2001 YAMAHA YZ250LC engine

2-3
MAINTENANCE SPECIFICATIONSSPEC
Item Standard Limit
Cylinder head:
Combustion chamber capacity 21.5 cm
3…
(0.757 Imp oz, 0.727 US oz)
Warp limit…
0.03 mm (0.0012 in)
Cylinder:
Bore size 66.400~66.414 mm 66.5 mm (2.618 in)
(2.6142~2.6147 in)
Taper limit…
0.05 mm (0.0020 in)
Out of round limit…
0.01 mm (0.0004 in)
Piston:
Piston size/ 66.352~66.367 mm…
(2.6120~2.6129 in)
Measuring point* 17.5 mm (0.69 in)…
Piston clearance 0.045~0.050 mm 0.1 mm (0.004 in)
(0.0018~0.0020 in)
Piston offset 1.5 mm (0.059 in)/EX-side…
Piston pin:
Piston pin outside diameter 17.995~18.000 mm 17.975 mm
(0.7085~0.7087 in) (0.7077 in)
Piston ring:
Sectional sketch Plain…
B=1.0 mm (0.039 in)…
T=2.55 mm (0.100 in)…
End gap (installed) 0.40~0.55 mm (0.016~0.022 in) 0.95 mm (0.037 in)
Side clearance (installed) : 1st
0.030~0.065 mm (0.0012~0.0026 in)0.1 mm (0.004 in)
: 2nd0.030~0.065 mm (0.0012~0.0026 in)0.1 mm (0.004 in)
Crankshaft:
Crank width “A” 59.95~60.00 mm (2.360~2.362 in)…
Runout limit “C” 0.03 mm (0.0012 in) 0.05 mm (0.0020 in)
Connecting rod big end
side clearance “D” 0.25~0.75 mm (0.010~0.030 in)…
Small end free play “F” 0.4~1.0 mm (0.016~0.039 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 44.0 mm (1.732 in) 42.0 mm (1.654 in)
Quantity 6 …
Clutch housing thrust clearance 0.17~0.23 mm (0.007~0.009 in) …
Clutch housing radial clearance 0.030~0.055 mm (0.001~0.002 in) …
Clutch release method Inner push, cam push …
EC212000
MAINTENANCE SPECIFICATIONSEC212100
ENGINE
5MW-9-30-2 7/3/00 2:19 PM Page 4

2-4
MAINTENANCE SPECIFICATIONSSPEC
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 ratchet type…
Air filter oil grade (oiled filter):Foam-air-filter oil or engine mixing oil…
Carburetor:USA, CDN, ZA,
EUROPE
AUS, NZ
Type/Manufacturer
PWK38S/KEIHIN¬…
I.D. mark 5MW00 5MW10…
Main jet (M.J.) #178 #180…
Main air jet (M.A.J) #200¬…
Jet needle-clip position (J.N.) N3EJ-2 N3CW-3…
Main nozzle (N.J.) ø2.9¬…
Cutaway (C.A.) #7¬…
Pilot jet (P.J.) #50 #55…
Pilot air screw (P.A.S.) 1 1-3/4…
(for reference only)
Valve seat size (V.S.)
