clutch YAMAHA YZ450F 2008 User Guide

2-19
CABLE ROUTING DIAGRAM
E. Pass the clutch cable in front of
the radiator mounting boss.
F. Install the connector cover so
that it does not come in between
the radiator hose 1 and radiator.
G. Pass the fuel hose between the
hot starter cable and throttle po-
sition sensor lead.
H. Pass the carburetor breather
hoses and overflow hose so that
all there hoses do not contact
the rear shock absorber.

2-20
CABLE ROUTING DIAGRAM
1. Hot starter cable
2. Clamp
3. Throttle position sensor lead
4. Hump (frame)
5. Neutral switch lead
6. Engine bracket
7. Lower engine guard stay
8. CDI magneto lead
9. Clutch cable
10. Radiator breather hose
11. Radiator hose 212. Engine stop switch lead
13. Sub-wire harness
14. Ground lead
15. CDI unit bracket
16. CDI unit
17. Cable guide
18. Ignition coil lead
19. Throttle cableA. Fasten the hot starter cable and
throttle cables onto the frame.
Locate the clamp ends under
the hot starter cable.
B. Fasten the hot starter cable,
throttle cables, throttle position
sensor lead and ignition coil lead
to the frame.
C. Pass the throttle position sensor
lead over the hot starter cable.

2-21
CABLE ROUTING DIAGRAM
D. Fasten the throttle position sen-
sor lead to the frame behind its
hump.
E. Pass the neutral switch lead on
the inside of the engine bracket.
F. Pass the neutral switch lead
over the lower engine guard
stay.
G. Fasten the neutral switch lead
and radiator breather hose to
the frame.
H. Fasten the neutral switch lead,
CDI magneto lead and radiator
breather hose to the frame.
I. Fasten the neutral switch lead,
CDI magneto lead, radiator
breather hose and clutch cable
to the frame over the radiator
mounting boss.
J. Pass the radiator breather hose
in front of the radiator hose 2, on
the left of the chassis, and then
between the frame and radiator
hose 4.
K. Fasten the sub-wire harness,
engine stop switch lead and
ground lead to the CDI unit
bracket at the position-taped
portion of the sub-wire harness
and with the clamp ends facing
downward.
L. Fasten the ground lead and ca-
ble guide together to the CDI
unit bracket.
M. Locate the clamp ends in the ar-
rowed range.
N. Fasten the neutral switch lead
and CDI magneto lead to the
frame over its hump.

2-24
CABLE ROUTING DIAGRAM
1. Throttle cable
2. Clamp
3. Hot starter cable
4. Clutch cable
5. Engine stop switch lead
6. Cable guide
7. Brake hose
8. Hose guide
A. Fasten the engine stop switch
lead to the handlebar.B. Pass the clutch cable and hot
starter cable through the cable
guide.
C. Pass the brake hose in front of
the number plate.
D. Pass the throttle cables through
the cable guide.
E. Pass the clutch cable and hot
starter cable through the cable
guide on the number plate.

3-1
MAINTENANCE INTERVALS
REGULAR INSPECTION AND ADJUSTMENTS
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
●●
VALVES
Check the valve clearances
●●The engine must be cold.
Inspect
●Check the valve seats and valve
stems for wear.
Replace
●
VALVE SPRINGS
Inspect
●Check the free length and the tilt.
Replace
●
VALVE LIFTERS
Inspect
●Check for scratches and wear.
Replace
●
CAMSHAFTS Inspect the camshaft surface.
Inspect
●Inspect the decompression system.
Replace
●
CAMSHAFT SPROCKETS
Inspect
●Check for wear on the teeth and for
damage.
Replace
●
PISTON
Inspect
●●Inspect crack.
Clean
●Inspect carbon deposits and eliminate
them.
Replace
●
PISTON RING
Inspect
●Check ring end gap.
Replace
●●
PISTON PIN
Inspect
●
Replace●
CYLINDER HEAD Inspect carbon deposits and eliminate
them.
Inspect and clean
●Change gasket.
CYLINDER
Inspect and clean
●Inspect score marks.
Replace
●Inspect wear.
CLUTCH
Inspect and adjust
●●Inspect housing, friction plate, clutch
plate and spring.
3

