engine YAMAHA YZ125LC 2007 Owner's Manual

1-16
GEN
INFO
TORQUE-CHECK POINTS
EC1A0013
TORQUE-CHECK POINTS
Frame construction Frame to rear frame
Combined seat and tank Fuel tank to frame
Engine mounting Frame to engine
Engine bracket to engine
Engine bracket to frame
Steering Steering shaft to Steering shaft to frame
handlebar Steering shaft to handle crown
Handle crown to handlebar
Suspension Front Steering shaft to Front fork to handle crown
front fork Front fork to under bracket
Rear For link type Assembly of links
Link to frame
Link to shock absorber
Link to swingarm
Rear Installation of shock Shock absorber to frame
absorber
Rear Installation of swingarm Tightening of pivot shaft
Wheel Installation of wheel Front Tightening of front axle
Tightening of axle holder
Rear Tightening of rear axle
Wheel to sprocket
Brake Front Caliper to front fork
Brake disc to wheel
Tightening of union bolt
Master cylinder to handlebar
Tightening of air bleeder
Tightening of brake hose holder
Rear Brake pedal to frame
Brake disc to wheel
Tighening of union bolt
Master cylinder to frame
Tightening of air bleeder
Tightening of brake hose holder
Fuel system Fuel tank to fuel cock
NOTE:
Concerning the tightening torque, refer to “
MAINTENANCE SPECIFICATIONS” section in
the CHAPTER 2.
1C3-9-32-1B 4/5/06 5:26 PM Page 10

1-17
GEN
INFO
CLEANING AND STORAGE
EC1B0000
CLEANING AND STORAGE
EC1B1000
CLEANING
Frequent cleaning of your machine will enhance
its appearance, maintain good overall perfor-
mance, and extend the life of many components.
1. Before washing the machine, block off the
end of the exhaust pipe to prevent water
from entering. A plastic bag secured with a
rubber band may be used for this purpose.
2. If the engine is excessively greasy, apply
some degreaser to it with a paint brush. Do
not apply degreaser to the chain, sprockets,
or wheel axles.
3. Rinse the dirt and degreaser off with a gar-
den hose; use only enough pressure to do
the job.
cC
Excessive hose pressure may cause water
seepage and contamination of wheel bear-
ings, front forks, brakes and transmission
seals. Many expensive repair bills have re-
sulted from improper high pressure deter-
gent applications such as those available
in coin-operated car washers.
4. After the majority of the dirt has been hosed
off, wash all surfaces with warm water and a
mild detergent. Use an old toothbrush to
clean hard-to-reach places.
5. Rinse the machine off immediately with
clean water, and dry all surfaces with a soft
towel or cloth.
6. Immediately after washing, remove excess
water from the chain with a paper towel and
lubricate the chain to prevent rust.
7. Clean the seat with a vinyl upholstery clean-
er to keep the cover pliable and glossy.
8. Automotive wax may be applied to all paint-
ed or chromed surfaces. Avoid combination
cleaner-waxes, as they may contain abra-
sives.
9. After completing the above, start the engine
and allow it to idle for several minutes.
1C3-9-32-1B 4/5/06 5:26 PM Page 14

1-18
GEN
INFO
CLEANING AND STORAGE
EC1B2001
STORAGE
If your machine is to be stored for 60 days or
more, some preventive measures must be taken
to avoid deterioration. After cleaning the ma-
chine thoroughly, prepare it for storage as fol-
lows:
1. Drain the fuel tank, fuel lines, and the carbu-
retor float bowl.
2. Remove the spark plug, pour a tablespoon
of SAE 10W-30 motor oil in the spark plug
hole, and reinstall the plug. With the engine
stop switch pushed in, kick the engine over
several times to coat the cylinder walls with
oil.
3. Remove the drive chain, clean it thoroughly
with solvent, and lubricate it. Reinstall the
chain or store it in a plastic bag tied to the
frame.
4. Lubricate all control cables.
5. Block the frame up to raise the wheels off
the ground.
6. Tie a plastic bag over the exhaust pipe out-
let to prevent moisture from entering.
7. If the machine is to be stored in a humid or
salt-air environment, coat all exposed metal
surfaces with a film of light oil. Do not apply
oil to rubber parts or the seat cover.
NOTE:
Make any necessary repairs before the machine
is stored.
1C3-9-32-1B 4/5/06 5:26 PM Page 16

