2000 YAMAHA WR 400F oil

ENG
4 - 27
CYLINDER HEAD
CYLINDER HEAD
CYLINDER HEAD
Extent of removal:1 Cylinder head removal
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Radiator Refer to “RADIATOR” section.
Carburetor Refer to “CARBURETOR” section.
Camshaft Refer to “CAMSHAFTS” section.
1 Decompression cable 1
2 Cable guide 1
3 Bolt 1
4 Decompression shaft 1
5 Oil delivery pipe 1
6 Nut (M6) 2
7 Nut (M8) 2
8 Bolt (L = 150 mm) 2
9 Bolt (L = 160 mm) 2
10 Cylinder head 1
1

ENG
4 - 29
CULASSE
ZYLINDERKOPF
CULATA
PRÜFUNG
Zylinderkopf
1. Entfernen:
lÖlkohleablagerungen (im
Brennraum)
Einen abgerundeten Scha-
ber verwenden.
HINWEIS:
Keine scharfkantigen Gegenstände
benutzen, um Beschädigungen und
Kratzer an folgenden Stellen zu ver-
meiden:
lZündkerzenbohrung
lVentilsitze
2. Kontrollieren:
lZylinderkopf
Kratzer/Beschädigungen ®
Erneuern.
3. Messen:
lZylinderkopf-Verzug
Grenzwert überschritten ®
Planschleifen.
ZUSAMMENBAU UND MONTAGE
1. Montieren:
lZylinderkopf
lSchrauben (1–4)
lSchraube (5)
lMuttern (6, 7)
lMuttern (8, 9)
HINWEIS:
Die numerierte Reihenfolge laut Ab-
bildung befolgen. Schrauben und
Muttern in zwei Arbeitsschritten fest-
ziehen.
Zylinderkopf-Verzugs-
grenze
unter 0,05 mm
Arbeitsschritte
lLineal und Fühlerlehre über den
Zylinderkopf legen.
lVerzug mit der Fühlerlehre
messen.
lIst die Verzugsgrenze über-
schritten, den Zylinderkopf
planschleifen.
lDen Zylinderkopf mit Naßschleif-
papier (Körnung 400–600) auf ei-
ner planen Platte in einer Achter-
bewegung abschleifen.
HINWEIS:
Den Zylinderkopf mehrmals dre-
hen, um eine ebene Oberfläche
zu gewährleisten.
T R..44 Nm (4,4 m · kg)
T R..10 Nm (1,0 m · kg)
T R..20 Nm (2,0 m · kg)
T R..10 Nm (1,0 m · kg)
CONTROLE
Culasse
1. Eliminer:
lDépôt de calamine
(de la chambre de combustion)
Utiliser un grattoir arrondi.
N.B.:
Ne pas utiliser d’instrument pointu pour
éviter d’endommager ou de rayer:
lFilets de bougies
lSièges de soupape
2. Contrôler:
lCulasse
Rayures/endommagement ®
Remplacer.
3. Mesurer:
lDéformation de la culasse
Hors spécifications ® Surfa-
cer.
ASSEMBLAGE ET MONTAGE
1. Monter:
lCulasse
lBoulon (1 à 4)
lBoulon (5)
lEcrou (6, 7)
lEcrou (8, 9)
N.B.:
Suivre l’ordre numérique montré sur
l’illustration. Serrer les boulons et les
écrous en deux étapes.
Limite de déformation de
la culasse:
Moins de 0,05 mm
(0,002 in)
Etapes de la mesure de la limite de
déformation et du surfaçage:
lPlacer une règle et une jauge
d’épaisseur sur la culasse.
lUtiliser une jauge d’épaisseur pour
mesurer la déformation.
lSi la déformation est hors spécifi-
cations, surfacer la culasse.
lMettre un morceau de toile émeri
n˚ 400 à 600 humide sur une pla-
que à surfacer et surfacer la culasse
en décrivant des “huit”.
N.B.:
Tourner la culasse plusieurs fois pour
obtenir une surface lisse.
T R..44 Nm (4,4 m · kg, 32 ft · lb)
T R..10 Nm (1,0 m · kg, 7,2 ft · lb)
T R..20 Nm (2,0 m · kg, 14 ft · lb)
T R..10 Nm (1,0 m · kg, 7,2 ft · lb)
INSPECCIÓN
Culata
1. Eliminar:
lDepósitos de carbonilla (de las
cámaras de combustión)
Utilice una rasqueta redon-
deada.
NOTA:
No utilice un instrumento afilado para
evitar daños y arañazos:
lRoscas de la bujía
lAsientos de válvula
2. Inspeccionar:
lCulata
Arañazos/Daños ® Reempla-
zar.
3. Medir:
lAlabeo de la culata
Fuera de especificaciones ®
Rectificar.
MONTAJE E INSTALACIÓN
1. Instalar:
lCulata
lPernos (1 ~ 4)
lPerno (5)
lTuercas (6, 7)
lTuercas (8, 9)
NOTA:
Siga el orden numérico establecido en la
ilustración. Apriete los pernos y las tuer-
cas en dos fases.
Alabeo de la culata:
Menos de 0,05 mm
(0,002 in)
Pasos de medición y rectificación
del alabeo:
lColoque una regla y un calibre de
espesores en la culata.
lUtilice un calibre de espesores para
medir el alabeo.
lSi el alabeo está fuera de especifi-
caciones, rectifique la culata.
lColoque un papel de lija húmedo
de grano 400 ~ 600 sobre el plano
de la junta de la culata y comience
el rectificado de la culata siguiendo
un patrón en forma de ocho.
NOTA:
Para asegurar una superficie uni-
forme, gire la culata varias veces.
T R..44 Nm (4,4 m · kg, 32 ft · lb)
T R..10 Nm (1,0 m · kg, 7,2 ft · lb)
T R..20 Nm (2,0 m · kg, 14 ft · lb)
T R..10 Nm (1,0 m · kg, 7,2 ft · lb)

