2001 YAMAHA YZ426F transmission

CHAPTER 4
ENGINE
SEAT, FUEL TANK AND
SIDE COVERS
.......................................... 4-1
EXHAUST PIPE AND SILENCER
............ 4-2
RADIATOR
............................................... 4-4
CARBURETOR
......................................... 4-7
CAMSHAFTS
.......................................... 4-19
CYLINDER HEAD
................................... 4-26
VALVES AND VALVE SPRINGS
........... 4-30
CYLINDER AND PISTON
....................... 4-39
CLUTCH
.................................................. 4-45
OIL FILTER, WATER PUMP AND
CRANKCASE COVER (RIGHT)
............. 4-52
BALANCER
............................................ 4-59
OIL PUMP
............................................... 4-62
KICK AXLE AND SHIFT SHAFT
............ 4-66
CDI MAGNETO
....................................... 4-73
ENGINE REMOVAL
................................ 4-77
CRANKCASE AND CRANKSHAFT
....... 4-82
TRANSMISSION, SHIFT CAM AND
SHIFT FORK
........................................... 4-91
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL
...... 5-1
FRONT BRAKE AND REAR BRAKE
.... 5-10
FRONT FORK
......................................... 5-27
HANDLEBAR
.......................................... 5-40
STEERING
.............................................. 5-45
SWINGARM
............................................ 5-50
REAR SHOCK ABSORBER
................... 5-57

GEN
INFODESCRIPTION
FAHRZEUGBESCHREIBUNG
ALLGEMEINE ANGABEN
FAHRZEUGBESCHREIBUNG
1Kupplungshebel
2Dekompressionshebel
3Handbremshebel
4Gasdrehgriff
5Kühlerverschlußdeckel
6Kraftstoffankverschluß
7Motoröl-Einfüllschraubverschluß/Tauchstab
8Motorstoppschalter “ENGINE STOP”
9Kickstarter
0Kraftstofftank
AKühler
BKühlmittel-Ablaßschraube
CFußbremshebel
DAuslaufschutzventil
EKraftstoffhahn
FKaltstarterknopf
GHeißstarterknopf (rot)
HAntriebskette
ILuftfilter
JSchalthebel
KTeleskopgabel
HINWEIS:
lLeichte Modell-Abweichungen möglich.
lÄnderungen an Design und technischen Daten
jederzeit vorbehalten.
RENSEIGNEMENTS
GENERAUX
DESCRIPTION
1Levier d’embrayage
2Levier de décompression
3Levier de frein avant
4Poignée d’accélérateur
5Bouchon de radiateur
6Bouchon de réservoir à essence
7Bouchon d’orifice de remplissage et jauge d’huile
8Bouton du coupe-circuit de sécurité “ENGINE STOP”
9Démarreur au pied
0Réservoir de carburant
ARadiateur
BBoulon de vidange du liquide de refroidissement
CPédale de frein arrière
DJoint de robinet
ERobinet à essence
FBouton de démarrage à froid
GBouton de démarrage à chaud (rouge)
HChaîne de transmission
IFiltre à air
JPédale de sélecteur
KFourche avant
N.B.:
lVotre machine diffère peut-être partiellement de
celles montrées sur ces photos.
lLa conception et les caractéristiques peuvent
êtres changées sans préavis.
1 - 1
1

1 - 10
GEN
INFO
CONTROL FUNCTIONS
EC150000
CONTROL FUNCTIONS
EC151000
“ENGINE STOP” BUTTON
The “ENGINE STOP” button 1 is located on
the left handlebar. Continue pushing the
“ENGINE STOP” button till the engine comes
to a stop.
EC152000
CLUTCH LEVER
The clutch lever 1 is located on the left han-
dlebar; it disengages or engages the clutch.
Pull the clutch lever to the handlebar to disen-
gage the clutch, and release the lever to
engage the clutch. The lever should be pulled
rapidly and released slowly for smooth starts.
EC153000
SHIFT PEDAL
The gear ratios of the constant-mesh 5 speed
transmission are ideally spaced. The gears
can be shifted by using the shift pedal 1 on
the left side of the engine.
EC154000
KICK STARTER
Rotate the kick starter 1 away from the
engine. Push the starter down lightly with your
foot until the gears engage, then kick smoothly
and forcefully to start the engine. This model
has a primary kick starter so the engine can be
started in any gear if the clutch is disengaged.
In normal practices, however, shift to neutral
before starting.
1