2-1
SPECGENERAL SPECIFICATIONS
Model name: YZ125W1 (USA, CDN)
YZ125 (EUROPE, ZA)
YZ125W (AUS, NZ)
Model code number: 1C39 (USA, CDN)
1C3A (EUROPE)
1C3C (AUS, NZ, ZA)
Dimensions: USA, AUS, NZ, ZA EUROPE, CDN
Overall length 2,135 mm 2,139 mm
(84.1 in) (84.2 in)
Overall width 827 mm←
(32.6 in)
Overall height 1,315 mm 1,318 mm
(51.8 in) (51.9 in)
Seat height 997 mm 998 mm
(39.3 in) (39.3 in)
Wheelbase 1,443 mm←
(56.8 in)
Minimum ground clearance 386 mm 388 mm
(15.2 in) (15.3 in)
Dry weight:
Without oil and fuel 86.0 kg (189.6 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 8.6~10.7 : 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 0.66 L (0.58 Imp qt, 0.69 US qt)
Total amount 0.70 L (0.62 Imp qt, 0.74 US qt)
Coolant capacity (including all routes): 0.9 L (0.79 Imp qt, 0.95 US qt)
Air filter: Wet type element
Fuel:
Type Premium unleaded gasoline
only with a research octane
number of 95 or higher
Tank capacity 8.0 L (1.76 Imp gal, 2.11 US gal)
EC200000
SPECIFICATIONSEC211000
GENERAL SPECIFICATIONS
1C3-9-32-2A 4/29/06 10:17 AM Page 2

2-3
SPECMAINTENANCE SPECIFICATIONS
Item Standard Limit
Cylinder head:
Combustion chamber capacity 8.4 cm
3…
(0.296 Imp oz, 0.284 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 40.1 mm (1.579 in) 38.1 mm (1.500 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
1C3-9-32-2A 4/29/06 10:17 AM 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 10 1.0 7.2
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 19 1.9 13
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 70 7.0 50
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 2 0.2 1.4
Swingarm and patch M 4 ×0.7 4 2 0.2 1.4
Chain tensioner mounting M 8 ×1.25 2 16 1.6 11
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
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 4 0.4 2.9
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.


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1C3-9-32-2A 4/29/06 10:17 AM 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
1C3-9-32-2A 4/29/06 10:17 AM Page 13

2-13
SPECCABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1“ENGINE STOP” button lead
2Throttle cable
3Clutch cable
4Ground lead
5High tension cord
6Clamp
7Air vent hose
8Radiator breather hose
9CDI magneto lead
0YPVS breather hose
qEngine bracket (right)
wEngine bracket (left)
eCrankcase breather hose
rOverflow hose
tConnector coverAPass the clutch cable on the
outside of the throttle cable and
“ENGINE STOP” button lead.
BAlign the throttle cable locating
tape with the cable guide.
CPass the throttle cable, clutch
cable and “ENGINE STOP”
button lead above the radiator
hose.
DInstall the ignition coil, side
core and ground lead together
to the frame. Take care to fas-
ten the ground lead so that its
terminal is within the indicated
range.
EClamp the throttle cable and
high tension cord to the frame.FClamp the clutch cable to the
left engine bracket. Clamp the
clutch cable below the posi-
tioning grommet.
GPass the air vent hose back of
the throttle cable.
HPass the air vent hose, over-
flow hose and crankcase
breather hose between the
frame and connecting rod.
IPass 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.
1C3-9-32-2B 4/29/06 10:16 AM Page 26