4 - 33
ENG

VALVES AND VALVE SPRINGS
3. Inspect:
l
Valve face
Pitting/wear
®
Grind the face.
l
Valve stem end
Mushroom shape or diameter larger
than the body of the stem
®
Replace.
4. Measure:
l
Margin thickness
a

Out of specification
®
Replace.
5. Measure:
l
Runout (valve stem)
Out of specification
®
Replace.
NOTE:

l
When installing a new valve always replace
the guide.
l
If the valve is removed or replaced always
replace the oil seal.
6. Eliminate:
l
Carbon deposits
From the valve face and valve seat.
7. Inspect:
l
Valve seats
Pitting/wear
®
Reface the valve seat.
8. Measure:
l
Valve seat width
a

Out of specification
®
Reface the valve
seat.
Margin thickness:
Intake:
1.0 mm (0.039 in)
: 0.85 mm (0.033 in)
Exhaust:
1.0 mm (0.039 in)
: 0.85 mm (0.033 in)
Runout limit:
0.01 mm (0.0004 in)
Valve seat width:
Intake:
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
: 1.5 mm (0.06 in)
Exhaust:
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
: 1.5 mm (0.06 in)
NOTE:
After replacing the valve guide reface the
valve seat.

4 - 34
ENG

VALVES AND VALVE SPRINGS
Measurement steps:
l
Apply Mechanic’s blueing dye (Dykem)
b
to the valve face.
l
Install the valve into the cylinder head.
l
Press the valve through the valve guide
and onto the valve seat to make a clear
pattern.
l
Measure the valve seat width. Where the
valve seat and valve face made contact,
blueing will have been removed.
l
If the valve seat is too wide, too narrow, or
the seat is not centered, the valve seat
must be refaced.
9. Lap:
l
Valve face
l
Valve seat
NOTE:

After refacing the valve seat or replacing the
valve and valve guide, the valve seat and
valve face should be lapped.
Lapping steps:
l
Apply a coarse lapping compound to the
valve face.
l
Apply molybdenum disulfide oil to the
valve stem.
l
Install the valve into the cylinder head.
l
Turn the valve until the valve face and
valve seat are evenly polished, then clean
off all of the compound.
l
Apply a fine lapping compound to the
valve face and repeat the above steps.
CAUTION:
Do not let the compound enter the gap
between the valve stem and the guide.
NOTE:
For best lapping results, lightly tap the valve
seat while rotating the valve back and forth
between your hands.