3-4
PRE-OPERATION INSPECTION AND MAINTENANCE
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.
GENERAL INSPECTION AND MAINTENANCETHROTTLE, CONTROL CABLE
Check routing and connection
●●Yamaha cable lube or SAE 10W-30
motor oil
Lubricate
●●
HOT STARTER, CLUTCH LEVER
Inspect free play
●
ItemAfter
break-
inEvery
race
Every
third
(or 500
km)Every
fifth (or
1,000
km)
As re-
quiredRemarks
Item Routine Page
CoolantCheck that coolant is filled up to the radiator cap. Check the cool-
ing system for leakage.P.3-5 – 6
FuelCheck that a fresh gasoline is filled in the fuel tank. Check the fuel
line for leakage.P.1-8
Engine oilCheck that the oil level is correct. Check the crankcase and oil line
for leakage.P.3-8 – 9
Gear shifter and clutchCheck that gears can be shifted correctly in order and that the
clutch operates smoothly.P.3-6
Throttle grip/HousingCheck that the throttle grip operation and free play are correctly
adjusted. Lubricate the throttle grip and housing, if necessary.P.3-6 – 7
Brakes Check the play of front brake and effect of front and rear brake. P.3-13 – 15
Drive chainCheck drive chain slack and alignment. Check that the drive chain
is lubricated properly.P.3-16
WheelsCheck for excessive wear and tire pressure. Check for loose
spokes and have no excessive play.P.3-19
SteeringCheck that the handlebar can be turned smoothly and have no ex-
cessive play.P.3-19 – 20
Front forks and rear shock
absorberCheck that they operate smoothly and there is no oil leakage.
P.3-17 – 19
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.—
Exhaust pipe Check that the exhaust pipe is tightly mounted and has no cracks. P.4-3 – 4
Rear wheel sprocket Check that the rear wheel sprocket tightening bolt is not loose. P.3-15 – 16
Lubrication Check for smooth operation. Lubricate if necessary. P.3-21
Bolts and nuts Check the chassis and engine for loose bolts and nuts. P.1-11
Lead connectorsCheck that the CDI magneto, CDI unit, and ignition coil are con-
nected tightly.P.1-3
SettingsIs the machine set suitably for the condition of the racing course
and weather or by taking into account the results of test runs be-
fore racing? Are inspection and maintenance completely done?P.7-1 – 10

3-6
ENGINE
Apply water on the radiator cap seal.
3. Radiator cap
2. Apply the specified pressure.
3. Inspect:
• Pressure
Impossible to maintain the speci-
fied pressure for 10 seconds
→
Replace.
CHECKING THE COOLING
SYSTEM
1. Inspect:
• Coolant level
2. Attach:
• Radiator cap tester "1" and adapt-
er "2"
3. Apply the specified pressure.
• Do not apply pressure more than
specified pressure.
• Radiator should be filled fully.
4. Inspect:
• Pressure
Impossible to maintain the speci-
fied pressure for 10 seconds
→
Repair.
•Radiator
• Radiator hose joint
Coolant leakage
→Repair or re-place.
• Radiator hose
Swelling
→Replace.
ADJUSTING THE CLUTCH CABLE
FREE PLAY
1. Check:
• Clutch lever free play "a"
Out of specification
→Adjust.
2. Adjust:
• Clutch lever free play
Clutch lever free play adjustment
steps:
a. Loosen the locknuts "1".
b. Turn the adjuster "2" until free
play "a" is within the specified lim-
its.
c. Tighten the locknuts.
• Before adjustment, expose the ad-
juster by moving the boot "3" and
cap "4" away.
• Make minute adjustment on the le-
ver side using the adjuster "5".
• After adjustment, check proper op-
eration of clutch lever.
3. Install:
• Cap "1"
•Boot "2"
Place the tip "a" of the cap in the boot.
ADJUSTING THE THROTTLE
CABLE FREE PLAY
1. Check:
• Throttle grip free play "a"
Out of specification
→Adjust.
2. Adjust:
• Throttle grip free play
Throttle grip free play adjustment
steps:
a. Slide the adjuster cover.
b. Loosen the locknut "1".
c. Turn the adjuster "2" until the
specified free play is obtained.
d. Tighten the locknut.
Before adjusting the throttle cable
free play, the engine idle speed
should be adjusted.
After adjusting the throttle cable
free play, start the engine and turn
the handlebar to right and left and
make sure that the engine idling
does not run faster.
Radiator cap opening
pressure:
110 kPa (1.1 kg/cm
2,
15.6 psi)
Radiator cap tester:
YU-24460-01/90890-
01325
Radiator cap tester
adapter:
YU-33984/90890-01352
Standard pressure:
180 kPa (1.8 kg/cm
2,
25.6 psi)
Clutch lever free play "a"
:
8–13 mm (0.31–0.51 in)
Locknut:
4 Nm (0.4 m•kg, 2.9
ft•lb)
Throttle grip free play
"a":
3–5 mm (0.12–0.20 in)
Locknut:
4 Nm (0.4 m•kg, 2.9
ft•lb)

