2005 YAMAHA YZ125LC engine

2-3
SPECMAINTENANCE SPECIFICATIONS
Item Standard Limit
Cylinder head:
Combustion chamber capacity 8.5 cm
3…
(0.299 Imp oz, 0.287 US oz)
Warp limit…
0.03 mm (0.0012 in)
Cylinder:
Bore size 54.000~54.014 mm 54.1 mm (2.130 in)
(2.1260~2.1265 in)
Taper limit…
0.05 mm (0.0020 in)
Out of round limit…
0.01 mm (0.0004 in)
Piston:
Piston size/ 53.957~53.972 mm…
(2.1243~2.1249 in)
Measuring point* 17.5 mm (0.69 in)…
Piston clearance 0.040~0.045 mm 0.1 mm (0.004 in)
(0.0016~0.0018 in)
Piston offset 0.5 mm (0.019 in)/EX-side…
Piston pin:
Piston pin outside diameter 14.995~15.000 mm 14.975 mm
(0.5904~0.5906 in) (0.5896 in)
Piston ring:
Sectional sketch Plain…
B=1.0 mm (0.039 in)…
T=2.35 mm (0.093 in)…
End gap (installed) 0.5~0.7 mm (0.020~0.028 in) 1.2 mm (0.047 in)
Side clearance (installed) 0.035~0.070 mm 0.1 mm (0.004 in)
(0.0014~0.0028 in)
Crankshaft:
Crank width “A” 55.90~55.95 mm …
(2.201~2.203 in)
Runout limit “C” 0.03 mm (0.0012 in) 0.05 mm (0.0020 in)
Connecting rod big end
side clearance “D” 0.06~0.64 mm (0.002~0.025 in)…
Small end free play “F” 0.8~1.0 mm (0.031~0.039 in) 2.0 mm (0.08 in)
Clutch:
Friction plate thickness 2.9~3.1 mm (0.114~0.122 in) 2.8 mm (0.110 in)
Quantity 8 …
Clutch plate thickness 1.5~1.7 mm (0.059~0.067 in) …
Quantity 7 …
Warp limit … 0.2 mm (0.008 in)
Clutch spring free length 41.2 mm (1.622 in) 39.2 mm (1.543 in)
Quantity 5 …
Clutch housing thrust clearance 0.15~0.26 mm (0.006~0.010 in) …
Clutch housing radial clearance 0.014~0.046 mm …
(0.0006~0.0018 in)
Clutch release method Inner push, cam push …
EC212000
MAINTENANCE SPECIFICATIONSEC212100
ENGINE
1C3-9-30-2A 25/5/04 7:13 PM Page 4

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 master cylinder cap M 4 ×0.7 2 2 0.2 1.4
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
Chain puller adjust bolt and locknut M 8 ×1.25 2 16 1.6 11
Engine mounting:
Engine and frame (front) M10 ×1.25 1 64 6.4 46
Engine and frame (lower) M10 ×1.25 1 64 6.4 46
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 (upper) M 8 ×1.25 1 32 3.2 23
Rear frame and frame (lower) M 8 ×1.25 2 29 2.9 21
Swingarm and brake hose holder M 5 ×0.8 4 1 0.1 0.7
Swingarm and patch M 4 ×0.7 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 5 0.5 3.6
Cable guide and frame M 5 ×0.8 2 4 0.4 2.9
Fuel tank mounting boss and frame M10 ×1.25 2 20 2.0 14
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 and fuel tank M 6 ×1.0 4 7 0.7 5.1
Air scoop and panel M 6 ×1.0 2 6 0.6 4.3
Front fender mounting M 6 ×1.0 4 7 0.7 5.1
Rear fender mounting (front) M 6 ×1.0 2 7 0.7 5.1
Rear fender mounting (rear) M 6 ×1.0 2 12 1.2 8.7
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.


