2000 YAMAHA YZ426F engine

2 - 21
SPEC

CABLE ROUTING DIAGRAM
EC240000
CABLE ROUTING DIAGRAM
1
Hose guide
2
Brake hose
3
Fuel tank breather hose
4
Oil tank breather hose
5
Clamp
6
“ENGINE STOP” button lead
7
Sub wire harness
8
TPS (throttle position sensor)
lead
9
Neutral switch lead
0
Oil hose
A
Hose holder
B
CDI magneto lead
C
Clutch cable
D
Cylinder head breather hose
E
Carburetor breather hose
F
Overflow hose

Pass the clutch cable through
the cable guide.
õ
Pass the fuel tank breather
hose between the handlebar
and tension bar, then insert its
end into the hole of the num-
ber plate.
‚
Pass the decompression cable
and “ENGINE STOP” button
lead under the frame.
ë
Pass the “ENGINE STOP” but-
ton lead along the inner side of
the decompression cable.
ä
Fasten the CDI magneto lead,
neutral switch lead and
“ENGINE STOP” button lead
to the frame with a plastic lock-
ing tie and cut off the tie end.
ì
Pass the “ENGINE STOP”
button lead along the inner
side of the oil tank breather
hose.
í
Fasten the sub wire harness
and “ENGINE STOP” button
lead to the frame with a plas-
tic locking tie and cut off the
tie end.
î
Pass the cylinder head breather
hose along the right side of the
oil tank breather hose.
é
Fasten the sub wire harness to
the frame with a plastic locking
tie and cut off the tie end.
ï
Fasten the TPS lead (in the
sub wire harness) under the
frame.

SPEC

CHEMINEMENT DES CABLES
KABELFÜHRUNG
KABELFÜHRUNG
1
Kabelführung
2
Bremsschlauch
3
Kraftstofftank-Belüftungsschlauch
4
Öltank-Belüftungsschlauch
5Kabelbinder
6Motorstoppschalter-Kabel
7Nebenkabelsatz
8Drosselklappen-Positionssensor (TPS)
9Leerlaufschalter-Kabel
0Ölschlauch
ASchlauchhalterung
BCDI-Schwungradmagnetzünder-Kabel
CKupplungszug
DZylinderkopf-Entlüftungsschlauch
EVergaser-Entlüftungsschlauch
FAuslaufschutzschlauch
Den Kupplungszug durch die Kabelführung füh-
ren.
õDen Kraftstofftank-Belüftungsschlauch zwischen
Lenker und Zugstrebe führen und das Ende
durch die Bohrung im Nummerschild führen.
‚Den Dekompressionszug und das Motorstopp-
schalterkabel unter dem Rahmen hindurchfüh-
ren.
ëDas Motorstoppschalter-Kabel hinter dem De-
kompressionszug führen.
äDas CDI-Schwungrad-Magnetzünderkabel, Leer-
laufschalterkabel und Motorstoppschalterkabel
mit einem Einweg-Kabelbinder am Rahmen be-
festigen und das überstehende Ende des Kabel-
binders abschneiden.
ìDas Motorstoppschalter-Kabel hinter dem Öl-
tank-Belüftungsschlauch führen.
íDen Nebenkabelbaum und Motorstoppschalter-
kabel mit einem Einweg-Kabelbinder am Rah-
men befestigen und das überstehende Ende des
Kabelbinders abschneiden.
îDen Zylinderkopf-Entlüftungsschlauch rechts
vom Öltank-Belüftungsschlauch führen.
éDen Nebenkabelbaum mit einem Einweg-Kabel-
binder am Rahmen befestigen und das überste-
hende Ende des Kabelbinders abschneiden.
ïDas TPS-Kabel (im Nebenkabelbaum) unter
dem Rahmen befestigen.
CHEMINEMENT DES CABLES
1Guide de flexible
2Tuyau de frein
3Reniflard de réservoir d’essence
4Reniflard de réservoir d’huile
5Bride
6Fil de bouton d’arrêt du moteur “ENGINE STOP”
7Faisceau de fils secondaires
8Fil de TPS (copteur du papillon d’accélération)
9Fil de contacteur de point mort
0Flexible d’huile
ASupport de flexible
BFil de magnéto CDI
CCâble d’embrayage
DReniflard de culasse
EReniflard de carburateur
FFlexible de trop-plein
Faire passer le câble d’embrayage dans le guide de
câble.
õFaire passer le reniflard du réservoir d’essence entre
le guidon et la barre de tension, puis insérer son
extrémité dans l’orifice prévu sur la plaque de
numéro.
‚Faire passer le câble de décompression et le fil de
bouton d’arrêt du moteur “ENGINE STOP” sous le
cadre.
ëFaire passer le fil de bouton d’arrêt du moteur
“ENGINE STOP” derrière le câble de décompres-
sion.
äAttacher le fil de magnéto CDI, le fil de contacteur de
point mort et le fil de bouton d’arrêt du moteur
“ENGINE STOP” au cadre à l’aide d’une attache en
plastique et couper l’extrémité de l’attache.
ìFaire passer le fil de bouton d’arrêt du moteur
“ENGINE STOP” derrière le reniflard du réservoir
d’huile et couper l’extrémité de l’attache.
íAttacher le faisceau de fils secondaires et le fil de
bouton d’arrêt du moteur “ENGINE STOP” au cadre
à l’aide d’une attache en plastique et couper l’extré-
mité de l’attache.
îFaire passer le reniflard de culasse le long du côté
droit du reniflard du réservoir d’huile.
éAttacher le faisceau de fils secondaires au cadre à
l’aide d’une attache en plastique et couper l’extrémité
de l’attache.
ïAttacher le fil de TPS (dans le faisceau de fils secon-
daires) sous le cadre.
2 - 21

