2008 YAMAHA YFZ450 light

8-11
1
2
3
4
5
6
78
9
10
11

dance with the periodic maintenance and lubrica-
tion chart. In addition, the condition of the spark
plug can reveal the condition of the engine.
To remove the spark plug
1. Remove the seat. (See page 4-11.)
2. Remove the bolts and the quick fastener
screws shown.
3. Remove the fuel tank cap by turning it coun-
terclockwise.
WARNING
EWB01870

Always turn off the engine before removing
the fuel tank cap.

Do not remove the fuel tank cap immediately
after the engine has been running and is still
very hot.

Do not spill gasoline on the engine, exhaust
pipe or muffler.

Never remove the fuel tank cap while smok-
ing, or in the vicinity of sparks, open flames,
or other sources of ignition such as the pilot
lights of water heaters and clothes dryers.
4. Pull the panel backward, and then remove the
panel.
5. Install the fuel tank cap by turning it clockwise.
6. Remove the bolt, lift the rear of the fuel tank,
and then tilt it back.
1. Panel
2. Bolt
3. Quick fastener screw
4. Fuel tank cap
2
4
3
1

8-13
1
2
3
4
5
6
78
9
10
11

kit.
To check the spark plug
1. Check that the porcelain insulator around the
center electrode of the spark plug is a medi-
um-to-light tan (the ideal color when the ATV
is ridden normally).
NOTE:

If the spark plug shows a distinctly different color,
the engine could be operating improperly. Do not
attempt to diagnose such problems yourself. In-
stead, have a Yamaha dealer check the ATV.
2. Check the spark plug for electrode erosionand excessive carbon or other deposits, and
replace it if necessary.
To install the spark plug
1. Measure the spark plug gap with a wire thick-
ness gauge and, if necessary, adjust the gap
to specification.
1. Spark plug wrench
1

Specified spark plug:
NGK/CR8E
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
1. Spark plug gap

8-28
1
2
3
4
5
6
78
9
10
11

EBU27701
Cleaning the spark arrester
Select a well-ventilated area free of combustible
materials and make sure the exhaust and muffler
are cool.
1. Remove the bolt.
2. Remove the tailpipe by pulling it out of the
muffler.
3. Tap the tailpipe lightly, and then use a wire
brush to remove any carbon deposits from the
spark arrester portion of the tailpipe and inside
of the tailpipe housing.4. Insert the tailpipe into the muffler and align the
bolt holes.
5. Install the bolt and tighten it to the specified
torque.
6. Remove the purging bolt.
1. Bolt
1

1. Tailpipe
2. Spark arrester
Tightening torque:
Tailpipe bolt:
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
1
2

8-39
1
2
3
4
5
6
78
9
10
11

EBU24740
Brake light switches
The operation of the brake light switches must be
checked and, if necessary, adjusted at the inter-
vals specified in the periodic maintenance and lu-
brication chart.
The brake light switch for the brake pedal can be
adjusted as follows, but the other brake light
switches should be adjusted by a Yamaha dealer.
NOTE:

The brake light switch is properly adjusted when
the brake light comes on just before braking takes
effect.
Turn the adjusting nut while holding the brake light
switch in place. To make the brake light come on
earlier, turn the adjusting nut in direction (a). To
make the brake light come on later, turn the adjust-
ing nut in direction (b).
EBU24820
Adjusting the clutch lever free play
The clutch lever free play must be checked and, if
necessary, adjusted at the intervals specified in
the periodic maintenance and lubrication chart.
The clutch lever free play should measure 8.0–
13.0 mm (0.31–0.51 in) as shown. If the free play
is incorrect, adjust it as follows.
1. Brake light switch
2. Brake light switch adjusting nut
(a)
(b)1
2

8-47
1
2
3
4
5
6
78
9
10
11

the main switch when checking or replacing a
fuse.
2. Remove the blown fuse, and then install a
new fuse of the specified amperage.
WARNING

EWB02171
Always use a fuse of the specified rating, and
never use a substitute object in place of the
proper fuse. An improper fuse or a substitute
object can cause damage to the electrical sys-
tem, which could lead to a fire.
3. Turn the key to “ON” and turn on the electrical
circuits to check if the devices operate.
4. If the fuse immediately blows again, have a
Yamaha dealer check the electrical system.
EBU25440
Replacing a headlight bulb
If a headlight bulb burns out, replace it as follows.
1. Remove the headlight unit by removing the
bolts.2. Disconnect the headlight coupler.
3. Remove the headlight bulb holder cover. Specified fuse:
15.0 A
1. Headlight assembly
2. Bolt21

8-48
1
2
3
4
5
6
78
9
10
11

4. Remove the headlight bulb holder by pushing
it in and turning it counterclockwise, and then
remove the defective bulb.
WARNING

EWB02230
Do not touch a headlight bulb when it is on or
immediately after it is turned off. You can be
burned or a fire could start if the bulb touches
something flammable. Wait for the bulb to cool
before touching or removing it.
5. Place a new headlight bulb into position.
1. Headlight bulb holder cover
2. Headlight coupler
1
2

1. Headlight bulb holder
1

8-49
1
2
3
4
5
6
78
9
10
11
CAUTION:

ECB00650
Do not touch the glass part of the headlight
bulb to keep it free from oil, otherwise the
transparency of the glass, the luminosity of the
bulb, and the bulb life will be adversely affect-
ed. Thoroughly clean off any dirt and finger-
prints on the headlight bulb using a cloth
moistened with alcohol or thinner.
6. Install the headlight bulb holder by pushing it
in and turning it clockwise.
7. Install the headlight bulb holder cover.8. Connect the headlight coupler.
9. Install the headlight unit by installing the bolts.
10. Adjust the headlight beam if necessary.
EBU25550
Adjusting a headlight beam
CAUTION:

ECB00690
It is advisable to have a Yamaha dealer make
this adjustment.
To raise a headlight beam, turn the adjusting
screw in direction (a).
To lower a headlight beam, turn the adjusting
screw in direction (b).
1. Do not touch the glass part of the bulb.
1

1. Headlight beam adjusting screw
1(a)
(b)

8-50
1
2
3
4
5
6
78
9
10
11

EBU25580
Replacing the tail/brake light bulb
If the tail/brake light bulb burns out, have a
Yamaha dealer replace it.
EBU25650
Removing a wheel
1. Loosen the wheel nuts.
FrontRear
2. Elevate the ATV and place a suitable stand
under the frame.
3. Remove the nuts from the wheel.
4. Remove the wheel.
EBU25670
Installing a wheel
1. Install the wheel and the nuts.
NOTE:

When installing a front wheel, make sure its arrow
mark points toward the rotating direction of the
wheel.
1. Nut
1. Nut