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1C3-9-30-2A 25/5/04 7:13 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
1C3-9-30-2A 25/5/04 7:13 PM Page 13

2-13
SPECCABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1Ground lead
2High tension cord
3Grommet
4Air vent hose
5Crankcase breather hose
6Y.P.V.S. breather hose
7Throttle cable
8Clutch cable
9Engine bracket (right)
0Engine bracket (left)
qAir vent hose (left)
wAir vent hose (right)
e“ENGINE STOP” button leadAPass the clutch cable on the
outside of the throttle cable and
“ENGINE STOP” button lead.
BInsert the tip of the fuel tank
breather hose into the hole in
the steering shaft cap.
CAlign the throttle cable locating
tape with the cable guide.
DPass through the cable guide
the throttle cable, “ENGINE
STOP” button lead and clutch
cable.
EPass the throttle cable and
clutch cable above the radiator
hose, and pass the “ENGINE
STOP” button lead below the
radiator hose.FInstall the ignition coil, side
core and ground lead together
to the frame.
GClamp the clutch cable to the
left engine bracket. Clamp the
clutch cable below the position-
ing grommet.
HPass the air vent hose back of
the throttle cable.
IPass the air vent hose, over-
flow hose and crankcase
breather hose between the
frame and connecting rod.
1C3-9-30-2B 27/5/04 4:18 PM Page 26

2-13
SPEC
SCHEMA DE CHEMINEMENT DES CABLES
KABELFÜHRUNGSÜBERSICHTPLAN
DIAGRAMMA DEL PASSAGGIO DEI CAVI
KABELFÜHRUNGSÜBER-
SICHTPLAN
1Erdungskabel
2Hochspannungskabel
3Gummitülle
4Belüftungsschlauch
5Kurbelgehäuse-Entlüftungsschlauch
6Y.P.V.S.-Entlüftungsschlauch
7Gaszug
8Kupplungszug
9Motorhalterung (rechts)
0Motorhalterung (links)
qBelüftungsschlauch (links)
wBelüftungsschlauch (rechts)
e„ENGINE STOP“-Schalterkabel
ADen Kupplungszug außen am Gaszug
und am „ENGINE STOP“-Schalterkabel
entlangführen.
BDie Spitze des Kraftstofftank-Belüf-
tungsschlauches in die Öffnung des
Lenkwellendeckels einsetzen.
CDas Gaszug-Lokalisierungsband an der
Kabelführung ausrichten.
DDen Gaszug, das „ENGINE STOP“-
Schalterkabel und den Kupplungszug
durch die Kabelführung führen.
EDen Gaszug und den Kupplungszug
über dem Kühlerschlauch entlang-
führen, und das „ENGINE STOP“-
Schalterkabel unter dem Kühler-
schlauch entlangführen.
FDie Zündspule, den Seitenkern und das
Erdungskabel zusammen am Rahmen
installieren.
GDen Kupplungszug an der linken Motor-
halterung festklammern. Den Kupp-
lungszug unter der Positionierungsgum-
mitülle festklammern.
HDen Belüftungsschlauch an der Rück-
seite des Gaszugs entlangführen.
IDen Belüftungsschlauch, den Überlauf-
schlauch und den Kurbelgehäuse-Ent-
lüftungsschlauch zwischen dem Rah-
men und der Verbindungsstange ent-
langführen.
SCHEMA DE
CHEMINEMENT DES
CABLES
1Fil de masse
2Câble haute tension
3Œillet en caoutchouc
4Durit de ventilation
5Durit de mise à l’air du carter moteur
6Durit de mise à l’air Y.P.V.S.
7Câble des gaz.
8Câble d'embrayage
9Support du moteur (droit)
0Support du moteur (gauche)
qDurit de ventilation (gauche)
wDurit de ventilation (droite)
eFil du bouton “ENGINE STOP”
åFaire passer le câble d’embrayage à
l’extérieur du câble des gaz et du fil du
bouton “ENGINE STOP”.
∫Insérer l’extrémité de la durit de mise à
l’air du réservoir de carburant dans l’ori-
fice du bouchon d’axe de direction.
çAligner la bande de positionnement du
câble des gaz sur le guide du câble.
∂Faire passer dans guide de câble le câble
des gaz, le fil du bouton “ENGINE
STOP” et le câble d’embrayage.
´Faire passer le câble des gaz et le câble
d’embrayage au-dessus de la durit du
radiateur, et faire passer le fil du bouton
“ENGINE STOP” sous la durit du radia-
teur.
ƒInstaller la bobine d’allumage, le fais-
ceau latéral et le fil de masse ensemble
sur le cadre.
©Brider le câble d’embrayage sur le sup-
port gauche du moteur. Brider le câble
d’embrayage sous l’œillet en caoutchouc
de positionnement.
˙Refaire passer la durit de ventilation
depuis le câble des gaz.
ˆFaire passer la durit de ventilation, la
durit de trop-plein et la durit de mise à
l’air du carter moteur entre le cadre et la
bielle.
IC240000
DIAGRAMMA DEL
PASSAGGIO DEI CAVI
1Conduttore di terra
2Cavo alta tensione
3Boccola isolante
4Flessibile di sfiato aria
5Tubo di sfiato del carter
6Tubo di sfiato Y.P.V.S.
7Cavo acceleratore
8Cavo frizione
9Staffa motore (destra)
0Staffa motore (sinistra)
qFlessibile di sfiato aria (sinistro)
wFlessibile di sfiato aria (destro)
eConduttore del pulsante “ARRESTO
MOTORE”
åFar passare il cavo della frizione dal lato
esterno del cavo dell’acceleratore e del
conduttore del pulsante “ARRESTO
MOTORE”.
∫Inserire la punta del flessibile di sfiato
del serbatoio carburante nel foro del
coperchio dell’albero dello sterzo.
çAllineare il nastro di posizione del cavo
acceleratore con la guida per cavi.
∂Far passare attraverso la guida per cavi il
cavo acceleratore, il conduttore del pul-
sante “ARRESTO MOTORE” e il cavo
frizione.
´Far passare il cavo acceleratore e il cavo
frizione sopra il flessibile radiatore, e far
passare il conduttore del pulsante
“ARRESTO MOTORE” sotto il flessibi-
le del radiatore.
ƒInstallare la bobina di accensione, il
nucleo laterale e il conduttore di terra
insieme nel telaio.
©Agganciare il cavo frizione alla staffa
sinistra del motore. Agganciare il cavo
frizione sotto la boccola isolante di posi-
zionamento.
˙Passare il flessibile di sfiato aria al dorso
del cavo acceleratore.
ˆFar passare il flessibile di sfiato aria, il
flessibile di troppopieno carburante e il
flessibile di sfiato del carter tra il telaio e
la biella.
1C3-9-30-2B 27/5/04 4:18 PM Page 27