4 - 36
ENGVALVES AND VALVE SPRINGS
Valve lifter
1. Inspect:
lValve lifter
Scratches/damage ® Replace both lift-
ers and cylinder head.
ASSEMBLY AND INSTALLATION
1. Apply:
lMolybdenum disulfide oil
Onto the valve stem and valve stem
seal.
2. Install:
lValves 1
lValve spring seats 2
lValve stem seals 3
lValve springs 4
lValve spring retainers 5
NOTE:
lMake sure that each valve is installed in its
original place, also referring to the embossed
mark as follows.
Intake (right/left): “5BE:”
Intake (middle): “5BE·”
Exhaust: “5BE”
lInstall the valve springs with the larger pitch
a facing upwards.
bSmaller pitch
3. Install:
lValve cotters
NOTE:
While compressing the valve spring with a
valve spring compressor 1 and attachment 2
install the valve cotters.
Valve spring compressor:
YM-04019/90890-04019
Attachment:
YM-04108/90890-04108
New

4 - 37
ENGVALVES AND VALVE SPRINGS
4. To secure the valve cotters onto the
valve stem, lightly tap the valve tip with a
piece of wood.
CAUTION:
Hitting the valve tip with excessive force
could damage the valve.
5. Install:
lAdjusting pad 1
lValve lifter 2
NOTE:
lLubricate the valve lifters and pads with
molybdenum disulfide oil.
lValve lifter must turn smoothly when rotated
with a finger.
lBe careful to reinstall valve lifters and pads
in their original place.

4 - 41
ENGCYLINDER AND PISTON
Piston ring
1. Measure:
lRing side clearance
Use a feeler gauge 1.
Out of specification ® Replace the pis-
ton and rings as a set.
NOTE:
Clean carbon from the piston ring grooves and
rings before measuring the side clearance.
2. Position:
lPiston ring
In cylinder.
NOTE:
Insert a ring into the cylinder and push it
approximately 10 mm (0.39 in) into the cylin-
der. Push the ring with the piston crown so that
the ring will be at a right angle to the cylinder
bore.
a10 mm (0.39 in)
3. Measure:
lRing end gap
Out of specification ® Replace.
NOTE:
You cannot measure the end gap on the
expander spacer of the oil control ring. If the oil
control ring rails show excessive gap, replace
all three rings.
Side clearance
Standard
Top
ring0.030 ~ 0.065 mm
(0.0012 ~ 0.0026 in)0.13 mm
(0.005 in)
2nd
ring0.020 ~ 0.055 mm
(0.0008 ~ 0.0022 in)0.13 mm
(0.005 in)
End gap
Standard Limit
Top
ring0.20 ~ 0.35 mm
(0.008 ~ 0.014 in)0.7 mm
(0.028 in)
2nd
ring0.40 ~ 0.55 mm
(0.016 ~ 0.022 in)0.8 mm
(0.031 in)
Oil
ring0.20 ~ 0.50 mm
(0.01 ~ 0.02 in)—

4 - 42
ENGCYLINDER AND PISTON
Piston pin
1. Inspect:
lPiston pin
Blue discoloration/grooves ®
Replace, then inspect the lubrication
system.
2. Measure:
lPiston pin-to-piston clearance
Measurement steps:
lMeasure the outside diameter (piston pin)
a.
If out of specification, replace the piston
pin
Outside diameter (piston pin):
17.991 ~ 18.000 mm
(0.7083 ~ 0.7087 in)
lMeasure the inside diameter (piston) b.
Inside diameter (piston):
18.004 ~ 18.015 mm
(0.7088 ~ 0.7093 in)
lCalculate the piston pin-to-piston clear-
ance with the following formula.
Piston pin-to-piston clearance =
Inside diameter (piston) b –
Outside diameter (piston pin) a
lIf out of specification, replace the piston.
Piston pin-to-piston clearance:
0.004 ~ 0.024 mm
(0.00016 ~ 0.00094 in)
: 0.07 mm (0.003 in)
ASSEMBLY AND INSTALLATION
Piston
1. Install:
lPiston rings
Onto the piston.
NOTE:
lBe sure to install the piston rings so that the
manufacturer’s marks or numbers are
located on the upper side of the rings.
lLubricate the piston and piston rings liberally
with engine oil.