2000 YAMAHA YZ426F torque

2 - 18
SPEC

GENERAL TORQUE SPECIFICATIONS/
DEFINITION OF UNITS
EC220001
GENERAL TORQUE SPECIFICATIONS
This chart specifies torque for standard fasten-
ers with standard I.S.O. pitch threads. Torque
specifications for special components or
assemblies are included in the applicable sec-
tions of this book. To avoid warpage, tighten
multi-fastener assemblies in a crisscross fash-
ion, in progressive stages, until full torque is
reached. Unless otherwise specified, torque
specifications call for clean, dry threads. Com-
ponents should be at room temperature.
A
(Nut)B
(Bolt)TORQUE SPECIFICA-
TION
Nm m•kg ft•lb
10 mm
12 mm
14 mm
17 mm
19 mm
22 mm6 mm
8 mm
10 mm
12 mm
14 mm
16 mm6
15
30
55
85
1300.6
1.5
3.0
5.5
8.5
134.3
11
22
40
61
94
A: Distance between flats
B: Outside thread diameter
EC230000
DEFINITION OF UNITS
Unit Read Definition Measure
mm
cmmillimeter
centimeter10
-3

meter
10
-2

meterLength
Length
kg kilogram 10
3

gram Weight
N Newton 1 kg
´
m/sec
2

Force
Nm
m • kgNewton meter
Meter kilogramN
´
m
m
´
kgTorque
Torque
Pa Pascal N/m
2

Pressure
N/mm Newton per millimeter N/mm Spring rate
L
cm
3

Liter
Cubic centimeter—
—Volume or capacity
Volume or capacity
r/min Revolution per minute — Engine speed

3 - 43
INSP
ADJ
STEERING HEAD INSPECTION AND ADJUSTMENT
lTighten the ring nut 3 using ring nut
wrench 4.
Ring nut wrench:
YM-33975/90890-01403
T R..
Ring nut (initial tightening):
38 Nm (3.8 m • kg, 27 ft • lb)
lLoosen the ring nut one turn.
lRetighten the ring nut using the ring nut
wrench.
T R..
Ring nut (final tightening):
7 Nm (0.7 m • kg, 5.1 ft • lb)
lCheck the steering shaft by turning it lock
to lock. If there is any binding, remove the
steering shaft assembly and inspect the
steering bearings.
lInstall the handle crown 5, steering shaft
nut 6, handlebar 7, handlebar holder 8
and number plate 9.
T R..
Steering shaft nut:
145 Nm (14.5 m • kg, 105 ft • lb)
Handlebar upper holder:
23 Nm (2.3 m • kg, 17 ft • lb)
Pinch bolt (handle crown):
23 Nm (2.3 m • kg, 17 ft • lb)
NOTE:
Set the torque wrench to the ring nut
wrench so that they form a right angle.
WARNING
Avoid over-tightening.
NOTE:
lThe upper handlebar holder should be
installed with the punched mark a for-
ward.
lInsert the end of fuel breather hose 0 into
the hole of the number plate.
CAUTION:
First tighten the bolts on the front side of
the handlebar holder, and then tighten
the bolts on the rear side.

4 - 13
ENG
CARBURATEUR
VERGASER
Choke-Schieber
1. Kontrollieren:
lKaltstarter-Tauchkolben 1
lHeißstarter-Tauchkolben (rot) 2
Verschleiß/Beschädigung ® Erneuern.
Beschleunigungspumpe
1. Kontrollieren:
lMembran (Beschleunigungspumpe) 1
lFeder 2
lDeckel 3
lO-Ring 4
Rißbildung (Membran)/Beschädigung ®
Erneuern.
Schmutz ® Säubern.
ZUSAMMENBAU UND MONTAGE
Vergaser
1. Montieren:
lHeißstarter-Tauchkolben (rot) 1
lKaltstarter-Tauchkolben 2
2. Montieren:
lHauptluftdüse 1
lLeerlaufluftdüse 2
lAnsaugstutzen 3
3. Montieren:
lChoke-Düse 1
lLeerlaufdüse 2
lDistanzstück 3
lNadeldüse 4
lHauptdüse 5 Plongeur de starter
1. Contrôler:
lPlongeur de démarrage à froid 1
lPlongeur de démarrage à chaud (rouge) 2
Usure/endommagement ® Remplacer.
Pompe d’accélérateur
1. Contrôler:
lDiaphragme (pompe d’accélérateur) 1
lRessort 2
lCouvercle 3
lJoint torque 4
Déchirure (diaphragme)/endommagement
® Remplacer.
Sale ® Nettoyer.
ASSEMBLAGE ET MONTAGE
Carburateur
1. Monter:
lPlongeur de démarrage à chaud (rouge) 1
lPlongeur de démarrage à froid 2
2. Monter:
lGicleur d’air principal 1
lGicleur d’air de ralenti 2
lRaccord d’admission 3
3. Monter:
lGicleur de starter 1
lGicleur de ralenti 2
lEntretoise 3
lPuits d’aiguille 4
lGicleur principal 5

4 - 23
ENG

CAMSHAFTS
2. Install:
l
Timing chain tensioner
3. Turn:
l
Crankshaft
Counterclockwise several turns
4. Check:
l
Rotor “I” mark
Align with the crankcase stationary
pointer.
l
Camshaft match marks
Align with the cylinder head surface.
Out of alignment
®
Adjust.
.
l
Install the dowel pins, clips and camshaft
caps
4
.
T R..