ø3,8 mm (0,15 in)¬…
Starter jet (G.S.) #85¬…
Power jet (P.W.J.) #50 #55 …
Float arm height (F.H.) 5.5~7.5 mm¬…
(0.22~030 in)
Reed valve:
Thickness* 0.42 mm (0.017 in)…
Valve stopper height 10.3~10.7 mm (0.406~0.421 in)…
Valve bending limit…
0.2 mm (0.008 in)
Cooling:
Radiator core size:
Width 110 mm (4.33 in)…
Height 240 mm (9.45 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) 0.64 L (0.56 Imp qt, 0.68 US qt)…
Water pump:
Type Single-suction centrifugal pump…
5MW-9-30-2 7/3/00 2:20 PM Page 5

2-10
MAINTENANCE SPECIFICATIONSSPEC
M 6 ´ 1.0
M10 ´ 1.25
M10 ´ 1.25
M20 ´ 1.5
M 8 ´ 1.25
–
M 6 ´ 1.0
M 6 ´ 1.0
M 8 ´ 1.25
M10 ´ 1.25
M10 ´ 1.25
M10 ´ 1.25
M16 ´ 1.5
M14 ´ 1.5
M14 ´ 1.5
M14 ´ 1.5
M10 ´ 1.25
M10 ´ 1.25
M 8 ´ 1.25
M 5 ´ –
M 8 ´ 1.25
M 6 ´ 1.0
M 5 ´0.8
M 6 ´ 1.0
M 6 ´ 1.0
M 6 ´ 1.0
M 6 ´ 1.0
M 6 ´ 1.0
M 6 ´ 1.0
M 6 ´ 1.0
M 6 ´ 1.0
M 6 ´ 1.0
M 6 ´ 1.0
M 6 ´ 1.0 Rear brake reservoir tank and frame
Rear brake hose union bolt (caliper)
Rear brake hose union bolt (master cylinder)
Rear wheel axle and nut
Driven sprocket and wheel hub
Nipple (spoke)
Disc cover and rear brake caliper
Protector and rear brake caliper
Engine mounting:
Engine bracket and frame
Engine and frame (front)
Engine and frame (upper)
Engine and frame (lower)
Pivot shaft and nut
Relay arm and swingarm
Relay arm and connecting rod
Connecting rod and frame
Rear shock absorber and frame
Rear shock absorber and relay arm
Rear frame and frame
Swingarm and brake hose holder
Drive chain tensioner mounting
Chain support and swingarm
Seal guard and swingarm
Fuel tank mounting
Fuel tank and fuel cock
Fuel tank and seat set bracket
Fuel tank and hooking screw (fitting band)
Fuel tank and fuel tank bracket
Seat mounting
Side cover mounting
Air scoop mounting
Front fender mounting
Rear fender mounting
Number platePart to be tightened Thread size Q’tyTightening torque
Nm m•kg ft•lb
1
1
1
1
6
72
2
2
2
1
1
1
1
1
1
1
1
1
3
4
2
3
4
2
2
1
1
4
2
4
8
4
4
17
30
30
125
42
3
7
7
34
69
69
69
85
80
80
80
56
53
29
4
19
7
5
10
7
7
7
7
7
7
3
7
7
70.7
3.0
3.0
12.5
4.2
0.3
0.7
0.7
3.4
6.9
6.9
6.9
8.5
8.0
8.0
8.0
5.6
5.3
2.9
0.4
1.9
0.7
0.5
1.0
0.7
0.7
0.7
0.7
0.7
0.7
0.3
0.7
0.7
0.75.1
22
22
90
30
2.2
5.1
5.1
24
50
50
50
61
58
58
58
40
38
21
2.9
13
5.1
3.6
7.2
5.1
5.1
5.1
5.1
5.1
5.1
2.2
5.1
5.1
5.1
NOTE:
- marked portion shall be checked for torque tightening after break-in or before each race.
5MW-9-30-2 7/3/00 2:20 PM Page 11

2-12
GENERAL TORQUE SPECIFICATIONS/
DEFINITION OF UNITS
SPEC
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
ABTORQUE 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
5MW-9-30-2 7/3/00 2:20 PM Page 13

2-13
CABLE ROUTING DIAGRAMSPEC
EC240000
CABLE ROUTING DIAGRAM
1Cable guide
2Clamp
3“ENGINE STOP” button lead
4Throttle cable
5TPS (throttle position sensor)
lead
6Solenoid valve lead
7CDI unit
8CDI unit stay
9CDI unit band
0Air vent hose (left)
qTransmission oil breather hose
wOverflow hose
eAir vent hose (right)APass 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.
BClamp the throttle cable,
“ENGINE STOP” button lead and
CDI unit lead with the clamp
ends downward.
CPass the throttle cable, “ENGINE
STOP” button lead and CDI unit
lead over the radiator hose.
DClamp the clutch cable, throttle
cable, “ENGINE STOP” button
lead, TPS (throttle position sen-
sor) lead and solenoid valve lead
with the clamp ends downward.
