engine YAMAHA YZ250LC 2002 Owner's Manual

1-16
TORQUE-CHECK POINTS
GEN
INFO
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
Rear Brake pedal to frame
Brake disc to wheel
Tighening of union bolt
Master cylinder to frame
Tightening of air bleeder
Fuel system Fuel tank to fuel cock
NOTE:
Concerning the tightening torque, refer to “
MAINTENANCE SPECIFICATIONS” section in
the CHAPTER 2.
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1-17
CLEANING AND STORAGE
GEN
INFO
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
resulted from improper high pressure
detergent applications such as those avail-
able 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.
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1-18
CLEANING AND STORAGE
GEN
INFO
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
machine 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.
5NX-9-30-1 6/5/01 3:54 PM Page 42

2-1
GENERAL SPECIFICATIONSSPEC
Model name: YZ250LC (EUROPE)
YZ250P1 (USA)
YZ250(P) (CDN, AUS, NZ, ZA)
Model code number: 5NX1 (USA, CDN, ZA)
5NX2 (EUROPE)
5NX4 (AUS, NZ)
Dimensions:USA, ZAAUS, NZ EUROPE CDN
Overall length 2,183 mm←2,182 mm←
(85.9 in) (85.9 in)
Overall width 827 mm←←←
(32.6 in)
Overall height 1,309 mm 1,296 mm 1,302 mm 1,307 mm
(51.5 in) (51.0 in) (51.3 in) (51.5 in)
Seat height 991 mm←990 mm←
(39.0 in) (39.0 in)
Wheelbase 1,481 mm←1,485 mm←
(58.3 in) (58.5 in)
Minimum ground clearance 395 mm←393 mm←
(15.6 in) (15.5 in)
Basic weight:
With oil and full fuel tank 105.0 kg (231 lb)
Engine:
Engine type Liquid cooled 2-stroke, gasoline
Cylinder arrangement Single cylinder, forward inclined
Displacement 249 cm
3(8.76 lmp oz, 8.42 US oz)
Bore ×Stroke 66.4 ×72 mm (2.614 ×2.835 in)
Compression ratio 9.1~10.6 : 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 0.75 L (0.66 Imp qt, 0.79 US qt)
Total amount 0.80 L (0.70 Imp qt, 0.85 US qt)
Coolant capacity (including all routes): 1.20 L (1.06 Imp qt, 1.27 US qt)
Air filter: Wet type element
Fuel:
Type Except for ZA: Premium unleaded gasoline
only with a research octane
number of 95 or higher
For ZA: Premium gasoline
Tank capacity 8.0 L (1.76 Imp gal, 2.11 US gal)
EC200000
SPECIFICATIONSEC211000
GENERAL SPECIFICATIONS
2
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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 50.0 mm (1.969 in) 48.0 mm (1.890 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
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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 5NX1 00 5NX2 10…
Main jet (M.J.) #178 #175…
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 #52…
Pilot air screw (P.A.S.) 1 1-3/8…
(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←…
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 107.8 mm (4.24 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) 0.63 L (0.55 Imp qt, 0.67 US qt)…
Water pump:
Type Single-suction centrifugal pump…
5NX-9-30-2 6/7/01 1:57 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 ×0.8
M 4 ×0.7
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 8 × 1.25
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
Swingarm and patch
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
4
2
3
4
2
2
1
1
4
2
2
6
4
4
17
30
30
125
42
3
7
7
34
69
69
69
85
80
80
80
56
53
29
1
2
19
7
6
10
7
7
7
7
19
7
4
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
0.1
0.2
1.9
0.7
0.6
1.0
0.7
0.7
0.7
0.7
1.9
0.7
0.4
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
0.7
1.4
13
5.1
4.3
7.2
5.1
5.1
5.1
5.1
13
5.1
2.9
5.1
5.1
5.1
NOTE:
- marked portion shall be checked for torque tightening after break-in or before each race.
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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
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2-13
CABLE ROUTING DIAGRAMSPEC
EC240000
CABLE ROUTING DIAGRAM
1Fuel tank breather hose
2Cable guide
3Throttle cable
4Clamp
5Clutch cable
6Wireharness
7“ENGINE STOP” button lead
8CDI unit
9CDI unit stay
0CDI unit band
qTPS (throttle position sensor)
lead
wSolenoid valve lead
eAir vent hose (left)
rTransmission oil breather hose
tOverflow hose
yAir vent hose (right)APass the fuel tank breather hose
between the handlebar and ten-
sion bar, then insert its end into
the hole of the number plate.
BPass 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.
CPass the throttle cable and
“ENGINE STOP” button lead
over the radiator hose.
DClamp the throttle cable and
“ENGINE STOP” button lead with
the clamp ends downward.
EPass the clutch cable a little for-
ward of the extreme left nut that
holds the cylinder head.
FPass the wireharness between
the engine brackets.GPass the air vent hoses, overflow
hose and transmission oil
breather hose between the frame
and connecting rod.
HFit the CDI unit band into the CDI
unit stay till it stops.
IInsert the CDI unit into the CDI
unit band till it stops.
JClamp the TPS (throttle position
sensor) lead and solenoid valve
lead at the side of the TPS with
the clamp ends backward.
KClamp the air vent hoses.
