2008 YAMAHA WR 450F torque

2-18
TIGHTENING TORQUES
GENERAL TORQUE
SPECIFICATIONS
This chart specifies torque for stan-
dard fasteners with standard I.S.O.
pitch threads. Torque specifications
for special components or assem-
blies are included in the applicable
sections of this book. To avoid
warpage, tighten multi-fastener as-
semblies in a crisscross fashion, in
progressive stages, until full torque is
reached. Unless otherwise specified,
torque specifications call for clean,
dry threads. Components should be
at room temperature.A. Distance between flats
B. Outside thread diameter
DEFINITION OF UNITS
A
(Nut)B
(Bolt
)TORQUE SPECIFI-
CATION
Nm m•kg ft•lb
10
mm6 mm 6 0.6 4.3
12
mm8 mm 15 1.5 11
14
mm10
mm30 3.0 22
17
mm12
mm55 5.5 40
19
mm14
mm85 8.5 61
22
mm16
mm130 13 94
Unit Read Definition Measure
mm
millimeter 10-3 meter Length
cmcentimeter 10-2 meter Length
kgkilogram 103 gram Weight
NNewton 1 kg × m/sec2Force
NmNewton meter N × m Torque
m•kgMeter kilogram m × kg Torque
PaPascal N/m2Pressure
N/mmNewton per millimeter N/mm Spring rate
LLiter — Volume or capacity
cm3Cubic centimeter — Volume or capacity
r/minRevolution per minute — Engine speed

3-24
CHASSIS
CHECKING THE TIRE PRESSURE
1. Measure:
• Tire pressure
Out of specification→Adjust.
• Check the tire while it is cold.
• Loose bead stoppers allow the tire
to slip off its position on the rim
when the tire pressure is low.
• A tilted tire valve stem indicates that
the tire slips off its position on the
rim.
• If the tire valve stem is found tilted,
the tire is considered to be slipping
off its position. Correct the tire posi-
tion.
CHECKING AND TIGHTENING THE
SPOKES
1. Inspect:
• Spokes "1"
Bend/damage→Replace.
Loose spoke→Retighten.
2. Tighten:
• Spokes
Be sure to retighten these spokes be-
fore and after break-in. After a prac-
tice or a race check spokes for
looseness.
CHECKING THE WHEELS
1. Inspect:
• Wheel runout
Elevate the wheel and turn it.
Abnormal runout→ Replace.
2. Inspect:
• Bearing free play
Exist play→Replace.
CHECKING AND ADJUSTING THE
STEERING HEAD
1. Elevate the front wheel by placing
a suitable stand under the engine.
2. Check:
• Steering stem
Grasp the bottom of the forks and
gently rock the fork assembly
back and forth.
Free play→Adjust steering head.
3. Check:
• Steering smooth action
Turn the handlebar lock to lock.
Unsmooth action→Adjust steer-
ing ring nut.
4. Adjust:
• Steering ring nut
Steering ring nut adjustment
steps:
a. Remove the headlight.
b. Remove the handlebar and upper
bracket.c. Loosen the steering ring nut "1"
using the steering nut wrench "2".
d. Tighten the steering ring nut "3"
using steering nut wrench "4".
• Apply the lithium soap base grease
on the thread of the steering stem.
• Set the torque wrench to the steer-
ing nut wrench so that they form a
right angle.
e. Loosen the steering ring nut one
turn.
f. Retighten the steering ring nut us-
ing the steering nut wrench.
Avoid over-tightening.
g. Check the steering stem by turn-
ing it lock to lock. If there is any
binding, remove the steering stem
assembly and inspect the steer-
ing bearings.
h. Install the washer "5", upper
bracket "6", washer "7", steering
stem nut "8", handlebar "9", han-
dlebar upper holder "10" and
headlight "11". Standard tire pressure:
100 kPa (1.0 kgf/cm
2,
15 psi)
Spokes:
3 Nm (0.3 m•kg, 2.2
ft•lb)
Steering nut wrench:
YU-33975/90890-01403
Steering nut wrench:
YU-33975/90890-01403
Steering ring nut (initial
tightening):
38 Nm (3.8 m•kg, 27
ft•lb)
Steering ring nut (final
tightening):
7 Nm (0.7 m•kg, 5.1
ft•lb)

