2002 YAMAHA YZ125LC engine

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 TMXχ
38SS←
/MIKUNI
I.D. mark 5NY1 00 5NY2 10…
Main jet (M.J.) #420 #430…
Jet needle-clip position (J.N.) 6CHY5-79-3 6CHY5-77-3…
Cutaway (C.A.) 5.75←…
Pilot jet (P.J.) #30←…
Pilot air screw (P.A.S.) 2-1/2 1-3/4…
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 11.5~12.5 mm
(0.37~0.41 in) (0.45~0.49 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 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) 0.57 L (0.50 Imp qt, 0.60 US qt)…
Water pump:
Type Single-suction centrifugal pump…
5NY-9-30-2A 5/24/01 8:03 PM Page 5

2-10
SPECMAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q'tyT ightening torqueNm m•kg ft•lb
Rear brake master cylinder and frame M 6 ×1.0 2 10 1.0 7.2
Rear brake reservoir tank and frame M 6 ×1.0 1 7 0.7 5.1
Rear brake hose union bolt (caliper) M10 ×1.25 1 30 3.0 22
Rear brake hose union bolt (master cylinder) M10 ×1.25 1 30 3.0 22
Rear wheel axle and nut M20 ×1.5 1 125 12.5 90
Nipple (spoke) – 72 3 0.3 2.2
Driven sprocket and wheel hub M 8 ×1.25 6 42 4.2 30
Disc cover and rear brake caliper M 6 ×1.0 2 7 0.7 5.1
Protector and rear brake caliper M 6 ×1.0 2 7 0.7 5.1
Engine mounting:
Engine and frame (front) M10 ×1.25 1 69 6.9 50
Engine and frame (lower) M10 ×1.25 1 69 6.9 50
Engine bracket and frame M 8 ×1.25 2 34 3.4 24
Engine bracket and engine M 8 ×1.25 1 34 3.4 24
Pivot shaft and nut M16 ×1.5 1 85 8.5 61
Relay arm and swingarm M14 ×1.5 1 80 8.0 58
Relay arm and connecting rod M14 ×1.5 1 80 8.0 58
Connecting rod and frame M14 ×1.5 1 80 8.0 58
Rear shock absorber and frame M10 ×1.25 1 56 5.6 40
Rear shock absorber and relay arm M10 ×1.25 1 53 5.3 38
Rear frame and frame M 8 ×1.25 3 29 2.9 21
Swingarm and brake hose holder M 5 ×0.8 4 2 0.2 1.4
Chain tensioner mounting M 8 ×1.25 2 19 1.9 13
Chain support and swingarm M 6 ×1.0 3 7 0.7 5.1
Seal guard and swingarm M 5 ×0.8 4 6 0.6 4.3
Fuel tank mounting M 6 ×1.0 2 10 1.0 7.2
Fuel tank and fuel cock M 6 ×1.0 2 7 0.7 5.1
Fuel tank and seat set bracket M 6 ×1.0 1 7 0.7 5.1
Fuel tank and hooking screw (fitting band) M 6 ×1.0 1 7 0.7 5.1
Fuel tank and fuel tank bracket M 6 ×1.0 4 7 0.7 5.1
Air scoop mounting M 6 ×1.0 6 4 0.4 2.9
Front fender mounting M 6 ×1.0 4 7 0.7 5.1
Rear fender mounting M 6 ×1.0 4 7 0.7 5.1
Side cover mounting M 6 ×1.0 2 7 0.7 5.1
Seat mounting M 8 ×1.25 2 19 1.9 13
Number plate M 6 ×1.0 1 7 0.7 5.1
NOTE:

- marked portion shall be checked for torque tightening after break-in or before each race.