In so doing, clamp the “ENGINE
STOP” button lead at its protect-
ing tube.
EClamp the clutch cable so that
the clamp passes with its ends
downward, as shown.
FPass the TPS (throttle position
sensor) lead and solenoid valve
lead through the cable guide.GClamp the TPS (throttle position
sensor) lead and solenoid valve
lead to the frame with the clamp
ends backward.
HPass the solenoid valve lead
through the carburetor clamp.
IPass the air vent hoses, overflow
hose and transmission oil
breather hose between the frame
and connecting rod.
JFit the CDI unit into the CDI unit
stay till it stops.
KInsert the CDI unit into the CDI
unit band till it stops.
LPass the TPS (throttle position
sensor) lead and solenoid valve
lead under the damper.
MClamp the air vent hoses.
NPass the air vent hoses, overflow
hose and transmission oil
breather hose so that all these
hoses do not contact the rear
shock absorber.
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2-13
SCHEMA DE CHEMINEMENT DES CABLES
KABELFÜHRUNGSÜBERSICHTPLAN
DIAGRAMMA DEL PASSAGGIO DEI CAVISPEC
KABELFÜHRUNGSÜBER-
SICHTPLAN
1Kabelführung
2Klemme
3
Leitungskabel des Motorstoppknopfes „ENGINE STOP”4Gasseil
5TPS-Leitungskabel (Drosselstellungssensor)6Magnetventilleitung
7CDI-Einheit
8Stütze der CDI-Einheit
9Band der CDI-Einheit
0Belüftungsschlauch (Links)
qGetriebeöl-Belüftungsschlauch
wÜberlaufschlauch
eBelüftungsschlauch (Rechts)
ADas Gasseil und den Leitungskabel des
Motorstoppknopfes „ENGINE STOP“
durch die Kabelführung führen. Vorde-
res Bandende am Gaskabel mit der
Kabelführung ausrichten.
BDrosselkabel festklemmen, Leitungska-
bel des Motorstoppknopfse „ENGINE
STOP“ und CDI-Einheitsleitung mit den
Klemmenden nach unten.
CDrosselkabel festklemmen, Leitungska-
bel des Motorstoppknopfes „ENGINE
STOP“ und CDI-Einheitsleitung über
dem Kühlerschlauch.
DKupplungskabel, Drosselkabel, Lei-
tungskabel des Motorstoppknopfes
“ENGINE STOP”, TPS-Leitungskabel
(Drosselstellungssensor) und Magnet-
ventilleitungskabel mit den Klemmenen-
den nach unten festklemmen. Dabei
wird das Leitungskabel des Motorstopp-
knopfes “ENGINE STOP” an seinem
Schutzrohr festgeklemmt.
E
Kupplungskabel so festklemmen, daß die
Klemme mit ihren Enden nach unten
durchgeführt wird, entsprechend der Abbil-
dung.
FTPS-Leitungskabel (Drosselstellungssen-
sor) und Magnetventilleitungskabel durch
die Kabelführung ziehen.
GTPS-Leitungskabel (Drosselstellungs-
sensor) und Magnetventilleitungskabel
mit den Klemmenden nach hinten am
Rahmen festklemmen.
H
Magnetventilleitung durch die Vergaser-
klemme führen.
IDie Belüftungsschläuche, den Überlauf-
schlauch und den Getriebeöl-Belüftungs-
schlauch zwischen dem Rahmen und der
Pleuelstange durchführen.
JDas Band der CDI-Einheit bis zum
Anschlag über die Stütze der CDI-Ein-
heit fühten.
K
CDI-Einheit bis zum Anschlag in die CDI-
Einheitsleiste einführen.
LTPS-Leitungskabel (Drosselstellungssen-
sor) und Magnetventilleitungskabel unter
dem Dämpfer durchführen.
MBelüftungsschläuche festklemmen.NDie Belüftungsschläuche, den Überlauf-
schlauch und den Getriebeöl-Belüftungs-
schlauch so durchführen, daß diese
Schläuche den Hinterrad-Stoßdämpfer
nicht berühren.
