2008 YAMAHA YFZ450 check engine

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the transmission.

Always use the clutch when changing gears.
The engine, transmission and drive train are
not designed to withstand the shock of
forced shifting and can be damaged by shift-
ing without using the clutch.
EBU20670
Engine break-in
There is never a more important period in the life of
your engine than the first 20 hours of riding. For
this reason, you should read the following material
carefully.
Since the engine is brand new, do not put an ex-
cessive load on it for the first 20 hours. The various
parts in the engine wear and polish themselves to
the correct operating clearances. During this peri-
od, prolonged full-throttle operation or any condi-
tion that might result in engine overheating must
be avoided.
0–10 hours
Avoid prolonged operation above 1/2 throttle. Vary
the speed of the ATV regularly. Do not operate it at
one set throttle position.
10–20 hours
Avoid prolonged operation above 3/4 throttle. Rev
the engine through the gears freely, but do not use
full throttle at any time.
20 hours and beyond
The ATV can now be operated normally.CAUTION:

ECB00220
If any engine trouble should occur during the
engine break-in period, immediately have a
Yamaha dealer check the ATV.
EBU20721
Parking
When parking the ATV, stop the engine, shift into
first gear, apply the parking brake, and then turn
the fuel cock to “OFF”.

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EBU21742
Periodic maintenance chart for the emission control system
NOTE:


For ATVs not equipped with an odometer or an hour meter, follow the month maintenance intervals.

For ATVs equipped with an odometer or an hour meter, follow the km (mi) or hours maintenance inter-
vals. However, keep in mind that if the ATV isn’t used for a long period of time, the month maintenance
intervals should be followed.

Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools,
data and technical skills.
NO. ITEMCHECK OR MAINTENANCE
JOBINITIAL EVERY
Whichev-
er comes
firstmonth 1 3 6 6 12
km
(mi)320
(200)1300
(800)2500
(1600)2500
(1600)5000
(3200)
hours 20 80 160 160 3201
*
Fuel line


Check fuel hoses for cracks or other damage, and
replace if necessary.
√√√
2 Spark plug

Check condition and clean, regap, or replace if
necessary.
√√√√√
3
*
Valves


Check valve clearance and adjust if necessary.
√ √√√
4
*
Carburetor


Check starter (choke) operation and correct if nec-
essary.

Check engine idling speed and adjust if neces-
sary.
√√√√
5
*
Crankcase breather
system


Check breather hose for cracks or other damage,
and replace if necessary.
√√√

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*
Swingarm pivots

Check operation and for excessive play, and
replace bearings if necessary.

Lubricate with molybdenum disulfide grease.
√√√
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*
Upper and lower
arm pivots


Lubricate with lithium-soap-based grease.
√√√
12 Drive chain

Check chain slack and adjust if necessary.

Check rear wheel alignment and correct if necess-
sary.

Clean and lubricate.
√√√√√
13
*
Drive chain rollers


Check for wear and replace if necessary.
√√√
14
*
Chassis fasteners


Make sure that all nuts, bolts, and screws are
properly tightened.
√√√√√
15
*
Shock absorber
assemblies


Check operation and correct if necessary.

Check for oil leakage and replace if necessary.
√√√
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*
Rear suspension
relay arm and con-
necting arm pivot-
ing points


Check operation and correct if necessary.

Lubricate with lithium-soap-based grease.
√√√√
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*
Steering shaft


Lubricate with lithium-soap-based grease.
√√√
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*
Steering system


Check operation and repair or replace if damaged.

Check toe-in and adjust if necessary.
√√√√√
19
*
Engine mount


Check for cracks or other damage, and replace if
necessary.
√√√
NO. ITEMCHECK OR MAINTENANCE
JOBINITIAL EVERY
Whichev-
er comes
firstmonth136612
km
(mi)320
(200)1300
(800)2500
(1600)2500
(1600)5000
(3200)
hours 20 80 160 160 320

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20 Engine oil

Change.

Check ATV for oil leakage, and correct if neces-
sary.
√ √√√
21Engine oil filter ele-
ment

Clean or replace if necessary.
√√√
22 Cooling system

Check coolant level and ATV for coolant leakage,
and correct if necessary.
√√√√√

Replace coolant. Every 2 years
23
*
Moving parts and
cables

Lubricate.
√√√√
24
*
Throttle lever hous-
ing and cable


Check operation and correct if necessary.

Check throttle cable free play and adjust if neces-
sary.

Lubricate throttle lever housing and cable.
√√√√√
25
*
Front and rear brake
switches

Check operation and correct if necessary.
√√√√√
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*
Lights and switches

Check operation and correct if necessary.

Adjust headlight beams.
√√√√√
NO. ITEMCHECK OR MAINTENANCE
JOBINITIAL EVERY
Whichev-
er comes
firstmonth 1 3 6 6 12
km
(mi)320
(200)1300
(800)2500
(1600)2500
(1600)5000
(3200)
hours 20 80 160 160 320

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To install the panel1. Place the panel in the original position, and
then install the quick fastener screw and the
bolts.
2. Install the seat.
EBU23241
Checking the spark plug
The spark plug is an important engine component,
which is easy to check. Since heat and deposits
will cause any spark plug to slowly erode, the spark
plug should be removed and checked in accor-
1. Bolt
1

1. Projection
2. Slot
1
1 22

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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

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2. Clean the surface of the spark plug gasket
and its mating surface, and then wipe off any
grime from the spark plug threads.
3. Install the spark plug with the spark plug
wrench, and then tighten it to the specified
torque.
NOTE:

If a torque wrench is not available when installing
a spark plug, a good estimate of the correct torque
is 1/4–1/2 turn past finger tight. However, the spark
plug should be tightened to the specified torque as
soon as possible.
4. Install the spark plug cap.
5. Place the fuel tank in the original position, and
then install the bolt.
6. Remove the fuel tank cap by turning it coun-
terclockwise.
7. Place the panel in the original position.8. Install the fuel tank cap by turning it clockwise.
9. Install the bolts and the quick fastener screws.
10. Install the seat.
EBU23304
Engine oil and oil filter element
The engine oil level should be checked before
each ride. In addition, the oil must be changed and
the oil filter element replaced at the intervals spec-
ified in the periodic maintenance and lubrication
chart. Tightening torque:
Spark plug:
12.5 Nm (1.25 m·kgf, 9.0 ft·lbf)
1. Projection
2. Slot
21

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To check the engine oil level
1. Place the ATV on a level surface.
2. Start the engine, warm it up until the engine oil
has reached a normal temperature of 40 °C
(104 °F), let it continue to idle for ten seconds
or more, and then turn the engine off.
NOTE:

To achieve the proper engine oil temperature for
an accurate oil level reading, the engine must have
first completely cooled down, and then warmed up
again for several minutes to normal operating tem-
perature.
3. Remove the engine oil tank filler cap, wipe the
dipstick off with a clean rag.
4. Insert the dipstick into the filler hole (without
screwing it in), and then remove it again to
check the oil level.
NOTE:

The engine oil should be between the minimum
and maximum level marks.
5. If the engine oil is at or below the minimum
level mark, add sufficient oil of the recom-
mended type through the engine oil tank filler
hole to raise it to the correct level.
1. Engine oil tank filler cap
2. Dipstick
3. Engine oil tank
4. Engine oil filler cap
5. Maximum level mark
6. Minimum level mark
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