1 - 15
GEN
INFO
STARTING AND BREAK-IN
STARTING A COLD ENGINE
1. Inspect the coolant level.
2. Turn the fuel cock to “ON”.
3. Shift the transmission into neutral.
4. Fully open the cold starter knob.
5. Without pulling in the decompression
lever, slowly depress the kick starter until
the compression stroke is found. When
considerable resistance of the kick starter
is felt, the engine is on the compression
stroke. If the engine is on the exhaust
stroke, resistance will only be felt when
the kick starter is initially depressed, not
through the entire range of depression
(as when the engine is on the compres-
sion stroke); therefore, depress the kick
starter a few more times.
6. Pull the decompression lever to the han-
dlebar and depress the kick starter 10 ~
20˚.
7. Release the decompression lever and
return the kick starter to its original posi-
tion and then kick the kick starter.
WARNING
Do not open the throttle while kicking the
kick starter. Otherwise, the kick starter may
kick back.
8. Return the cold starter knob to its original
position and run the engine at 3,000 ~
5,000 r/min for 1 or 2 minutes.
NOTE:
Since this model is equipped with an accelera-
tor pump, if the engine is raced (the throttle
opened and closed), the air/fuel mixture will be
too rich and the engine may stall. Also unlike a
two-stroke engine, this model can idle.
CAUTION:
Do not warm up the engine for extended
periods of time.

1 - 19
GEN
INFO
CLEANING AND STORAGE
EC1B0000
CLEANING AND STORAGE
EC1B1000
CLEANING
Frequent cleaning of your machine will
enhance its appearance, maintain good over-
all performance, 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
garden hose; use only enough pressure
to do the job.
CAUTION:
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
cleaner to keep the cover pliable and
glossy.

GEN
INFO

NETTOYAGE ET RANGEMENT
REINIGUNG UND STILLEGUNG
REINIGUNG UND STILLEGUNG
REINIGUNG
Eine regelmäßige, gründliche Wäsche sorgt nicht
nur für gutes Aussehen, sondern verbessert auch
das allgemeine Betriebsverhalten, reduziert Ver-
schleiß und bewirkt somit eine längere Lebens-
dauer und besseren Werterhalt.
1. Vor der Wäsche eine Plastiktüte über die
Schalldämpferöffnung stülpen und mit ei-
nem Gummiband sichern, damit kein
Wasser eindringen kann.
2. Bei stark veröltem Motor mit einem Pin-
sel Kaltreiniger auftragen. Jedoch keinen
Kaltreiniger auf Antriebskette, Kettenrä-
der und Radachsen bringen.
3. Schmutz und Kaltreiniger mit einem Was-
serschlauch gründlich abspülen. Dabei
den Wasserdruck möglichst gering halten.
ACHTUNG:

Durch zu hohen Wasserdruck können Wasser
und Verunreinigungen in Radlager, Teleskop-
gabel, Schwingenlager, Bremsen, Getriebe-
dichtungen und elektrische Komponenten
eindringen. Viele teure Reparaturen sind die
Folge falscher Anwendung von Hochdruckrei-
nigern (Dampfstrahler), wie sie z. B. bei Münz-
waschanlagen zu finden sind.
4. Nach dem Abspülen des groben Schmut-
zes alle Oberflächen mit warmem Wasser
und einem milden Reinigungsmittel abwa-
schen. Schwer zugängliche Stellen lassen
sich am besten mit einer alten Zahnbürste
oder einer Flaschenbürste reinigen.
5. Unmittelbar danach das Fahrzeug mit sau-
berem Wasser abspülen und mit einem
Waschleder, sauberen Tuch oder weichen,
saugfähigen Lappen abtrocknen.
6. Die Kette trocknen und sofort schmieren,
um Korrosion zu verhindern.
7. Die Sitzbank mit einem Reiniger für
Vinylpolster abwischen, damit der Bezug
geschmeidig und glänzend bleibt.
NETTOYAGE ET RANGEMENT
NETTOYAGE
Un nettoyage fréquent de la machine améliorera
son aspect, maintiendra ses bonnes performances et
augmentera la durée de service de bon nombre de
ses composants.
1. Avant de laver la moto, boucher la sortie du
pot d’échappement pour éviter toute pénétra-
tion d’eau. Un sachet en plastique retenu par
un élastique fera l’affaire.
2. Si le moteur est fortement encrassé, appliquer
un peu de dégraissant au pinceau. Eviter tout
contact avec la chaîne, ses pignons et les axes
de roue.
3. Rincer la boue et le dégraissant avec un tuyau
d’arrosage, en utilisant juste la pression suffi-
sante.
ATTENTION:

