engine YAMAHA WR 400F 2002 Service Manual

2 - 40
SPECCABLE ROUTING DIAGRAM
1Coolant reservoir tank
breather hose
2Clamp
3Ignition coil
4High tension cord
5CDI unit
6CDI unit band
7“ENGINE STOP” button
lead
8Throttle cable (pull)
9Throttle cable (return)
0Radiator (left)
ARadiator (right)
BDecompression cable
CCDI unit stay (frame)ÅFasten the coolant reservoir tank
breather hose and carburetor
breather hoses together with a
plastic locking tie.
ıFasten the ignition coil lead to the
frame with a plastic band.
ÇPass the ignition coil lead (in the
sub wire harness) so that it does
not contact the carburetor and
rear shock absorber and connect
it with the lead from the ignition
coil on the inside of the frame.
ÎFasten the ignition coil and
ground lead to the frame with the
bolt.
‰Pass the throttle cables over the
high tension cord.
ÏPass the throttle cables along the
outer side of the CDI unit leads.ÌFasten the CDI unit leads and
“ENGINE STOP” button lead to
the frame at the protector of the
CDI unit leads with a plastic lock-
ing tie.
ÓFit the boot over the coupler.
ÈPass the throttle cables between
the top radiator mounting boss
and middle radiator mounting
boss.
ÔPass the CDI unit lead and
“ENGINE STOP” button lead over
the top radiator mounting boss.
Pass the throttle cables and
“ENGINE STOP” button lead
through the cable guide.
ÒCross the pull and return throttle
cables before the radiator.
˜Insert the CDI unit band over the
CDI unit stay (frame) as far as
possible.