4-8
CHASSIS
SUSPENSION SETTING (FRONT FORK)
• If 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.
• Before 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
gapMedi-
um
gapSmall
gap
Stiff over entire
range○○○Compression damping Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Oil level (oil amount) Decrease oil level by about 5–10 mm (0.2–0.4 in).
Spring Replace with soft spring.
Unsmooth move-
ment over entire
range○○○○Outer tube Check for any bends, dents, and other noticeable
scars, etc. If any, replace affected parts.
Inner tube
Under bracket tighten-
ing torqueRetighten to specified torque.
Poor initial move-
ment○Rebound damping Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Oil seal Apply grease in oil seal wall.
Soft over entire
range, bottoming
out○○Compression damping Turn adjuster clockwise (about 2 clicks) to in-
crease damping.
Oil level (oil amount) Increase oil level by about 5–10 mm (0.2–0.4 in).
Spring Replace with stiff spring.
Stiff toward stroke
end○Oil level (oil amount) Decrease oil level by about 5 mm (0.2 in).
Soft toward stroke
end, bottoming out○Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
Stiff initial move-
ment○○○○Compression dampingTurn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Low front, tending to
lower front posture○○Compression damping Turn adjuster clockwise (about 2 clicks) to in-
crease damping.
Rebound damping Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Balance with rear end Set sunken length for 95–100 mm (3.7–3.9 in)
when one passenger is astride seat (lower rear
posture).
Oil level (oil amount) Increase oil level by about 5 mm (0.2 in).
"Obtrusive" front,
tending to upper
front posture○○Compression damping Turn adjuster counterclockwise (about 2 clicks) to
decrease damping.
Balance with rear end Set sunken length for 90–95 mm (3.5–3.7 in)
when one passenger is astride seat (upper rear
posture).
Spring Replace with soft spring.
Oil level (oil amount) Decrease oil level by about 5–10 mm (0.2–0.4 in).

5-19
CAMSHAFTS
Do not turn the crankshaft during
the camshaft installation. Damage
or improper valve timing will re-
sult.
d. Install the clips, camshaft caps "4"
and bolts (camshaft cap) "5".
• Before removing the clips, cover the
cylinder head with a clean rag to
prevent the clips from into the cylin-
der head cavity.
• Apply the molybdenum disulfide oil
on the thread of the bolts (camshaft
cap).
• Tighten the bolts to the specified
torque in two or three steps in the
proper tightening sequence as
shown.
The bolts (camshaft cap) must be
tightened evenly, or damage to the
cylinder head, camshaft caps, and
camshaft will result.
2. Install:
• Timing chain tensioner
Installation steps:
a. While pressing the tensioner rod
lightly with fingers, use a thin
screwdriver and wind the tension-
er rod up fully clockwise.
b. With the rod fully wound and the
chain tensioner UP mark "a" fac-
ing upward, install the gasket "1",
the timing chain tensioner "2", and
the gasket "3", and tighten the bolt
"4" to the specified torque.
c. Release the screwdriver, check
the tensioner rod to come out and
tighten the gasket "5" and the cap
bolt "6" to the specified torque.
3. Turn:
• Crankshaft
Counterclockwise several turns.4. Check:
• Rotor T.D.C. mark
Align with the crankcase align
mark.
• Camshaft match marks
Align with the cylinder head sur-
face.
Out of alignment→Adjust.
Bolt (camshaft cap):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (timing chain ten-
sioner):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Tensioner cap bolt:
7 Nm (0.7 m•kg, 5.1
ft•lb)

