2008 YAMAHA YFZ450 Owners Manual

8-46
1
2
3
4
5
6
78
9
10
11

To store the battery
1. If the ATV will not be used for more than one
month, remove the battery, fully charge it, and
then place it in a cool, dry place.
2. If the battery will be stored for more than two
months, check it at least once a month and ful-
ly charge it if necessary.
To install the battery
NOTE:

Be sure the battery is fully charged.
1. Place the battery in its compartment.
2. Make sure to properly connect the battery
leads to the battery terminals.
CAUTION:

ECB00630

Always keep the battery charged. Storing a
discharged battery can cause permanent
battery damage.

To charge a sealed-type (MF) battery, a spe-
cial constant-voltage battery charger is re-
quired. Using a conventional battery charger
will damage the battery. If you do not have
access to a constant-voltage battery charg-
er, have a Yamaha dealer charge your bat-
tery.
EBU25262
Replacing the fuse
The fuse holder is located on the right side of the
ATV.
If the fuse is blown, replace it as follows.
1. Turn the key to “OFF” and turn off all electrical
circuits.
CAUTION:

ECB00640
To prevent accidental short-circuiting, turn off
1. Fuse
2. Spare fuse
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

8-51
1
2
3
4
5
6
78
9
10
11
Front

2. Lower the ATV to the ground.
3. Tighten the wheel nuts to the specified
torques.
EBU25740
Troubleshooting
Although Yamaha ATVs receive a thorough in-spection before shipment from the factory, trouble
may occur during operation. Any problem in the fu-
el, compression, or ignition systems, for example,
can cause poor starting and loss of power.
The following troubleshooting charts represent
quick and easy procedures for checking these vital
systems yourself. However, should your ATV re-
quire any repair, take it to a Yamaha dealer, whose
skilled technicians have the necessary tools, expe-
rience, and know-how to service the ATV properly.
Use only genuine Yamaha replacement parts. Im-
itation parts may look like Yamaha parts, but they
are often inferior, have a shorter service life and
can lead to expensive repair bills.
WARNING
EWB02280
Do not smoke when checking the fuel system.
Fuel can ignite or explode, causing severe inju-
ry or property damage. Make sure there are no
open flames or sparks in the area, including pi-
lot lights from water heaters or furnaces.
1. Arrow mark
Tightening torques:
Front wheel nut:
45 Nm (4.5 m·kgf, 33 ft·lbf)
Rear wheel nut:
45 Nm (4.5 m·kgf, 33 ft·lbf)

8-52
1
2
3
4
5
6
78
9
10
11

EBU25781
Troubleshooting charts
Starting problems or poor engine performance
Check the fuel level in
the fuel tank.1. Fuel
There is enough fuel.
There is no fuel.
Check the compression.
Supply fuel.
The engine does not start.
Check the compression.
Operate the electric starter.2. Compression
There is compression.
There is no compression.
Check the ignition.
Have a Yamaha dealer
check the ATV.
Remove the spark plug
and check the electrodes.3. Ignition
Wipe off with a dry cloth and correct the
spark plug gap, or replace the spark plug.
Have a Yamaha dealer check the ATV.
The engine does not start.
Have a Yamaha dealer
check the ATV.
The engine does not start.
Check the battery.
Operate the electric starter.4. Battery
The engine turns over
quickly.
The engine turns over
slowly.
The battery is good.Check the battery lead connections,
and charge the battery if necessary.
DryWet
Open the throttle halfway and operate
the electric starter.

8-53
1
2
3
4
5
6
78
9
10
11

Engine overheating
WARNING

EWB02290
Wait for the engine and radiator to cool before removing the radiator cap. You could be burned by
hot fluid and steam blown out under pressure. Always put a thick rag over the cap when opening.
Allow any remaining pressure to escape before completely removing the cap.
NOTE:

If coolant is not available, tap water can be temporarily used instead, provided that it is changed to the rec-
ommended coolant as soon as possible.
Wait until the
engine has cooled.
Check the coolant level in the
reservoir and radiator.
The coolant level
is OK.The coolant level is low.
Check the cooling system
for leakage.
Have a Yamaha dealer check
and repair the cooling system.Add coolant. (See NOTE.)
Start the engine. If the engine overheats again, have a
Yamaha dealer check and repair the cooling system.
There is
leakage.
There is
no leakage.