SCHEMA DE
CHEMINEMENT DES
CABLES
1Guide de câble
2Bride
3
Fil de bouton d’arrêt du moteur “ENGINE STOP”4Câble d’accélérateur
5Fil du TPS (capteur de position du papillon)6Fil d’électrovanne
7Bloc CDI
8Anorage du bloc CDI
9Bandeau du bloc CDI
0Tuyau de ventilation (gauche)
q
Tuyau de reniflard d’huile de boîte de vitesseswTuyau de trop-plein
eTuyau de ventilation (droit)
AFaire passer le câble d’accélérateur et le
fil du bouton d’arrêt du moteur “ENGI-
NE STOP” dans le guide de câble. Ali-
gner sur le guide-câble l’extrémité avant
du ruban du câble d’accélérateur.
BBridez le câble d’accélérateur, le fil du
bouton “ENGINE STOP” et le fil de
l’unité CDI en orientant les extrémités de
la bride vers le bas.
CFaites passer le câble d’accélérateur, le
fil du bouton “ENGINE STOP” et le fil
de l’unité CDI au-dessus de la durit de
radiateur.
DBridez le câble d’embrayage, le câble
d’accélérateur, le fil du bouton “ENGI-
NE STOP”, le fil du capteur de position
du papillon (TPS) et le fil de l’électro-
vanne en orientant les extrémités de la
bride vers le bas. Ce faisant, bridez le fil
du bouton “ENGINE STOP” sur sa gaine
de protection.
EBridez le câble d'embrayage de façon à
ce que la bride se présente avec les extré-
mités vers le bas comme illustré.
FFaites passer le fil du capteur de position
du papillon (TPS) et le fil de l’électro-
vanne dans le guide de câble.
GBridez le fil du capteur de position du
papilon (TPS) et le fil de l’électrovanne
au cadre en orientant les extrémités de la
bride vers l’arrière.
HFaites passer le fil de l’électrovanne dans
la bride du carburateur.
IFaire passer les tuyaux de ventilation, le
tuyau de trop-plein et le tuyau de renifi-
lard d’huile de transmission entre le
cadre et la bielle.
JAdapter complètement le bandeau du
bloc CDI sur l’ancrage du bloc CDI.
KIntroduisez à fond l’unité CDI dans le
collier de l’unité CDI.
LFaites passer le fil du capteur de position
du papillon (TPS) et le fil de l’électro-
vanne sous l’amortisseur.
MBridez les tuyaux de ventilation.
N
Faire passer les tuyaux de ventilation, le
tuyau de trop-plein et le tuyau de reniflard
d’huile de transmission de sorte qu’ils ne
touchent pas l’amortisseur arrière.
IC240000
DIAGRAMMA DEL
PASSAGGIO DEI CAVI
1Guida per cavi
2Brida
3
Conduttore del pulsante “ARRESTO MOTORE”4Cavo dell’acceleratore
5Conduttore TPS (sensore di posizione gas)6Conduttore elettrovalvola
7Unità CDI
8Supporto unità CDI
9Nastro dell’unità CDI
0Tubo flessibile dello sfiatatoio dell’aria
(sinistro)
qSfiato dell’olio per trasmissioni
wTubo flessibile di troppopieno
eTubo flessibile dello sfiatatoio dell’aria
(destro)
AFar passare il cavo dell’acceleratore e il
conduttore del pulsante “ARRESTO
MOTORE” nella guida per cavi. Allinea-
re con la guida per cavi l’estremità ante-
riore del nastro sul cavo dell’accelerato-
re.
BFermare il cavo del gas, il conduttore del
pulsante “ARRESTO MOTORE” e il con-
duttore dell’unità CDI con le estremità della
fascia rivolte verso il basso.
CFar scorrere il cavo del gas, il conduttore
del pulsante “ARRESTO MOTORE” e il
conduttore dell’unità CDI sopra il tubo del
radiatore.
DFermare il cavo della frizione, il cavo
dell’acceleratore, il conduttore del pulsante
di arresto motore, il sensore di posizione
gas TPS e il conduttore dell’elettrovalvola
con le estremità della fascia rivolte verso il
basso. Nell’effettuare questa operazione,
fissare il conduttore del pulsante “ARRE-
STO MOTORE” sul tubo di protezione.