5-21
CYLINDER HEAD
CHECKING THE CYLINDER HEAD
1. Eliminate:
• Carbon deposits (from the com-
bustion chambers)
Use a rounded scraper.
Do not use a sharp instrument to
avoid damaging or scratching:
• Spark plug threads
• Valve seats
2. Inspect:
• Cylinder head
Scratches/damage→Replace.
3. Measure:
• Cylinder head warpage
Out of specification→Resurface.
Warpage measurement and resur-
facing steps:
a. Place a straightedge and a feeler
gauge across the cylinder head.
b. Use a feeler gauge to measure
the warpage.
c. If the warpage is out of specifica-
tion, resurface the cylinder head.
d. Place a 400–600 grit wet sandpa-
per on the surface plate, and re-
surface the head using a figure-
eight sanding pattern.
To ensure an even surface rotate the
cylinder head several times.
INSTALLING THE CYLINDER
HEAD
1. Install:
• Timing chain guide (exhaust side)
"1"
• Dowel pin "2"
• Cylinder head gasket "3" • Cylinder head "4"
While pulling up the timing chain, in-
stall the timing chain guide (exhaust
side) and cylinder head.
2. Install:
• Washer "1"
• Bolts "2"
Installation steps:
Tighten the cylinder head using
the rotation angle procedure to ob-
tain uniform tightening torque.
a. Wash the threads and contact
surfaces of the bolts, the contact
surfaces of the plain washers, the
contact surface of the cylinder
head, and the threads of the
crankcase.
b. Apply the molybdenum disulfide
grease on the threads and con-
tact surfaces of the bolts and on
both contact surfaces of the plain
washers.
c. Install the plain washers and
bolts.
d. Tighten the bolts to the specified
torque in two or three steps in the
proper tightening sequence as
shown.e. Remove the bolts.
f. Again apply the molybdenum dis-
ulfide grease on the threads and
contact surfaces of the bolts and
on both contact surfaces of the
plain washers.
g. Retighten the bolts.
Tighten the bolts to the specified
torque in two or three steps in the
proper tightening sequence as
shown.
h. Put a mark on the corner "1" of the
bolt (cylinder head) and the cylin-
der head "2" as shown.
Tighten the bolts 90° in each of the
two steps to reach the specified angle
of 180° in the proper tightening se-
quence as shown.
Cylinder head warpage:
Less than 0.05 mm
(0.002 in)
Bolts (cylinder head):
1st:
30 Nm (3.0 m•kg, 22
ft•lb)
Bolts (cylinder head):
2nd:
20 Nm (2.0 m•kg, 14
ft•lb)
Bolts (cylinder head):
Final:
Specified angle 180°

5-48
AC MAGNETO AND STARTER CLUTCH
AC MAGNETO AND STARTER CLUTCH
REMOVING THE AC MAGNETO AND STARTER CLUTCH
Order Part name Q'ty Remarks
Drain the engine oil.Refer to "CHANGING THE ENGINE OIL"
section in the CHAPTER 3.
Seat and fuel tankRefer to "REMOVING THE SEAT, FUEL
TANK AND SIDE COVERS" section in the
CHAPTER 3.
Disconnect the AC magneto lead.
1 Shift pedal 1
2 Cover (torque limiter) 1
3 Torque limiter 1 Do not disassemble.
4 Crankcase cover (left) 1
5 Gasket 1
6 Dowel pin 2
7 Idle gear 1
8 Bearing 1
9Shaft 1
10* Nut (rotor) 1 Refer to NOTE.
11 Rotor 1 Refer to removal section.