SPEC
2 - 40
CHEMINEMENT DES CABLES
KABELFÜHRUNG
DIAGRAMA DE RUTA DE CABLES
1Kühlmittelausgleichstank-Lüftungs-
schlauch
2Kabelbinder
3Zündspule
4Hochspannungskabel
5CDI-Zündbox
6CDI-Zündbox-Befestigungsband
7Motorstoppschalter-Kabel
8Gasseilzug (Zug)
9Gasseilzug (Rückzug)
0Kühler (links)
AKühler (rechts)
BDekompressionszug
CCDI-Zündbox-Halterung
ÅDen Kühlmittelausgleichstank-Lüf-
tungsschlauch und die Vergaser-Lüf-
tungsschläuche zusammen mit ei-
nem Kabelbinder verbinden.
ıDas Zündspulen-Kabel mit mehrf. ver-
wendb. Kabelbinder am Rahmen be-
festigen.
ÇDie Zündspulenleitung (im Nebenka-
belbaum) so durchführen, daß sie
nicht den Vergaser und hinteren
Stoßdämpfer berührt und mit der
Leitung von der Zündspule innen am
Rahmen verbinden.
ÎDie Zündspulen- und Massekabel mit
am Rahmen festschrauben.
‰Die Gasseilzüge über das Hochspan-
nungskabel führen.
ÏDie Gasseilzüge vor dem CDI-Zünd-
box-Leitungen führen.
ÌDie Kabel der CDI-Einheit und das
Motorstoppschalterkabel zum Rah-
men am Protektor der CDI-Einheit-
Kabel mit einem Einweg-Kabelbinder
befestigen.
ÓDie Tülle über den Koppler setzen.
ÈDie Gasseilzüge zwischen der oberen
Kühlerhalterung und der mittleren
Kühlerhalterung führen.
ÔDas CDI-Einheit-Kabel und am Motor-
stoppschalterkabel über die obere
Kühlerhaltebüchse führen.
Die Gaszüge, das Motorstoppschal-
terkabel und das CDI-Einheit-Kabel
durch die Seilzugführung führen.
ÒDie Gaszug- und -rückzugseile vor
dem Kühler überkreuzen.
˜Das CDI-Zündbox-Befestigungsband
so weit wie möglich über der CDI-
Zündbox-Halterung führen. 1Flexible de reniflard du réservoir de
liquide de refroidissement
2Bride
3Bobine d’allumage
4Cordon de haute tension
5Bloc CDI
6Attache de bloc CDI
7Fil de bouton d’arrêt de moteur “ENGINE
STOP”
8Câble d’accélérateur (tirer)
9Câble d’accélérateur (rentrer)
0Radiateur (gauche)
ARadiateur (droit)
BCâble du décompresseur
CSupport du bloc CDI (cadre)
ÅAttacher le reniflard du réservoir de
liquide de refroidissement et le reniflard
de carburateur ensemble à l’aide d’une
attache en plastique.
ıAttacher le fil de bobine d’allumage au
cadre à l’aide d’une attache en plastique.
ÇFaire passer le fil de bobine d’allumage
(dans le faisceau de fils secondaires) de
sorte qu’il ne touche pas le carburateur et
l’amortisseur arrière et le raccorder avec
le fil de la bobine d’allumage sur l’inté-
rieur du cadre.
ÎAttacher le fil de bobine d’allumage et le
fil de la masse au cadre à l’aide d’un bou-
lon.
‰Faire passer les câbles d’accélération par-
dessus le cordon de haute tension.
ÏFaire passer les câbles d’accélération par-
devant les fils du bloc CDI.
ÌAttacher les fils du bloc CDI et le fil du
bouton d’arrêt du moteur “ENGINE
STOP” au cadre à la hauteur de la protec-
tion des fils du bloc CDI avec une attache
en plastique.
ÓEmboîter la tétine sur le coupleur.
ÈFaire passer les câbles d’accélération
entre la noix de montage supérieur et cen-
trale du radiateur.
ÔFaire passer le reniflard du radiateur à
l’extérieur des fils du bloc CDI et du fil
du bouton d’arrêt du moteur “ENGINE
STOP”.
Faire passer les câbles d’accélération, le
fil du bouton d’arrêt du moteur “ENGINE
STOP” et le fil du bloc CDI dans le guide
des câbles.
ÒCroiser les deux câbles d’accélérateur
devant le radiateur.
˜Insérer l’attache du bloc CDI par-dessus
le support du bloc CDI (cadre) aussi loin
que possible.1Tubo respiradero del depósito de reserva
del refrigerante
2Abrazadera
3Bobina de encendido
4Cable de alta tensión
5Unidad CDI
6Banda de la unidad CDI
7Cable del botón de parada del motor
“ENGINE STOP”
8Cable del acelerador (tirar)
9Cable del acelerador (retornar)
0Radiador (izquierdo)
ARadiador (derecho)
BCable de descompresión
CSoporte de la unidad CDI (bastidor)
ÅSujetar el tubo respiradero del depósito de
reserva del refrigerante y los tubos respi-
raderos del carburador conjuntamente con
mediante una conexión plástica de cierre.
ıSujetar el cable de la bobina de encendido
al bastidor con una banda plástica.
ÇPasar el cable de la bobina de encendido
(del sub-cableado) de forma que no esté
en contacto con el carburador y con el
amortiguador trasero y conectarlo con el
cable que procede de la bobina de encen-
dido de la parte interior del bastidor.
ÎSujetar la bobina de encendido y cable de
tierra al bastidor con el perno.
‰Pasar los cables del acelerador sobre el
cable de alta tensión.
ÏPasar los cables del acelerador por el lado
exterior de los cables de la unidad CDI.
ÌSujetar los cables de la unidad CDI y el
cable del botón de parada del motor
“ENGINE STOP” al bastidor en el pro-
tector de los cables de la unidad CDI con
una conexión plástica de cierre.
ÓColocar lafunda encima del alcoplador.
ÈPasar los cables del acelerador entre el
buje de montaje del radiador superior y el
buje de montaje del radiador medio.
ÔPasar el cable de la unidad CDI y el cable
del botón de parada del motor “ENGINE
STOP” por encima del buje de montaje
del radiador.
Pasar los cables del acelerador y el cable
del botón de parada del motor “ENGINE
STOP” a través de la guía del cable.
ÒCruzar los cables de avance y retroceso
del acelerador antes de llegar al radiador.
˜Insertar la banda de la unidad CDI por
encima del soporte de la unidad CDI (bas-
tidor )lo máximo posible.