2-14
SPECCABLE ROUTING DIAGRAM
JPass the radiator breather hose
and Y.P.V.S. breather hose
from the outside of the engine
bracket to the inside of the
downtube.
KClamp the C.D.I. magneto lead,
radiator breather hose and
Y.P.V.S. breather hose.
LClamp to the frame the C.D.I.
magneto lead and radiator
breather hose.
MPass the air vent hose, over-
flow hose and crankcase
breather hose so that they do
not contact the rear shock
absorber.
1C3-9-30-2B 27/5/04 4:18 PM Page 28

2-15
SPECCABLE ROUTING DIAGRAM
1“ENGINE STOP” button lead
2C.D.I. magneto lead
3Ignition coil lead
4Ground lead
5Positioning tape
6Protection tube
7C.D.I.unit
8Throttle cable
9Clutch cable
0Side core
qRadiator breather hoseAPass the high tension cord to
the left of the radiator hose.
BClamp to the frame the
“ENGINE STOP” button lead
and C.D.I. magneto lead.
Clamp them in front of the radi-
ator fitting boss.
CClamp to the frame the throttle
cable, clutch cable and ignition
coil lead.
DPass the C.D.I. magneto lead
and radiator breather hose
between the frame and the
right side of the radiator.
EInsert the C.D.I. unit band until
it stops at the C.D.I. unit stay.
FPass the C.D.I. magneto lead
and radiator breather hose
between the frame and the
radiator hose.GLocate the clamp ends in the
arrowed range.
1C3-9-30-2B 16/6/04 9:51 AM Page 30