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5NY-9-30-2A 5/24/01 8:03 PM Page 11

2-12
SPEC
GENERAL TORQUE SPECIFICATIONS/
DEFINITION OF UNITS
This chart specifies torque for standard faste-
ners with standard I.S.O. pitch threads. Torque
specifications for special components or assem-
blies are included in the applicable sections of
this book. To avoid warpage, tighten multi-faste-
ner assemblies in a crisscross fashion, in pro-
gressive stages, until full torque is reached.
Unless otherwise specified, torque specifications
call for clean, dry threads. Components should
be at room temperature.
A: Distance across flats
B: Outside thread diameter
EC230000
DEFINITION OF UNITS
EC220001
GENERAL TORQUE SPECIFICATIONS
A B TORQUE SPECIFICATION
(Nut) (Bolt)
Nm m•kg ft•lb
10 mm 6 mm 6 0.6 4.3
12 mm 8 mm 15 1.5 11
14 mm 10 mm 30 3.0 22
17 mm 12 mm 55 5.5 40
19 mm 14 mm 85 8.5 61
22 mm 16 mm 130 13 94
Unit Read Definition Measure
mm milimeter 10-
3meter Length
cm centimeter 10-2meter Length
kg kilogram 103gram Weight
N Newton 1 kg ×m/sec2Force
Nm Newton meter N ×m Torque
m•kg Meter kilogrma m ×kg Torque
Pa Pascal N/m2Pressure
N/mm Newton per millimeter N/mm Spring rate
L Liter — Volume or capacity
cm3Cubic centimeter — Volume or capacity
r/min Revolution per minute — Engine speed
5NY-9-30-2A 5/24/01 8:03 PM Page 13

2-13
SPECCABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1Brake hose
2Cable guide
3“ENGINE STOP” button lead
4Fuel tank breather hose
5Clamp
6Throttle cable
7Air vent hose (right)
8Air vent hose (left)
9Transmission oil breather hose
0Overflow hose
qYPVS breather hose
wRadiator breather hose
eCDI magneto lead
rWireharnessAPass the throttle cable and
“ENGINE STOP” button lead
into the cable guide. Align
with the cable guide the
front end of the tape on the
throttle cable.
BPass the fuel tank breather
hose between the handlebar
and tension bar, then insert
its end into the hole of the
number plate.
CPass the throttle cable and
“ENGINE STOP” button lead
over the radiator hose.
DClamp the throttle cable,
“ENGINE STOP” button lead
and wireharness to the main
pipe. With the clamp ends
downward, tighten the throttle
cable to the extent that it
moves smoothly.
EClamp the “ENGINE STOP”
button lead (where there is no
protector), wireharness and
throttle cable all together to the
main pipe with the clamp ends
downward.FClamp the CDI magneto lead
on the upper part of
the frame gusset at its
protecting tube.
GClamp the throttle cable and
wireharness to the main pipe.
With the clamp ends downward,
tighten the throttle cable to the
extent that it moves smoothly.
HPass the air vent hose at
the rear of the throttle cable.
IPass the transmission oil
breather hose, air vent hoses
and overflow hose between
the frame and connecting rod.
JPass the radiator breather
hose and YPVS breather hose
outside the engine bracket
and inside the down tube. Then
pass the radiator breather
hose inside the YPVS
breather hose.
KClamp the radiator breather
hose and CDI magneto lead
on the rear of the down-tube.
5NY-9-30-2B 5/23/01 8:03 PM Page 26