2 - 43
SPECCABLE ROUTING DIAGRAM
1Throttle cable
2Lights switch
3Lights switch lead
4Clamp
5Decompression cable
6Clutch cable
7Hose guide
8Trip meter
9Brake hose
0“ENGINE STOP” button leadÅFasten the “ENGINE STOP” button lead to the handlebar with the
plastic band.
ıPass the throttle cables between the handle crown and trip meter.
ÇPass the lights switch leads in front of the “ENGINE STOP” button
lead, then pass the head light lead (of the lights switch leads) in
front of the head pipe.
ÎInstall the trip meter cable so that its bent portion faces the chassis
rear.
‰Install the brake hose so that it contacts the master cylinder projec-
tion and that its bent portion faces downward.

SPEC
2 - 43
CHEMINEMENT DES CABLES
KABELFÜHRUNG
DIAGRAMA DE RUTA DE CABLES
1Gaszug
2Dekompressionshebel
3Lichtschalterkabel
4Kabelbinder
5Dekompressionszug
6Kupplungszug
7Kabelführung
8Tageskilometerzähler
9Bremsschlauch
0Motorstoppschalter-Kabel
ÅDas Motorstoppschalter-Kabel mit
mehrf. verwendb. Kabelbinder am
Lenker befestigen.
ıDie Gaszüge zwischen obere Gabel-
brücke und Tageskilometerzähler füh-
ren.
ÇDie Lichtschalterleitung vor der Lei-
tung des “MOTORSTOPPSCHAL-
TERS” durchführen, und die Schein-
werferleitung (der Lichtschalterleitung)
vor der Frontröhre verlegen.
ÎDie Tageskilometerzählerwelle so
montieren, daß ihre Krümmung zum
Rahmnehinterteil weist.
‰Der Metallstutzen des Brems-
schlauchs muß an der Nase des
Hauptbremszylinders anliegen und
die Krümmung nach unten weisen. 1Câble d’accélération
2Interrupteur lumières
3Fil de l’interrupteur lumières
4Bride
5Câble du décompresseur
6Câble d’embrayage
7Guide de flexible
8Compteur de vitesse
9Tuyau de frein
0Fil de bouton d’arrêt du moteur
“ENGINE STOP”
ÅFixer le fil de bouton d’arrêt du moteur
“ENGINE STOP” au guidon à l’aide
d’une attache en plastique.
ıFaire passer le câbles d’accélération entre
la couronne de guidon et le totalisateur
journalier.
ÇFaire passer les fils de l’interrupteur des
lumières devant le fil de bouton d’arrêt de
moteur “ENGINE STOP” et amener le fil
de prophare (du fil de l’interrupteur des
lumières) devant le tube de direction.
ÎMonter le câble du totalisateur journalier
en dirigeant sa partie recourbée vers
l’arrière du cadre.
‰Monter le flexible de frein en veillant à ce
qu’il touche la projection du maître cylin-
dre et que sa partie recourbée soit dirigée
vers le bas.1Cable del acelerador
2Interruptor de las luces
3Cable del interruptor de las luces
4Abrazadera
5Cable de descompresión
6Cable del embrague
7Guía del tubo
8Medidor de trayecto
9Tubo del freno
0Cable del botón de parada del motor
“ENGINE STOP”
ÅSujetar el cable del botón de parada del
motor “ENGINE STOP” al manillar con
una banda plástica.
ıPasar los cables del acelerador entre la tija
superior del manillar y el medidor de tra-
yecto.
ÇPasar el cable del interruptor de las luces
por delante del cable del botón de parada
del motor “ENGINE STOP” y traer el
cable de faro (del cable de interruptor de
las luces) enfrenbe del tubo del cabezal.
ÎInstalar el cable del medidor de trayecto
de forma que su parte doblada quede
orientada hacia el chasis trasero.
‰Instalar el tubo de freno de forma que
quede en contacto el saliente del cilindro
principal y su parte doblada quede orien-
tada hacia abajo.

