2008 YAMAHA YFZ450 ECU

1-3
1
2
3
4
5
6
7
8
9
10
11

ing, use the proper gear and maintain a steady
speed when climbing a hill. If you stall or roll
backwards, follow the special procedure for
braking described in this manual. Dismount on
the uphill side or to a side if pointed straight up-
hill. Turn the ATV around and remount, following
the procedure described in this manual.

Always check for obstacles before operating in a
new area.

Never attempt to operate over large obstacles,
such as large rocks or fallen trees. Always follow
proper procedures when operating over obsta-
cles as described in this manual.

Always be careful when skidding or sliding.
Learn to safely control skidding or sliding by
practicing at low speeds and on level, smooth
terrain. On extremely slippery surfaces, such as
ice, go slowly and be very cautious in order to re-
duce the chance of skidding or sliding out of con-
trol.

Never operate an ATV in fast flowing water or in
water deeper than that recommended in this
manual. Remember that wet brakes may have
reduced stopping ability. Test your brakes after
leaving water. If necessary, apply them several
times to let friction dry out the linings.

Always use the size and type of tires specified in
this manual.

Always maintain proper tire pressure as de-
scribed in this manual.

Never modify an ATV through improper installa-
tion or use of accessories.

Never exceed the stated load capacity for an
ATV. Cargo should be properly distributed and
securely attached. Reduce speed and follow in-
structions in this manual for carrying cargo or
pulling a trailer. Allow greater distance for brak-
ing.
WARNING

EWB00061

Always turn off the engine when refueling.

Do not refuel right after the engine has been
running and is still very hot.

Do not spill gasoline on the engine or ex-
haust pipe/muffler when refueling. Never re-
fuel while smoking, or in the vicinity of
sparks, open flames, or other sources of ig-
nition such as the pilot lights of water heat-
ers and clothes dryers. Gasoline can catch
fire and you could be burned.

When transporting the ATV in another vehi-
cle, be sure it is kept upright and that the fuel

4-9
1
2
34
5
6
7
8
9
10
11

of gasoline or higher octane grade.
CAUTION:

ECB00070
Use only unleaded gasoline. The use of leaded
gasoline will cause severe damage to internal
engine parts, such as the valves and piston
rings, as well as to the exhaust system.
WARNING

EWB00310

Do not overfill the fuel tank. Fuel expands
when it heats up. If the fuel tank is overfilled,
fuel could spill out due to heat from the en-
gine or the sun.

Be careful not to spill fuel, especially on the
engine or exhaust pipe which can cause a
fire and severe injury. Wipe up any spilled
fuel immediately.

Do not refuel right after the engine has been
running and is still very hot.

Be sure the fuel tank cap is closed securely.
EBU18820
Fuel cock
The fuel cock supplies fuel from the tank to the car-
buretor while also filtering it.The fuel cock lever positions are explained as fol-
lows and shown in the illustrations.
OFF
With the fuel cock lever in this position, fuel will not
flow. Always turn the fuel cock lever to this position
when the engine is not running.
1. Arrow mark positioned over “OFF”

4-11
1
2
34
5
6
7
8
9
10
11

the starter (choke).
Move the starter (choke) in direction (b) to turn off
the starter (choke).
See the “Starting a cold engine” section on page
6-1 for proper operation.
EBU18890
Seat
To remove the seat
Insert your hand between the rear of the seat and
the rear fender, pull the seat lock lever upward and
pull up the seat at the rear.
To install the seat
Insert the projections on the front of the seat into
the seat holders and push down on the seat at the
rear.NOTE:

Make sure that the seat is securely fitted.
1. Starter (choke) “ ”
1
(a)(b)

1. Seat lock lever1

5-4
1
2
3
45
6
7
8
9
10
11

EBU19540
Fuel
Make sure that there is sufficient fuel in the tank.
(See page 4-8.)
WARNING

EWB00520

Do not overfill the fuel tank. Fuel expands
when it heats up. If the fuel tank is overfilled,
fuel could spill out due to heat from the en-
gine or the sun.

Be careful not to spill fuel, especially on the
engine or exhaust pipe which can cause a
fire and severe injury. Wipe up any spilled
fuel immediately.

Do not refuel right after the engine has been
running and is still very hot.