3-8
ENGINE
CHECKING THE ENGINE OIL
LEVEL
1. Stand the machine on a level sur-
face.
• When checking the oil level make
sure that the machine is upright.
• Place the machine on a suitable
stand.
Never remove the oil tank cap just
after high speed operation. The
heated oil could spurt out. causing
danger. Wait until the oil cools
down to approximately 70°C
(158°F).
2. Idle the engine more than 3 min-
utes while keeping the machine
upright. Then stop the engine and
inspect the oil level.
3. Remove:
• Oil tank cap 1
4. Inspect:
• Oil level
Check that the engine oil is above
the level mark "a" and that the oil
does not come out when the
check bolt "1" is removed.
Below the level mark "a"
→Add oil
through the filler cap hole until it is
above the level mark "a".
Oil comes out at the check bolt
→
Drain the oil until it stops coming
out.
When inspecting the oil level, do not
screw the oil level gauge into the oil
tank. Insert the gauge lightly.
(For USA and CDN)
• Do not add any chemical addi-
tives. Engine oil also lubricates
the clutch and additives could
cause clutch slippage.
• Do not allow foreign material to
enter the crankcase.
(Except for USA and CDN)
• Do not add any chemical addi-
tives or use oils with a grade of
CD "a" or higher.
• Do not use oils labeled "ENERGY
CONSERVING II" "b" or higher.
Engine oil also lubricates the
clutch and additives could cause
clutch slippage.• Do not allow foreign material to
enter the crankcase.
5. Start the engine and let it warm up
for several minutes.
When the oil tank is empty, never
start the engine.
6. Idle the engine more than 10 sec-
onds while keeping the machine
upright. Then stop the engine and
add the oil to the maximum level.
7. Install:
• Oil tank cap
CHANGING THE ENGINE OIL
1. Start the engine and let it warm up
for several minutes.
2. Stop the engine and place an oil
pan under the drain bolt.
3. Remove:
• Oil tank plug "1"
• Oil filler cap "2"
• Drain bolt (with gasket) "3"
• Oil filter drain bolt (O-ring) "4"
• Drain bolt (with gasket) "5"
Drain the crankcase and oil tank
of its oil.
4. If the oil filter is to be replaced dur-
ing this oil change, remove the fol-
lowing parts and reinstall them.
Recommended oil:
Yamalube 4,
SAE10W30 or
SAE20W40
Yamalube 4-R,
SAE10W50
API service SG type or
higher, JASO standard
MA
Recommended oil:
SAE10W30,
SAE10W40,
SAE15W40, SAE20W40
or SAE20W50
API service SG type or
higher, JASO standard
MA

3-21
CHASSIS
LUBRICATION
To ensure smooth operation of all
components, lubricate your machine
during setup, after break-in, and after
every race.
1. All control cable
2. Clutch lever pivot
3. Shift pedal pivot
4. Footrest pivot
5. Throttle-to-handlebar contact
6. Drive chain
7. Tube guide cable winding por-
tion
8. Throttle cable end
9. Clutch cable end
10. Hot starter cable end
A. Use Yamaha cable lube or
equivalent on these areas.B. Use SAE 10W-30 motor oil or
suitable chain lubricants.
C. Lubricate the following areas
with high quality, lightweight lith-
ium-soap base grease.
Wipe off any excess grease, and
avoid getting grease on the brake
discs.

4-2
SEAT, FUEL TANK AND SIDE COVERS
REMOVING THE SIDE COVER
1. Remove:
• Bolt (side cover)
• Left side cover "1"
• Right side cover "2"
Draw the side cover downward to re-
move it because its claws "a" are in-
serted in the air filter case.
REMOVING THE NUMBER PLATE
1. Remove:
• Bolt (number plate)
• Number plate "1"
• The projection "a" is inserted into
the band of the number plate. Pull
the band off the projection before
removal.
• Remove the hot starter cable "2"
and clutch cable "3" from the cable
guide "b" on the number plate.
• The projection "c" on the lower
bracket is inserted into the number
plate. Remove the number plate by
pulling it off the projection.
INSTALLING THE AIR SCOOP
1. Install
• Air scoop "1"
• Bolt (air scoop)
Put the portion "a" of the flap of the air
filter case on the inside of the air
scoop.
Bolt (air scoop):
7 Nm (0.7 m•kg, 5.1
ft•lb)