3 - 1
INSP
ADJ
MAINTENANCE INTERVALS
EC300000
REGULAR INSPECTION AND ADJUSTMENTS
MAINTENANCE INTERVALS
The following schedule is intended as a general guide to maintenance and lubrication. Bear in mind
that such factors as weather, terrain, geographical location, and individual usage will alter the
required maintenance and lubrication intervals. If you are a doubt as to what intervals to follow in
maintaining and lubricating your machine, consult your Yamaha dealer.
ItemAfter
break-inEvery
race
Every
third
or
500 km
(300 mi)Every
fifth
or
1,000 km
(600 mi)
As re-
quiredRemarks
ENGINE OIL
Replace
●●
OIL FILTER
Clean
●●
VALVES
Check the valve clearances.
Inspect
Replace
●●
●
●The engine must be cold.
Check the valve seats and
valve stems for wear.
VALVE SPRINGS
Inspect
Replace
●
●Check the free length and
the tilt.
VALVE LIFTERS
Inspect
Replace
●
●Check for scratches and
wear.
CAMSHAFTS
Inspect
Replace
●
●Inspect the camshaft sur-
face.
CAMSHAFT SPROCKETS
Inspect
Replace
●
●Check for wear on the
teeth and for damage.
PISTON
Inspect
Clean
Replace
●●
●
●Inspect crack
Remove carbon
PISTON RING
Inspect
Replace
●
●●Check ring end gap
PISTON PIN
Inspect
Replace
●
●
CYLINDER HEAD
Inspect and clean
●
Remove carbon
Change gasket
CYLINDER
Inspect and clean
Replace
●
●Inspect score marks
Inspect wear
CLUTCH
Inspect and adjust
Replace
●●
●
Inspect housing, friction
plate, clutch plate and
spring
TRANSMISSION
Inspect
Replace bearing
●
●

3 - 4
INSP
ADJ
PRE-OPERATION INSPECTION AND MAINTENANCE
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.
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator filler cap.
Check that the coolant level is correct in the coolant reservoir
tank.
Check the cooling system for leakage.P.3-5 ~ 9
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the
fuel line for leakage.P.1-14
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-14 ~ 18
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-10
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-10 ~ 11
Brakes Check the play of front brake and effect of front and rear brake. P.3-26 ~ 32
ChainCheck chain slack and alignment. Check that the chain is lubri-
cated properly.P.3-33 ~ 36
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-44 ~ 45
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-45 ~ 46
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-36 ~ 43
Cables (wires)Check that the clutch and throttle cables move smoothly. 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.—
Sprocket Check that the driven sprocket tightening bolt is not loose. P.3-33
Lubrication Check for smooth operation. Lubricate if necessary. P.3-47
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-19
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-6
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs
before racing? Are inspection and maintenance completely
done?P.7-1 ~ 22