2-15
SPEC
SCHEMA DE CHEMINEMENT DES CABLES
KABELFÜHRUNGSÜBERSICHTPLAN
DIAGRAMMA DEL PASSAGGIO DEI CAVI
1„ENGINE STOP“-Schalterkabel
2CDI-Schwunglichtmagnetzünderkabel
3Zündspulenkabel
4Erdungskabel
5Positionierungsband
6Schutzschlauch
7CDI-Zündbox
8Gaszug
9Kupplungszug
0Seitenkern
qKühler-Entlüftungsschlauch
ADas Hochspannungskabel links am
Kühlerschlauch vorbeiführen.
BDas „ENGINE STOP“-Schalterkabel
und das CDI-Schwunglichtmagnetzün-
derkabel am Rahmen festklammern.
Beide vor der Kühler-Einbaunabe fest-
klammern.
CDen Gaszug, den Kupplungszug und
das Zündspulenkabel am Rahmen fest-
klammern.
DDas CDI-Schwunglichtmagnetzünder-
kabel und den Kühler-Entlüftungs-
schlauch zwischen dem Rahmen und
der rechten Seite des Kühlers entlang-
führen.
EDas CDI-Zündboxband einschieben, bis
es an der CDI-Zündboxhalterung
stoppt.
FDas CDI-Schwunglichtmagnetzünder-
kabel und den Kühler-Entlüftungs-
schlauch zwischen dem Rahmen und
dem Kühler-Entlüftungsschlauch ent-
langführen.
GDie Klemmenenden im zulässigen
Bereich anbringen.1Fil du bouton “ENGINE STOP”
2Fil du volant magnétique C.D.I.
3Fil de la bobine d’allumage
4Fil de masse
5Bande adhésive de positionnement
6Tube de protection
7Boîtier C.D.I.
8Câble des gaz.
9Câble d'embrayage
0Faisceau latéral
qDurit de mise à l’air du radiateur
åFaire passer le câble haute tension à
gauche de la durit de mise à l’air du
radiateur.
∫Brider au cadre le fil du bouton “ENGI-
NE STOP” et le fil du volant magnétique
C.D.I. Brider ces fils devant le bossage
de montage du radiateur.
çBrider au cadre le câble des gaz, le câble
d’embrayage et le fil de la bobine d’allu-
mage.
∂Faire passer le fil du volant magnétique
C.D.I. et la durit de mise à l’air du radia-
teur entre le cadre et le côté droit du
radiateur.
´Insérer la bande du boîtier C.D.I. jusqu’à
ce qu’il s’arrête contre le support du boî-
tier C.D.I.
ƒFaire passer le fil du volant magnétique
C.D.I. et la durit de mise à l’air du radia-
teur entre le cadre et la durit de mise à
l’air du radiateur.
GPlacer les extrémités du collier dans le
sens de la flèche.1Conduttore del pulsante “ARRESTO
MOTORE”
2Conduttore magnete C.D.I.
3Conduttore bobina d’accensione
4Conduttore di terra
5Nastro di posizionamento
6Tubo di protezione
7Unità CDI
8Cavo acceleratore
9Cavo frizione
0Nucleo laterale
qFlessibile di sfiato aria del radiatore
åPassare il cavo alta tensione a sinistra del
flessibile del radiatore.
∫Agganciare al telaio il conduttore pulsan-
te “ARRESTO MOTORE” e il condutto-
re magnete CDI. Agganciarli davanti alla
sporgenza del radiatore.
çAgganciare al telaio il cavo acceleratore,
il cavo frizione e il conduttore bobina
d’accensione.
∂Passare il conduttore magnete CDI e il
flessibile di sfiato aria del radiatore tra il
telaio e il lato destro del radiatore.
´Inserire nel sostegno dell’unità CDI il
nastro dell’unità CDI, finché non si
arresta.
ƒPassare il conduttore magnete CDI e il
flessibile di sfiato aria del radiatore tra il
telaio e flessibile di sfiato aria del radia-
tore.
GCollocare le estremità del morsetto entro
la gamma indicata dalle frecce.
1C3-9-30-2B 16/6/04 9:51 AM Page 31