2-13
SPEC
SCHEMA DE CHEMINEMENT DES CABLES
KABELFÜHRUNGSÜBERSICHTPLAN
DIAGRAMMA DEL PASSAGGIO DEI CAVI
KABELFÜHRUNGSÜBER-
SICHTPLAN
1Bremsschlauch
2Kabelführung
3Leitungskabel des Motorstoppknopfes
„ENGINE STOP“
4Kraftstofftank-Belüftungsschlauch
5Klemme
6Gasseil
7Belüftungsschlauch (Rechts)
8Belüftungsschlauch (Links)
9Getriebeöl-Belüftungsschlauch
0Überlaufschlauch
qYPVS-Belüftungsschlauch
wKühler-Belüftungsschlauch
eLeitungskabel des CDI-Magnetzünders
rKabelbaum
ADas Gasseil und den Leitungsdraht der
„ENGINE STOP“-Taste durch die
Kabelführing führen.
Vorderes Bandende am Gaskabel mit
der Kabelführung ausrichten.
BDen Kraftstofftank-Belüftungsschlauch
zwischen der Lenkstange und der Zug-
stange durchführen und danach sein
Ende in die Bohrung des Nummern-
schildes einsatzen.
CDas Gasseil und das Leitungskabel des
Motorstoppknopfes „ENGINE STOP“
über dem Kühlerschlauch durchführen.
DGaskabel, Motorstoppknopf „ENGINE
STOP“ und Kabelbaum am Hauptrohr
festklemmen. Mit den Schellenenden
nach unten zieht man das Gaskabelen-
de so fest, dass es sich reibungslos
bewegt.
ELeitung des Motorstoppknopfes „ENGI-
NE STOP“ (wenn kein Schutz vorhan-
den ist), Kabelbaum und Gaskabel
gemeinsam am Hauptrohr festklem-
men, mit den Schellenenden nach
unten.
FDas Leitengskabel des CDI-Magnetzün-
ders am oberen Teil der Rehmensfütze
an ihrem Schutzrohr festklemmen.
GGaskabel und Kabelbaum am Haupt-
rohr festklemmen. Mit den Enden der
Schelle nach unten zeigend, zieht man
das Gaskabel so fest, dass es sich rei-
bungslos bewegt.
HDen Belüftungsschlauch hinter dem
Gasseil durchführen.
IDen Getriebeöl-Belüftungsschlauch, die
Belüftungsschläuche und den Üderlauf-
schlauch zwischen dem Rahmen und
der Verbindungsstange durchführen.
JKühlerbelüftungsschlauch und YPVS-
Belüftungsschlauch an der Aussenseite
der Motorhalterung und an den Innen-
seite des Abwärtsrohrs führen. Dann
Kühlerbelüftungsschlauch in den YPVS-
Belüftungsschlauch einführen.
KDen Kühler-Belüftungsschlauch und
das Leitungskabel des CDI-Magnetzün-
ders an der Rückseite des Fallrohres
festklemmen.
SCHEMA DE
CHEMINEMENT DES
CABLES
1Tuyau de frein
2Guide de câble
3Fil de bouton d’arrêt du moteur “ENGINE
STOP”
4Tuyau de reniflard de réservoir à essence
5Bride
6Câble d’accélérateur
7Tuyau de ventilation (droit)
8Tuyau de ventilation (gauche)
9Tuyau de reniflard d’huile de boîte de
vitesses
0Tube de trop-plein
qTube de reniflard YPVS
wTuyau de reniflard de radiateur
eFil de magnéto CDI
rFaisceau de fils
åFaire passer le câble d’accélérateur et le fil
du bouton “ENGINE STOP” (arrêt
moteur) dans le guidage de câble.
Aligner sur le guide-câble l’extrémité
avant du ruban du câble d’accélérateur.
∫Faire passer le tuyau de reniflard du réser-
voir à carburant entre le guidon et la barre
de tension, puis l’insérer dans l’orifice de
la plaque minéralogique.
çFaire passer le câble d’accélérateur et le fil
du bouton d’arrêt moteur “ENGINE
STOP” au-dessus de la durit de radiateur.
∂Fixez le câble d’accélérateur, le fil du
bouton “ENGINE STOP” et le faisceau
de fils sur le tube principal. Les extrémi-
tés de la bride étant orientées vers le bas,
serrez le câble d’accélérateur de manière
à ce qu’il se déplace aisément.
´Fixez le fil du bouton “ENGINE STOP”,
le faisceau de fils et le câbled’accéléra-
teur ensemble sur le tube principal avec
les extrémités de la bride orientées vers
le bas.
ƒFixer le fil de magnéto de CDI sur la partie
supérieure du couvre-joint du tube de pro-
tection.
©Bridez le câble d’accélérateur et le fais-
ceau de fils sur le tube principal. En
orientant les extrémités de la bride vers
le bas, serrez le câble d’accélérateur de
façon à ce qu’il bouge facilement.
˙Faire passer le tuyau de ventilation à
l’arrière du câble d’accélérateur.