2-13
SPEC
SCHEMA DE CHEMINEMENT DES CABLES
KABELFÜHRUNGSÜBERSICHTPLAN
DIAGRAMMA DEL PASSAGGIO DEI CAVI
KABELFÜHRUNGSÜBER-
SICHTPLAN
1„ENGINE STOP“-Schalterkabel
2Gaszug
3Kupplungszug
4Erdungskabel
5Hochspannungskabel
6Klemme
7Belüftungsschlauch
8Kühler-Entlüftungsschlauch
9CDI-Magnetkabel
0YPVS-Entlüftungsschlauch
qMotorhalterung (rechts)
wMotorhalterung (links)
eKurbelgehäuse-Entlüftungsschlauch
rÜberlaufschlauch
tSteckverbinder-Abdeckung
ADen Kupplungszug außen am Gaszug
und am „ENGINE STOP“-Schalterkabel
entlangführen.
BDas Gaszug-Lokalisierungsband an der
Kabelführung ausrichten.
CDen Gaszug, den Kupplungszug und
das „ENGINE STOP“-Schalterkabel
über dem Kühlerschlauch entlang-
führen.
DDie Zündspule, den Seitenkern und das
Erdungskabel zusammen am Rahmen
installieren. Darauf achten, dass das
Erdungskabel angeschlossen wird,
damit sich der Anschluss innerhalb des
angezeigten Bereichs befindet.
EDen Gaszug und das Hochspannungs-
kabel am Rahmen festklammern.
FDen Kupplungszug an der linken Motor-
halterung festklammern. Den Kupp-
lungszug unter der Positionierungsgum-
mitülle festklammern.
GDen Belüftungsschlauch an der Rück-
seite des Gaszugs entlangführen.
HDen Belüftungsschlauch, den Überlauf-
schlauch und den Kurbelgehäuse-Ent-
lüftungsschlauch zwischen dem Rah-
men und der Verbindungsstange ent-
langführen.
IDen Kühler-Entlüftungsschlauch und
den YVPS-Entlüftungsschlauch an der
Außenseite der Motorhalterung und der
Innenseite des Rahmenunterzuges ent-
langführen. Anschließend den Kühler-
Entlüftungsschlauch innerhalb des
YVPS-Entlüftungsschlauches entlang-
führen.
SCHEMA DE
CHEMINEMENT DES
CABLES
1Fil du bouton “ENGINE STOP”
2Câble des gaz
3Câble d’embrayage
4Fil de masse
5Fil haute tension
6Collier à pince
7Durit de ventilation
8Durit de mise à l’air du radiateur
9Fil de magnéto CDI
0Durit de mise à l’air YPVS
qSupport du moteur (droit)
wSupport du moteur (gauche)
eDurit de mise à l’air de carter
rDurit de trop-plein
tCapuchon de connecteur
åFaire passer le câble d’embrayage à
l’extérieur du câble des gaz et du fil du
bouton “ENGINE STOP”.
∫Aligner la bande de positionnement du
câble des gaz sur le guide du câble.
çFaire passer le câble des gaz, le câble
d’embrayage et le fil du bouton “ENGI-
NE STOP” au-dessus de la durit de mise
à l’air du radiateur.
∂Installer la bobine d’allumage, le fais-
ceau latéral et le fil de masse ensemble
sur le cadre. Fixer le fil de masse de
façon à ce que sa borne se trouve dans la
plage indiquée.
´Brider le câble des gaz et le fil haute ten-
sion au cadre.
ƒBrider le câble d’embrayage sur le sup-
port gauche du moteur. Brider le câble
d’embrayage sous l’œillet de positionne-
ment.
©Refaire passer la durit de ventilation du
câble des gaz.
˙Faire 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.
ˆFaire passer la durit de mise à l’air du
radiateur et la durit de mise à l’air YPVS
à l’extérieur du support du moteur et à
l’intérieur du tube inférieur. Ensuite,
faire passer la durit de mise à l’air du
radiateur à l’intérieur de la durit de mise
à l’air YPVS.
IC240000
DIAGRAMMA DEL
PASSAGGIO DEI CAVI
1Conduttore del pulsante “ARRESTO
MOTORE”
2Cavo acceleratore
3Cavo frizione
4Conduttore di terra
5Cavo alta tensione
6Morsetto
7Flessibile di sfiato aria
8Flessibile di sfiato aria del radiatore
9Cavo magnete CDI
0Flessibile di sfiato YPVS
qStaffa motore (destra)
wStaffa motore (sinistra)
eTubo di sfiato del carter
rFlessibile di troppopieno carburante
tCoperchio del connettore
åFar passare il cavo della frizione dal lato
esterno del cavo dell’acceleratore e del
conduttore del pulsante “ARRESTO
MOTORE”.
∫Allineare il nastro di posizione del cavo
acceleratore con la guida per cavi.
çFar passare il cavo dell’acceleratore, il
cavo della frizione e il conduttore del
pulsante “ARRESTO MOTORE” sopra
il flessibile entrata radiatore.
∂Installare insieme nel telaio la bobina di
accensione, il nucleo laterale e il condut-
tore di terra. Il conduttore di terra deve
essere agganciato in modo tale che il suo
terminale rientri nella gamma indicata.
´Agganciare al telaio il cavo acceleratore
e il cavo alta tensione.
ƒAgganciare 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 dietro al
cavo acceleratore.
˙Far passare il flessibile di sfiato aria, il
flessibile di troppopieno carburante e il
flessibile di sfiato del carter tra il telaio e
la biella.
ˆPassare il flessibile di sfiato aria e il fles-
sibile di sfiato YPVS all’esterno della
staffa del motore e dentro il tubo discen-
dente. Quindi passare il flessibile di sfia-
to aria del radiatore dentro il flessibile di
sfiato YPVS.
1C3-9-32-2B 4/29/06 10:16 AM Page 27

2-15
SPECCABLE ROUTING DIAGRAM
1High tension cord
2“ENGINE STOP” button lead
3Ignition coil lead
4Clamp
5CDI unit
6CDI unit band
7Radiator breather hose
8CDI magneto lead
9Connector cover
0Throttle cable
qClutch cable
wCDI unit stay
APass the high tension cord to
the left of the radiator hose.
BUsing a plastic locking tie,
clamp the “ENGINE STOP”
button lead, ignition coil leadand CDI magneto lead togeth-
er with the clamp ends back-
ward and then cut off the tie
end.
CClamp to the frame the throttle
cable, clutch cable, ignition coil
lead and “ENGINE STOP” but-
ton lead. In so doing, clamp
the ignition coil lead and
“ENGINE STOP” button lead at
their protecting tubes. Tighten
the clamp so that the “ENGINE
STOP” button lead is not
pulled when the handlebar is
turned to the right and left.
DPass the CDI magneto lead
and radiator breather hose
between the frame and the
radiator(right).EClamp the CDI magneto lead
to the frame at its locating
tape.
FBring the connector cover into
contact with the coupler.
GLocate the clamp ends in the
arrowed range.
HInsert the CDI unit band until it
stops at the CDI unit stay.
IPass the CDI magneto lead
and radiator breather hose
between the frame and the
radiator hose so that they
come within the arrow-indicat-
ed range. Also take care so
that the CDI magneto lead
passes on the left of the radia-
tor breather hose.
1C3-9-32-2B 4/29/06 10:16 AM Page 30