5-50
AC MAGNETO AND STARTER CLUTCH
REMOVING THE ROTOR
1. Remove:
• Nut (rotor) "1"
• Washer
Use the sheave holder "2".
2. Remove:
• Rotor "1"
Use the rotor puller "2".
REMOVING THE STARTER
CLUTCH
1. Remove:
• Starter clutch assembly cover "1"
Insert a thin screwdriver or the like
under the convexity "a" and remove
the starter clutch assembly cover by
prying it gently to void damage to the
cover.
2. Remove:
• Starter clutch "1"
Using a thin screwdriver or the like,
remove the plate "a" while prying it
upward little by little.
CHECKING THE AC MAGNETO
1. Inspect:
• Rotor inner surface "a"
• Stator outer surface "b"
Damage→Inspect the crankshaft
runout and crankshaft bearing.
If necessary, replace AC magneto
and/or stator.
CHECKING THE WOODRUFF KEY
1. Inspect:
• Woodruff key "1"
Damage→Replace.
CHECKING THE STARTER
CLUTCH
1. Check:
• Starter clutch
Damage/wear→Replace.
2. Check:
• Idle gear
• Idle gear shaft
• Starter clutch drive gear
Pitting/burrs/chips/roughness/
wear→Replace the defective
parts.
3. Check:
• Starter clutch operation
a. Install the starter clutch drive gear
"1" onto the starter clutch "2" and
hold the starter clutch.b. When turning the starter clutch
drive gear counterclockwise "B",
the starter clutch and the starter
clutch drive gear should engage.
If the starter clutch drive gear and
starter clutch do not engage, the
starter clutch is faulty and must be
replaced.
c. When turning the starter clutch
drive gear clockwise "A", it should
turn freely. If the starter clutch
drive gear does not turn freely, the
starter clutch is faulty and must be
replaced.
CHECKING THE TORQUE LIMITER
1. Check:
• Torque limiter
Damage/wear→Replace.
INSTALLING THE AC MAGNETO
AND STARTER CLUTCH
1. Install:
• Stator "1"
• Bolt (stator) "2"
• Pickup coil "3"
• Holder "4"
• Bolt (pickup coil) "5" Sheave holder:
YS-1880-A/90890-
01701
Rotor puller:
YM-04142/90890-04142
Bolt (stator):
7 Nm (0.7 m•kg, 5.1
ft•lb)
Bolt (pickup coil):
10 Nm (1.0 m•kg, 7.2
ft•lb)

5-51
AC MAGNETO AND STARTER CLUTCH
• Pass the AC magneto lead "5" un-
der the pickup coil.
• Pass the AC magneto lead "4" un-
der the holder as shown.
• Take care not to catch the AC mag-
neto lead between crankcase cover
ribs.
• Tighten the bolt (stator) using the
T25 bit.
• Apply the sealant to the grommet of
the AC magneto lead.
2. Install:
• Starter clutch drive gear "1"
Apply the engine oil on the starter
clutch drive gear inner circumference.
3. Install:
• Starter clutch "1"
To rotor "2".
• Install the starter clutch with its
plate side upward.
• While installing the starter clutch,
push in the projections "a" one by
one on the clutch circumference.
• Push in the starter clutch until it hits
the rotor.
4. Install:
• Starter clutch assembly cover "1"
To rotor "2".
Install the starter clutch assembly
cover by fitting its pawls "a" into the
groove "b" in the rotor.
5. Install:
• Woodruff key "1"
• Rotor "2"
• Degrease the contact surfaces of
the tapered portions of the crank-
shaft and rotor.
• When installing the woodruff key,
make sure that its flat surface "a" is
in parallel with the crankshaft center
line "b".
• When installing the rotor, align the
keyway "c" of the rotor with the
woodruff key.
6. Install:
• Washer (rotor)
• Nut (rotor) "1"
Use the sheave holder "2"
Tighten the rotor nut to 65 Nm (6.5
m•kg, 47 ft•lb), loosen and retighten
the rotor nut to 65 Nm (6.5 m•kg, 47
ft•lb).
7. Install:
• Shaft "1"
• Bearing "2"
• Idle gear 2 "3"
Apply the engine oil on the shaft,
bearing and idle gear inner circumfer-
ence.
8. Install:
• Dowel pin
• Gasket [crankcase cover (left)]
• Crankcase cover (left) "1"
• Bolt [crankcase cover (left)]
Tighten the bolts in stage, using a
crisscross pattern.
9. Install:
• Washer "1"
• Torque limiter "2"
• Washer
Apply the engine oil to the shaft and
washers.
10. Install:
• Cover (idle gear 1) "1"
•Bolt "2" YAMAHA Bond No. 1215
(ThreeBond
® No. 1215):
90890-85505
Nut (rotor):
65 Nm (6.5 m•kg, 47
ft•lb)
Sheave holder:
YS-1880-A/90890-
01701
Bolt [crankcase cover
(left)]:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)