighten the oil check bolt.
Recommended oil:
Yamalube 4 (10W-30) or SAE
10W-30 type SE motor oil
Oil check bolt:
10 Nm (1.0 m•kg, 7.2 ft•lb)

3-15
INSP
ADJIDLE SPEED ADJUSTMENT/MUFFLER INSPECTION/
SILENCER FIBER REPLACEMENT
EC35M010
IDLE SPEED ADJUSTMENT
1. Start the engine and thoroughly warm it up.
2. Adjust:
9Idle speed
EC35P030
MUFFLER INSPECTION
1. Inspect:
9O-ring 1
Damage Replace.
NOTE:
Install the O-rings with their depressed afacing
outward.
EC35R050
SILENCER FIBER REPLACEMENT
1. Remove:
9Side cover (right)
9Bolt (silencer) 1
9Silencer 2
9Bolt (fiber) 3
Adjustment steps:
9Loosen the locknut 1.
9Turn the throttle stop screw 2until the en-
gine runs at the lowest possible speed.
9Tighten the locknut.
To increase idle speed Turn the throttle
stop screw 2 2
in.
To decrease idle speed Turn the throttle
stop screw 2 2
out.