LPass 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
1Kraftstofftank - Belüftungsschlauch
2Kabelführung
3Gasseil
4Klemme
5Kupplungskabel
6Kabelbaum
7Leitungskabel des Motorstoppknopfes
„ENGINE STOP”
8CDI - Einheit
9Stütze der CDI - Einheit
0Band der CDI - Einheit
qTPS - Leitungskabel (Drosselstellungs-
sensor)
wMagnetventilleitung
eBelüftungsshlauch (Links)
rGetriebeöl-Belüftungsschlauch
tÜberlaufschlauch
yBelüftungsschlauch (Rechts)
ADen Kraftstofftank-Belüftungsschlauch
zwischen der Lenkstange und der Zug-
stange durchführen und danach sein
Ende in die Bohrung des Nummern-
schildes einsatzen.
BDas Gasseil und den Leitungskabel des
Motorstoppknopfes „ENGINE STOP“
durch die Kabelführung führen. Vorde-
res Bandende am Gaskabel mit der
Kabelführung ausrichten.
CGaskabel und „ENGINE STOP“ Leitung
über den Kühlerschlauch führen.
DGaskabel und „ENGINE STOP“ Leitung
mit den Enden der Verschlussklemmen
nach unten festklemmen.
E
Kupplungskabel etwas vor der äußersten
linken Mutter durchführen, die den Zylin-
derkopf befestigt.
FKabelbaum zwischen den Motoraufhän-
gungen durchführen.
G
Die Belüftungsschläuche, den Überlauf-
schlauch und den Getriebeöl-Belüftungs-
schlauch zwischen dem Rahmen und der
Pleuelstange durchführen.
HCDI-Einheitsleiste bis zum Anschlag in
die CDI-Einheit einführen.
I
CDI-Einheit bis zum Anschlag in die CDI-
Einheitsleiste einführen.
JTPS-Leitung (Gaspositionssensor) und
Magnetventilleitung mit den
Enden den Verschlussklemmen nach
hinten an der Seite des TPS befestigen.
K
Belüftungsschläuche festklemmen.LDie Belüftungsschläuche, den Überlauf-
schlauch und den Getriebeöl-Belüftungs-
schlauch so durchführen, daß diese
Schläuche den Hinterrad-Stoßdämpfer
nicht berühren.
SCHEMA DE
CHEMINEMENT DES
CABLES
1Tuyau de reniflard de réservoir à essence
2Guide de câble
3Câble d’accélérateur
4Bride
5Câble d’embrayage
6Faisceau de fils
7Fil de bouton d’arrêt du moteur “ENGI-
NE STOP”
8Bloc CDI
9Anorage du bloc CDI
0Bandeau du bloc CDI
qFil du TPS (capteur de position du
papillon)
wFil d’électrovanne
eTuyau de ventilation (gauche)
r
Tuyau de reniflard d’huile de boîte de vitessestTuyau de trop-plein
yTuyau de ventilation (droit)
AFaire 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.
BFaire 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.
CFaites passer le câble d’accélérateur et le
fil du bouton d’arrât du moteur “ENGI-
NE STOP” au-dessus du tuyau du radia-
teur.
DBridez le câble d’accélérateur et le fil du
bouton d’arrât du moteur “ENGINE
STOP” en orientant les extrémités de la
bride vers le bas.
EFaites passer le câble d’embrayage en
peu en avant de l’écrou de fixation extrê-
me gauche de la culasse.
FFaites passer le faisceau de fils entre les
supports du moteur.
GFaire 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.
HAjustez le bandeau du bloc CDI dans le
support du bloc CDI jusqu’en butée.
IIntroduisez à fond l’unité CDI dans le
collier de l’unité CDI.
JBridez le fil TPS (capteur de position de
papillon) et le fil d’électrovanne en
orientant les extrémités de la bride vers
l’arrière.
KBridez les tuyaux de ventilation.
L
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
1Sfiato del serbatoio del carburante
2Guida per cavi
3Cavo dell’acceleratore
4Brida
5Cavo della frizione
6Complesso conduttori
7Conduttore del pulsante “ARRESTO
MOTORE”
8Unità CDI
9Supporto unità CDI
0Nastro dell’unità CDI
qConduttore TPS (sensore di posizione
gas)
wConduttore elettrovalvola
eTubo flessibile dello sfiatatoio dell’aria
(sinstro)
rSfiato dell’olio per trasmissioni
tTubo flessibile di troppopieno
yTubo flessibile dello sfiatatoio dell’aria
(destro)
AFar passare lo sfiato del serbatoio puran-
te fra il manubrio e il tirante, quindi inse-
rirne l’estremità nel foro della targa.
BFar 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.
CFar passare il cavo dell'acceleratore e il
conduttore del pulsante "ARRESTO
MOTORE" sopra il tubo del radiatore.
DFissare il cavo dell'acceleratore e il con-
duttore del pulsante "ARRESTO MOTO-
RE" con le estremità della fascia di ser-
raggio rivolte verso il basso.
EFar passare il cavo della frizione un po’ più
avanti rispetto al dado all’estrema sinistra
che regge la testa del cilindro.
FFar passare il complesso conduttori tra le
staffe del motore.
GFar 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.
HInserire il nastro dell'unità CDI sul sup-
porto dell'unità CDI finché non si arresta.
IInserire l’unità CDI nella fascia dell’unità
CDI fino a quando non si arresti.
JAgganciare il conduttore del TPS (senso-
re di posizione dell'acceleratore) e il con-
duttore della valvola del solenoide sul
fianco del TPS con le estremità della
fascia di serraggio rivolte all'indietro.
KFissare i tubi di sfiato.
LFar 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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