EFissare il cavo della frizione in modo tale
che le estremità della fascetta siano rivolte
verso il basso, come illustrato.
FFar passare il conduttore TPS (sensore di
posizione gas) e l’elettrovalvola attraverso
la guida del cavo.
GFissare al telaio il conduttore TPS (sen-
sore di posizione dell’acceleratore) e
l’elettrovalvola con le estremità della
fascia all’indierto.
HFar scorrere il conduttore dell’elettrovalvola
attraverso la fascia del carburatore.
IFar passare i tubi di spurgo dell’aria, il tubo
di troppopieno e lo sfiato dell’olio di tra-
smissione tra il telaio e la biella.
JMontare la banda dell’unità CDI sul sup-
porto di quest’ultima fino a quando non
si arresta.
KInserire l’unità CDI nella fascia dell’unità
CDI fino a quando non si arresti.
LFar passare il conduttore TPS (sensore di
posizione gas) e il conduttore dell’elettro-
valvola sotto lo smorzatore di vibrazioni.
MFissare i tubi di sfiato.
NFar passare i tubi di sfiato dell’aria, il tubo
di troppopieno e lo sfiato dell’olio di tra-
smissione in modo che tutti questi tubi non
tocchino l’ammortizzatore posteriore.
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2-14
CABLE ROUTING DIAGRAMSPEC
1CDI magneto lead
2YPVS breather hose
3Clamp
4Clutch cable
5Radiator breather hose
6CDI unit lead
7Cable guideAPass the radiator breather hose
outside the engine bracket and
inside the down-tube.Pass the
radiator breather hose inside
the CDI magneto lead.
BClamp the CDI magneto lead,
radiator breather hose and
YPVS breather hose. In so
doing, clamp the CDI magneto
lead at the rear of the down-
tube with the clamp ends for-
ward.
CClamp the radiator breather
hose and CDI magneto lead at
the rear of the down-tube with
the clamp ends outward.
DPass the clutch cable a little for-
ward of the extreme left nut that
holds the cylinder head.EPass the radiator breather hose
and CDI magneto lead in front
of the radiator hose.
FPass the radiator breather hose
and CDI magneto lead between
the frame and radiator.
GAlign the top of the brake hose
neck with the brake hose holder
bottom.
HPass the brake hose in front of
the axle boss,then fit it into the
hose groove so that the brake
hose does not contact the nut
(wheel axle).
IFit the brake hose into the guide
on the protector.
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2-15
CABLE ROUTING DIAGRAMSPEC
1Brake hose holder
2Master cylinder
3Brake hose
4Reservoir hose
5Hose guide
6Clamp
7High tension cord
8Ignition coil
9Clutch cable
0Cable guide
qGround lead
wRadiator breather hose
eCDI magneto lead
rThrottle cable
tCDI unit lead
y“ENGINE STOP” button lead
uFuel tank damper
iEngine bracket
APass the brake hose into the
brake hose holder.BIf the brake hose contacts the
spring (rear shock absorber),
correct its twist.
CInstall the brake hose so that its
pipe portion directs as shown
and lightly touches the projec-
tion on the master cylinder.
DPass the reservoir hose
between the brake hose and
swingarm bracket.
EPass the reservoir hose into the
hose guide.
FClamp the high tension cord,
throttle cable, TPS (throttle posi-
tion sensor) and solenoid valve
lead so that the high tension
cord does not contact the
engine bracket installation nuts.
G
Fasten the ground lead together
with the front installation portion
of the ingnition coil.
HPass the clutch cable into the
cable guide.
IPosition the CDI magneto lead
coupler between the radiators.
JInstall the brake hose to the
caliper with the paint on the pipe
facing the caliper and with the
pipe contacting the caliper pro-
jection.
KPass the radiator breather hose
between the frame and radiator
hose so that it is not kinked or
wedged.
LPass the throttle cable, CDI unit
lead, “ENGINE STOP” button
lead and clutch cable between
the fuel tank damper tube ends.
5MW-9-30-2 7/3/00 2:26 PM Page 54