Une pression excessive risque de provoquer des
infiltrations d’eau dans les roulements des
roues, la fourche avant, des freins et les joints de
la transmission. Noter que bien des notes de
réparation onéreuses ont résulté de l’emploi
abusif des vaporisateurs de détergent à haute
pression, tels que ceux qui équipent les laveries
automatiques de voitures.
4. Après avoir chassé la majeure partie de la
boue, laver toutes les surfaces avec de l’eau
chaude et un détergent neutre. Utiliser une
vieille brosse à dents pour atteindre les
endroits difficiles d’accès.
5. Rincer immédiatement l’engin avec de l’eau
propre et sécher toutes les surfaces avec un
chiffon doux.
6. Immédiatement après le lavage, éliminer
l’excès d’eau de la chaîne avec des mou-
choirs en papier et lubrifier la chaîne pour
éviter qu’elle ne rouille.
7. Nettoyer la selle avec un produit pour meu-
bles rembourrés pour que sa housse reste sou-
ple et brillante.
1 - 19

SPEC

2 - 2
GENERAL SPECIFICATIONS
Oil capacity:
Engine oil
Periodic oil change 1.5 L (1.32 Imp qt, 1.59 US qt)
With oil filter replacement 1.6 L (1.41 Imp qt, 1.69 US qt)
Total amount 1.7 L (1.50 Imp qt, 1.80 US qt)
Coolant capacity (including all routes): 1.2 L (1.06 Imp qt, 1.27 US qt)
Air filter: Wet type element
Fuel:
Type Premium unleaded fuel with a research octane
number of 95 or higher. (Except for AUS)
Unleaded fuel only (For AUS)
Tank capacity 8.0 L (1.76 Imp gal, 2.11 US gal)
Carburetor:
Type FCR MX39
Manufacturer KEIHIN
Spark plug:
Type / manufacturer CR8E / NGK
U24ESR-N / DENSO
Gap 0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
Clutch type: Wet, multiple-disc
Transmission: USA, CDN, ZA,
AUS, NZEUROPE
Primary reduction system Gear
¬
Primary reduction ratio 62/21 (2.952)
¬
Secondary reduction system Chain drive
¬
Secondary reduction ratio 49/14 (3.500) 48/14 (3.429)
Transmission type Constant mesh,
5-speed
¬
Operation Left foot operation
¬
Gear ratio: 1st 24/13 (1.846)
¬
2nd 23/15 (1.533)
¬
3rd 23/18 (1.278)
¬
4th 24/22 (1.091)
¬
5th 20/21 (0.952)
¬
Chassis:
Frame type Semi double cradle
Caster angle 27.8˚
Trail 123 mm (4.84 in)
Tire:
Type With tube
Size (front) 80/100-21 51M (For USA, CDN, ZA, AUS, NZ
and F)
80/100-21 51R (For EUROPE except F)
Size (rear) 110/90-19 62M (For USA, CDN, ZA, AUS, NZ
and F)
110/90-19 NHS (For EUROPE except F)
Tire pressure (front and rear) 100 kPa (1.0 kg/cm
2

, 15 psi)

2

SPEC

2 - 10
MAINTENANCE SPECIFICATIONS
Item Standard
Lubrication chart:
Pressure feed
Splashed scavenge
Oil strainer
Oil pan Oil pump rotor 2
Oil pump rotor 1
Oil tank
Oil filter
Check ball
Cylinder head
Crank pinPiston pinPiston
Drive axleMain axleTransmission gears
Camshaft
Valve lifter