ˆFaire passer le tube reniflard d’huile de
transmission, les tubes d’aération et le tube
de trop-plein.
∆Faites passer le tuyau du reniflard du
radiateur et le tuyau du reniflard de
l’YPVS à l’extérieur du support du
moteur et à l’intérieur du tube inférieur.
Faites ensuite passer le tuyau du reniflard
du radiateur à l’intérieur tuyau du reni-
flard de l’YPVS.
˚Fixer avec un collier le tuyau de reniflard
du radiateur et le fil de magnéto CDI.
IC240000
DIAGRAMMA DEL
PASSAGGIO DEI CAVI
1Tubo flessibile del freno
2Guida per cavi
3Conduttore del pulsante “ARRESTO
MOTORE”
4Sfiato del serbatoio del carburante
5Brida
6Cavo dell’acceleratore
7Tubo flessibile dello sfiatatoio dell’aria
(destro)
8Tubo flessibile dello sfiatatoio dell’aria
(sinistro)
9Sfiato dell’olio per trasmissioni
0Tubo flessibile di troppopieno
qSfiato YPVS
wSfiato del radiatore
eConduttore del magneto CDI
rComplesso conduttori
åFar passare il cavo dell’acceleratore e il
conduttore del pulsante “ARRESTO
MOTORE” nella guida per cavi.
Allineare con la guida per cavi l’estre-
mità anteriore del nastro sul cavo dell'ac-
celeratore.
∫Far passare lo sfiato del serbatoio puran-
te fra il manubrio e il tirante, quindi inse-
rirne l’estremità nel foro della targa.
çFar passare il cavo dell’acceleratore e il
conduttore del pulsante “ARRESTO
MOTORE” sopra il manicotto flessibile
del radiatore.
∂Assicurare al tubo principale il cavo
dell’acceleratore e il conduttore e il
cablaggio preassemblato del pulsante
“ARRESTO MOTORE”. Con le estre-
mità della brida verso il basso, assicurare
il cavo dell’acceleratore in modo che
possa scorrere facilmente.
´Assicurare tutti insieme al tubo principa-
le, con le estremità della brida verso il
basso, il conduttore del pulsante “ARRE-
STO MOTORE” (dove non vi è prote-
zione), il cablaggio preassemblato e il
cavo dell’acceleratore.
ƒBloccare il conduttore del magnete CDI
sulla parte superiore del fazzoletto del
telaio in corrispondeza del suo tubo di
protezione.
©Assicurare al tubo principale il cavo del-
l'acceleratore e il cablaggio preassembla-
to. Con le estremità della brida rivolte
verso il basso, assicurare il cavo dell'ac-
celeratore in modo che possa scorrere
facilmente.
˙Far passare il tubo flessibile dello sfiata-
toio dell’aria sul retro del cavo dell’acce-
leratore.
ˆFar passare lo sfiato dell’olio per tra-
smissioni, i tubi flessibili degli sfiatatoi
dell’aria e il tubo flessibile di troppopie-
no fra il telaio e la leva di rinvio.
∆Far passare lo sfiato del radiatore e lo
sfiato YPVS fuori dalla staffa del motore
dentro il tubo inferiore. Quindi far passa-
re lo sfiato del radiatore dentro lo sfiato
dell’YPVS.
˚Bloccare lo sfiato del radiatore e il con-
duttore del magnete CDI sul retro del
tubo rivolto verso il basso.
5NY-9-30-2B 5/23/01 8:03 PM Page 27

2-17
SPECCABLE ROUTING DIAGRAM
AInstall the brake hose so that its pipe portion
directs as show and lightly touches the
projection on the master cylinder.
BPass the “ENGINE STOP” button lead in
the middle of the clutch holder.
CPass the clutch cable in front of the throttle
cable.
DClamp the “ENGINE STOP” button lead to
the handlebar to 3 clicks.
EPass the brake hose in front of the number
plate and through the cable guide.
FCross the clutch cable and throttle cable
over the number plate boss. 1Brake hose
2Master cylinder
3“ENGINE STOP” button lead
4“ENGINE STOP” button
5Throttle cable
6Clutch cable
7Clamp
8Cable guide
5NY-9-30-2B 5/23/01 8:03 PM Page 34

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.
5NY-9-30-2B 5/23/01 8:03 PM Page 35

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
P7-1~24
results of test runs before racing? Are inspection and
maintenance completely done?
5NY-9-30-3A 5/23/01 8:24 PM Page 14