Be sure the fuel tank cap is closed securely.
EBU19560
Engine oil
Make sure that the engine oil is at the specified lev-
el. Add oil as necessary.
EBU19630
Coolant
Make sure that the coolant is at the specified level.
Add coolant as necessary. (See page 8-20.)
NOTE:

The coolant level must be checked on a cold en-
gine since the level varies with engine tempera-
ture.
WARNING

EWB00510
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.
EBU19710
Front and rear brakes
Brake lever and brake pedal

Check that there is no free play in the brake le-
ver. If there is free play, have a Yamaha dealer
check the brake system.

Check for correct brake pedal height. (See
page 8-36.) If the pedal height is incorrect, have
a Yamaha dealer adjust it.

Check the operation of the lever and pedal. They
should move smoothly and there should be a
firm feeling when the brakes are applied. If not,

6-7
1
2
3
4
56
7
8
9
10
11


Choose only accessories designed for your
ATV. Your Yamaha dealer has a variety of gen-
uine Yamaha accessories. Other accessories
may also be available on the market. However,
it is not possible for Yamaha to test all non-
Yamaha accessories, nor control over their qual-
ity or suitability. Choose a genuine Yamaha ac-
cessory, or one that is equivalent in design and
quality.

Accessories should be rigidly and securely
mounted. An accessory which can shift position
or come off while you are riding could affect your
ability to control the ATV.

Do not mount an accessory where it could inter-
fere with your ability to control the ATV. Exam-
ples include (but are not limited to) a heavy or
bulky object attached to the handlebars which
could make steering difficult, an accessory that
limits your ability to move around on the seat, or
one that limits your view.

Use extra caution when riding an ATV with ac-
cessories. The ATV may handle differently than
it does without accessories.
EBU20940
Loading
As originally equipped, this ATV is not designed to
carry cargo or tow a trailer. If you choose to add ac-
cessories so that you can carry cargo or tow a trail-
er, you must use common sense and good
judgment as the stability and handling of an ATV
can be changed. When adding accessories, keep
the following points in mind:

Never exceed the weight limits shown. An over-
loaded ATV can be unstable.

If you are carrying cargo and towing a trailer, in-
clude the tongue weight in the maximum ATV
load limit.

Load cargo on the carriers as close to the center
of the ATV as possible. Put cargo at the rear of
the front carrier, at the front of the rear carrier,
and center it.

Tie down cargo securely to the carriers. Make
sure cargo in the trailer cannot move around. A
shifting load can cause an accident. MAXIMUM LOADING LIMIT
ATV loading limit (total weight of rider, cargo,
accessories, and tongue):
100.0 kg (220 lb)

8-16
1
2
3
4
5
6
78
9
10
11
NOTE:

When adding oil, be careful not to overfill the en-
gine oil tank; the oil level rises faster starting from
the half-level-portion on the dipstick.
6. Insert the dipstick into the engine oil tank filler
hole, and then tighten the engine oil tank filler
cap.
CAUTION:

ECB00360
Make sure that the engine oil tank filler cap is
securely tightened, otherwise oil may seep out
when the engine is running.
To change the engine oil (with or without oil
filter element replacement)
1. Place the ATV on a level surface.
2. Remove the engine guard by removing the
bolts.3. Start the engine, warm it up for several min-
utes, and then turn it off.
4. Place an oil pan under the engine to collect
the used oil.
5. Remove the crankcase engine oil filler cap
and the crankcase engine oil drain bolt.
1. Engine guard
2. Bolt
1
2

8-27
1
2
3
4
5
6
78
9
10
11

12. Install the washer onto the air filter element
frame, and then insert the wing bolt into the
hole in the air filter element frame.
CAUTION:

ECB00451
Be sure to install the washer with the bent edge
facing outward as shown.
13. Insert the air filter element into the air filter
case, and then tighten the wing bolt.
14. Install the air filter case cover by hooking the
holders onto the air filter case.
15. Install the seat.
NOTE:

The air filter element should be cleaned every 20–
40 hours. It should be cleaned and lubricated more
often if the ATV is operated in extremely dusty ar-
eas. Each time the air filter element maintenance
is performed, check the air inlet of the air filter case
for obstructions. Check the air filter case rubber
joint to the carburetor fittings and the rubber joint
manifold fittings for an air-tight seal. Tighten all fit-
tings securely to avoid the possibility of unfiltered
air entering the engine.
CAUTION:

ECB00460

Make sure that the air filter element is prop-
erly seated in the air filter case.

Never operate the engine with the air filter el-
ement removed. This will allow unfiltered air
to enter the engine, causing rapid engine
wear and possible engine damage. Addition-
ally, operation without the air filter element
will affect carburetor jetting with subsequent
poor performance and possible engine over-
heating.
1. Washer
1