3 - 5
INSP
ADJ
EC350000
ENGINE
COOLANT LEVEL INSPECTION
WARNING
Do not remove the radiator cap 1, drain
bolt and hoses when the engine and radia-
tor are hot. Scalding hot fluid and steam
may be blown out under pressure, which
could cause serious injury.
When the engine has cooled, place a thick
towel over the radiator cap, slowly rotate
the cap counterclockwise to the detent.
This procedure allows any residual pres-
sure to escape. When the hissing sound
has stopped, press down on the cap while
turning counterclockwise and remove it.
CAUTION:
Hard water or salt water is harmful to the
engine parts. You may use distilled water, if
you can’t get soft water.
1. Place the machine on a level place, and
hold it in an upright position.
2. Inspect:
Coolant level
Coolant level should be between the
maximum a and minimum b marks.
Coolant level is below the “LOW” level
line → Add soft water (tap water) up to
the proper level.
3. Start the engine and let it warm up for
several minutes.
4. Turn off the engine and check the coolant
level again.
NOTE:
Before checking the coolant level, wait a few
minutes until the coolant settles.
LOWFULLCOOLANT
a
b
COOLANT REPLACEMENT
WARNING
Do not remove the radiator cap when the
engine is hot.
ENGINE/COOLANT LEVEL INSPECTION/
COOLANT REPLACEMENT

3 - 6
INSP
ADJ
COOLANT REPLACEMENT
CAUTION:
Take care so that coolant does not splash
on painted surfaces. If it splashes, wash it
away with water.
1. Place a container under the engine.
2. Remove:
Seat
Refer to ”SEAT FUEL TANK AND SIDE
COVERS” section in the CHAPTER 4.
3. Disconnect:
Coolant reservoir hose 1
Drain the coolant completely.
4. Connect:
Coolant reservoir hose
LOWFULLCOOLANT1
5. Remove:
Engine guard 1
Coolant drain bolt 2
6. Remove:
Radiator cap
Drain the coolant completely.
7. Clean:
Cooling system
Thoroughly flush the cooling system
with clean tap water.
8. Install:
Copper washer
Coolant drain bolt
Engine guard
Bolt [engine guard (front)]
Bolt [engine guard (rear)]
New
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..34 Nm (3.4 m · kg, 24 ft · lb)
T R..23 Nm (2.3 m · kg, 17 ft · lb)

3 - 7
INSP
ADJ
COOLANT REPLACEMENT
9. Fill:
Radiator
Engine
To specified level.
CAUTION:
Do not mix more than one type of ethyl-
ene glycol antifreeze containing corro-
sion inhibitors for aluminum engine.
Do not use water containing impurities or oil.
Recommended coolant:
High quality ethylene glycol
anti-freeze containing
anti-corrosion for
aluminum engine
Coolant 1 and water
(soft water) 2 mixing ratio:
50%/50%
Coolant capacity:
1.2 L (1.06 Imp qt, 1.27 US qt)
Handling notes of coolant:
The coolant is harmful so it should be han-
dled with special care.
WARNING
When coolant splashes to your eye.
Thoroughly wash your eye with water
and see your doctor.
When coolant splashes to your clothes.
Quickly wash it away with water and
then with soap.
When coolant is swallowed.
Quickly make him vomit and take him
to a doctor.
10. Install:
Radiator cap
11. Fill:
Coolant reservoir tank
Midway a between maximum and min-
imum marks on the tank.
LOWFULLCOOLANTa

3 - 8
INSP
ADJRADIATOR CAP INSPECTION/
RADIATOR CAP OPENING PRESSURE INSPECTION
12. Install:
Coolant reservoir cap
13. Start the engine and let it warm up for
several minutes.
14. Turn off the engine and inspect the cool-
ant level.
Refer to “COOLANT LEVEL INSPEC-
TION” section.
NOTE:
Before checking the coolant level wait a few
minutes until the coolant settles.
RADIATOR CAP INSPECTION
1. Inspect:
Seal (radiator cap) 1
Valve and valve seat 2
Crack/damage → Replace.
Fur deposits 3 → Clean or replace.
EC356001
RADIATOR CAP OPENING PRESSURE
INSPECTION
1. Attach:
Radiator cap tester 1 and adapter 2
NOTE:
Apply water on the radiator cap seal.
3Radiator cap
2. Apply the specified pressure.
Radiator cap tester:
YU-24460-01/90890-01325
Adapter:
YU-33984/90890-01352
Radiator cap opening pressure:
110 kPa (1.1 kg/cm2, 15.6 psi)