2 - 22
SPEC

CABLE ROUTING DIAGRAM
ð
Fasten the TPS lead under the
coupler to the frame with a plas-
tic locking tie.
ñPass the carburetor breather
hose and overflow hose
between the connecting rod and
cross tube (frame).
÷Fasten the neutral switch lead
and oil hose together with a
plastic locking tie and cut off the
tie end.
öFasten the cylinder head
breather hose and neutral switch
lead to the frame with a plastic
locking tie.
¯Fasten the neutral switch lead to
the frame with a plastic band.¸Fasten the cylinder head
breather hose with the hose
holder.
ÎPass the clutch cable through
the cable guide.
åFasten the neutral switch lead
and CDI magneto lead
together with a plastic band.
êPass the clutch cable on the
inside the cylinder head
breather hose.
æPass the cylinder head
breather hose along the inner
side of the radiator pipe.
èPass the radiator breather
hose from the right side of the
frame to the left side, over
radiator pipe 1, along the innerside of radiator hose 4 and
the radiator, and between the
lower engine bracket, crank-
case, oil hose and the frame.
×Pass the clutch cable
between the frame and radia-
tor and over the lower boss on
the radiator.
ãPass the neutral switch lead
and CDI magneto lead over
the middle radiator mounting
boss. Then, pass the decom-
pression cable under the mid-
dle radiator mounting boss
and along the left side of the
neutral switch lead and CDI
magneto lead.

2 - 25
SPECCABLE ROUTING DIAGRAM
1Throttle cable
2Clamp
3Decompression cable
4Clutch cable
5Brake hose
6Hose guide
7“ENGINE STOP” button leadFasten the “ENGINE STOP” button lead to the handlebar with the
plastic band.
õPass the brake hose in front of the number plate.

SPEC
CHEMINEMENT DES CABLES
KABELFÜHRUNG
1Gaszug
2Kabelbinder
3Dekompressionszug
4Kupplungszug
5Bremsschlauch
6Kabelführung
7Motorstoppschalter-Kabel
Das Motorstoppschalter-Kabel mit mehrf. ver-
wendb. Kabelbinder am Lenker befestigen.
õDen Bremsschlauch vor dem Nummernschild
führen. 1Câble d’accélération
2Bride
3Câble du décompresseur
4Câble d’embrayage
5Tuyau de frein
6Guide de flexible
7Fil de bouton d’arrêt du moteur “ENGINE STOP”
Fixer le fil de bouton d’arrêt du moteur “ENGINE
STOP” au guidon à l’aide d’une attache en plastique.
õFaire passer le tuyau de frein par-devant la plaque de
numéro.
2 - 25

3 - 1
INSP
ADJ

MAINTENANCE INTERVALS
EC300000
REGULAR INSPECTION AND ADJUSTMENTS
EC310022
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)Every
fifth
(or
1,000 km)
As re-
quiredRemarks
ENGINE OIL
Replace
cc
OIL FILTER
Replace
cc
VALVES
Check the valve clearances.
Inspect
Replace
cc
c
c
The engine must be cold.
Check the valve seats and
valve stems for wear.
VALVE SPRINGS
Inspect
Replace
c
c
Check the free length and
the tilt.
VALVE LIFTERS
Inspect
Replace
c
c
Check for scratches and
wear.
CAMSHAFTS
Inspect
Replace
c
c
Inspect the camshaft sur-
face.
CAMSHAFT SPROCKETS
Inspect
Replace
c
c
Check for wear on the
teeth and for damage.
PISTON
Inspect
Clean
Replace
cc
c
c
Inspect crack
Remove carbon
PISTON RING
Inspect
Replace
c
cc
Check ring end gap
PISTON PIN
Inspect
Replace
c
c
CYLINDER HEAD
Inspect and clean
Retighten
c
Remove carbon
Change gasket
CYLINDER
Inspect and clean
Replace
c
c
Inspect score marks
Inspect wear
CLUTCH
Inspect and adjust
Replace
cc
c
Inspect housing, friction
plate, clutch plate and
spring
TRANSMISSION
Inspect
Replace bearing
c
c
3

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.
EC321000
GENERAL INSPECTION AND MAINTENANCE
Item Routine Page
CoolantCheck that coolant is filled up to the radiator filler cap.
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.1-12
Engine oilCheck that the oil level is correct. Check the crankcase and
frame oil line for leakage.P.3-13 ~ 17
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-9
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.3-24 ~ 30
ChainCheck chain slack and alignment. Check that the chain is lubri-
cated properly.P.3-31 ~ 33
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-41 ~ 42
SteeringCheck that the handlebar can be turned smoothly and have no
excessive play.P.3-42 ~ 43
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage. P.3-33 ~ 40
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. P.4-3
Sprocket Check that the driven sprocket tightening bolt is not loose. P.3-31
Lubrication Check for smooth operation. Lubricate if necessary. P.3-44
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-17
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-5
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 ~ 21

3 - 5
INSP
ADJ

EC350000
ENGINE
EC351011
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. Remove:
l
Radiator cap
3. Check:
l
Coolant level
a

Coolant level low
®
Add coolant.
1
Radiator
ENGINE/COOLANT LEVEL INSPECTION