Bolt (camshaft cap):
10 Nm (1.0 m • kg, 7.2 ft • lb)
.
Installation steps:
l
While pressing the tensioner rod lightly with
fingers, use a thin screwdriver and wind the
tensioner rod up fully clockwise.
l
With the rod fully wound and the chain ten-
sioner UP mark
a
facing upward, install the
gasket
1
and the chain tensioner
2
, and
tighten the bolt
3
to the specified torque.
T R..

Bolt (timing chain tensioner):
10 Nm (1.0 m • kg, 7.2 ft • lb)
l
Release the screwdriver, check the ten-
sioner rod to come out and tighten the
gasket
4
and the cap bolt
5
to the speci-
fied torque.
T R..

Tensioner cap bolt:
7 Nm (0.7 m • kg, 5.1 ft • lb)
CAUTION:
Do not turn the crankshaft during the
camshaft installation. Damage or
improper valve timing will result.
NOTE:
Tighten the bolts (camshaft cap) 5 in a
crisscross pattern.
CAUTION:
The bolts (camshaft cap) must be tightened
evenly or damage to the cylinder head,
camshaft caps and camshaft will result.

5 - 38
CHASFRONT FORK
26. Tighten:
lCap bolt (locknut) 1
NOTE:
lWhile compressing the fork spring, set the
thin type spanners 2 between the spacer 3
and spring guide 4.
lHold the locknut 5 and tighten the cap bolt
with specified torque.
T R..29 Nm (2.9 m · kg, 21 ft · lb)
27. Install:
lCap bolt 1
To outer tube.
NOTE:
Temporarily tighten the cap bolt.
28. Install:
lProtector guide 1
EC5552A0
Installation
1. Install:
lFront fork 1
NOTE:
lTemporarily tighten the pinch bolts (under
bracket).
lDo not tighten the pinch bolts (handle crown)
yet.
2. Tighten:
lCap bolt 1
3. Adjust:
lFront fork top end a
Front fork top end (standard) a:
Zero mm (Zero in)
T R..30 Nm (3.0 m · kg, 22 ft · lb)

5 - 39
CHASFRONT FORK
4. Tighten:
lPinch bolt (handle crown) 1
lPinch bolt (under bracket) 2
ACHTUNG:CAUTION:
Tighten the under bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
5. Install:
lBrake hose holder 1
lCaliper 2
lBolt (caliper) 3
NOTE:
Fit the brake hose holder cut a over the pro-
jection b on the front fork and clamp the brake
hose.
6. Install:
lBrake hose holder 1
lBolt (brake hose holder) 2
lProtector 3
lBolt (protector) 4
NOTE:
When installing the brake hose holder, pass
the brake hose 5 in front of the axle boss a,
then fit it into the hose groove b so that the
brake hose does not contact the nut (wheel
axle).
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..20 Nm (2.0 m · kg, 14 ft · lb)
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
T R..10 Nm (1.0 m · kg, 7.2 ft · lb)
7. Adjust:
lRebound damping force
NOTE:
Turn in the damping adjuster 1 finger-tight
and then turn out to the originally set position.

5 - 49
CHASSTEERING
9. After tightening the nut, check the steer-
ing for smooth movement. If not, adjust
the steering by loosening the ring nut little
by little.
10. Adjust:
lFront fork top end a
Front fork top end (standard) a:
Zero mm (Zero in)
11. Tighten:
lPinch bolt (handle crown) 1
lPinch bolt (under bracket) 2
ACHTUNG:CAUTION:
Tighten the under bracket to specified
torque. If torqued too much, it may cause
the front fork to malfunction.
T R..23 Nm (2.3 m · kg, 17 ft · lb)
T R..20 Nm (2.0 m · kg, 14 ft · lb)

7 - 20
TUNSETTING
EC72H002
Suspension setting
lFront fork
NOTE:
lIf any of the following symptoms is experienced with the standard position as the base, make
resetting by reference to the adjustment procedure given in the same chart.
lBefore any change, set the rear shock absorber sunken length to the standard figure 90 ~
100 mm (3.5 ~ 3.9 in).
SymptomSection
Check Adjust
JumpLarge
gapMedium
gapSmall
gap
Stiff over entire range
CCC
Compression damping
Oil level (oil amount)
SpringTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with soft spring.
Unsmooth movement
over entire range
CCCC
Outer tube
Inner tube
Under bracket tightening
torqueCheck for any bends, dents, and other noticeable
scars, etc. If any, replace affected parts.
Retighten to specified torque.
Poor initial
movement
C
Rebound damping
Oil sealTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Apply grease in oil seal wall.
Soft over entire range,
bottoming out
CC
Compression damping
Oil level (oil amount)
SpringTurn adjuster clockwise (about 2 clicks) to increase
damping.
Increase oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).
Replace with stiff spring.
Stiff toward stroke end
COil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
Soft toward stroke end,
bottoming out
COil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Stiff initial movement
CCCCCompression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front posture
CC
Compression damping
Rebound damping
Balance with rear end
Oil level (oil amount)Turn adjuster clockwise (about 2 clicks) to increase
damping.
Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 95 ~ 100 mm (3.7 ~ 3.9 in) when
one passenger is astride seat (lower rear posture).
Increase oil level by about 5 mm (0.2 in).
“Obtrusive” front, tend-
ing to upper front pos-
ture
CC
Compression damping
Balance with rear end
Spring
Oil lever (oil amount)Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Set sunken length for 90 ~ 95 mm (3.5 ~ 3.7 in) when
one passenger is astride seat (upper rear posture).
Replace with soft spring.
Decrease oil level by about 5 ~ 10 mm (0.2 ~ 0.4 in).