2008 YAMAHA YFZ450 fuel

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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)

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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.

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increasing the chance of an accident. Test the
brakes after washing. Apply the brakes several
times at slow speeds to let friction dry out the
linings.
EBU25932
Storage
Short-term
Always store your ATV in a cool, dry place and, if
necessary, protect it against dust with a porous
cover.
CAUTION:

ECB00720

Storing the ATV in a poorly ventilated room
or covering it with a tarp while it is still wet,
will allow water and humidity to seep in and
cause rust.

To prevent corrosion, avoid damp cellars,
stables (because of the presence of ammo-
nia) and areas where strong chemicals are
stored.
Long-term
Before storing your ATV for several months:
1. Follow all the instructions in the “Cleaning”section of this chapter.
2. Turn the fuel cock lever to “OFF”.
3. Drain the carburetor float chamber by loosen-
ing the drain bolt; this will prevent fuel deposits
from building up. Pour the drained fuel into the
fuel tank.
4. Fill up the fuel tank and add fuel stabilizer (if
available) to prevent the fuel from deteriorat-
ing.
5. Perform the following steps to protect the cyl-
inder, piston rings, etc. from corrosion.
a. Remove the spark plug cap and spark
plug.
b. Pour a teaspoonful of engine oil into the
spark plug bore.
c. Install the spark plug cap onto the spark
plug, and then place the spark plug on the
cylinder head so that the electrodes are
grounded. (This will limit sparking during
the next step.)
d. Turn the engine over several times with
the starter. (This will coat the cylinder wall Specified amount:
7.5 ml of stabilizer to each liter of fuel (or 1 oz
of stabilizer to each gallon of fuel)

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EBU25960
SPECIFICATIONS
EBU25975
Dimensions:
Overall length:
1840 mm (72.4 in)
Overall width:
1170 mm (46.1 in)
Overall height:
1090 mm (42.9 in)
Seat height:
810 mm (31.9 in)
Wheelbase:
1280 mm (50.4 in)
Ground clearance:
255 mm (10.0 in)
Minimum turning radius:
3500 mm (138 in)
Weight:
With oil and fuel:
169.0 kg (373 lb)
Engine:
Engine type:
Liquid cooled 4-stroke, DOHC
Cylinder arrangement:
Forward-inclined single cylinder
Displacement:
449.0 cm
3

Bore
×
stroke:
95.0
×
63.4 mm (3.74
×
2.50 in)Compression ratio:
11.40 :1
Starting system:
Electric starter
Lubrication system:
Dry sump

Engine oil:
Type:
SAE5W30 or SAE10W30 or SAE10W40 or SAE15W40
or SAE20W40 or SAE20W50
Recommended engine oil grade:
API service SG type or higher, JASO standard MA
-20˚-10˚0˚
10˚20˚30˚40˚50˚C
10W/30
15W/4020W/4020W/50
10W/40
5W/30

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Engine oil quantity:
Without oil filter element replacement:
1.75 L (1.85 US qt) (1.54 Imp.qt)
Quantity in oil tank:
1.55 L (1.64 US qt) (1.36 Imp.qt)
Quantity in crankcase:
0.20 L (0.21 US qt) (0.18 Imp.qt)
With oil filter element replacement:
1.85 L (1.96 US qt) (1.63 Imp.qt)
Quantity in oil tank:
1.55 L (1.64 US qt) (1.36 Imp.qt)
Quantity in crankcase:
0.30 L (0.32 US qt) (0.26 Imp.qt)
Cooling system:
Coolant reservoir capacity (up to the maximum level mark):
0.29 L (0.31 US qt) (0.26 Imp.qt)
Radiator capacity (including all routes):
1.30 L (1.37 US qt) (1.14 Imp.qt)
Air filter:
Air filter element:
Wet element
Fuel:
Recommended fuel:
Premium unleaded gasoline only
Fuel tank capacity:
10.0 L (2.64 US gal) (2.20 Imp.gal)
Fuel reserve amount:
1.9 L (0.50 US gal) (0.42 Imp.gal)
Carburetor:
Manufacturer:
KEIHINType x quantity:
FCR39H x 1
Spark plug (s):
Manufacturer/model:
NGK/CR8E
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
Clutch:
Clutch type:
Wet, multiple-disc
Transmission:
Primary reduction system:
Spur gear
Primary reduction ratio:
62/22 (2.818)
Secondary reduction system:
Chain drive
Secondary reduction ratio:
38/14 (2.714)
Transmission type:
Constant mesh 5-speed
Operation:
Left foot operation
1st:
29/12 (2.416)
2nd:
27/14 (1.928)
3rd:
25/16 (1.562)
4th:
23/18 (1.277)

INDEX
A
Accessories and loading ................................................ 6-6
Air filter element, cleaning ............................................ 8-24
B
Battery .......................................................................... 8-45
Brake and clutch levers, checking and lubricating ....... 8-42
Brake and shift pedals, checking and lubricating ......... 8-43
Brake fluid, changing.................................................... 8-35
Brake fluid level, checking............................................ 8-32
Brake lever ..................................................................... 4-5
Brake lever free play, checking the front ...................... 8-36
Brake light switches ..................................................... 8-39
Brake pads, checking the front and rear ...................... 8-31
Brake pedal .................................................................... 4-5
Brake pedal position, checking .................................... 8-36
Brakes, front and rear .................................................... 5-4
C
Cables, checking and lubricating ................................. 8-41
Carburetor, adjusting.................................................... 8-29
Chassis fasteners........................................................... 5-8
Cleaning ......................................................................... 9-1
Clutch lever .................................................................... 4-5
Clutch lever free play, adjusting ................................... 8-39
Coolant ................................................................. 5-4
,
8-20
Coolant temperature warning light ................................. 4-1
D
Drive chain ..................................................................... 5-5
Drive chain, lubricating ................................................. 8-41
E
Engine break-in .............................................................. 6-5
Engine, cold start ........................................................... 6-1
Engine idling speed ...................................................... 8-30
Engine oil ....................................................................... 5-4
Engine oil and oil filter element .................................... 8-14
Engine, starting a warm ................................................. 6-3
Engine stop switch ......................................................... 4-2
F
Fuel ........................................................................ 4-8
,
5-4
Fuel cock ........................................................................ 4-9
Fuel tank cap.................................................................. 4-7
Fuse, replacing............................................................. 8-46
H
Handlebar switches ........................................................ 4-2
Headlight beam, adjusting............................................ 8-49
Headlight bulb, replacing.............................................. 8-47
I
Identification numbers .................................................. 11-1
Indicator light and warning light...................................... 4-1
Instruments, lights and switches .................................... 5-8
K
Key identification number ............................................. 11-1