check engine YAMAHA YFZ450 2012 User Guide

8-3
8
EBU21743Periodic maintenance chart for the emission control system TIP
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. ITEM CHECK OR MAINTENANCE
JOB INITIAL
EVERY
Whichev- er comes first month136612
km
(mi) 320
(200) 1300
(800) 2500
(1600) 2500
(1600) 5000
(3200)
hours 20 80 160 160 320
1 *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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8-7
8
14*Chassis fasteners 
Make sure that all nuts, bolts, and screws are
properly tightened. √√√√√
15 *Shock absorber as-
semblies 
Check operation and correct if necessary.
 Check for oil leakage and replace if necessary. √√√
16 *Rear suspension re-
lay arm and con-
necting arm
pivoting points 
Check operation and correct if necessary. √√√√
17 *Steering shaft Lubricate with lithium-soap-based grease. √√√
18 *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. √√√
20 Engine oil 
Change.
 Check ATV for oil leakage, and correct if neces-
sary. √ √√√
21 Engine oil filter ele-
ment

Replace. √√√
22 Cooling system 
Check coolant level and ATV for coolant leakage,
and correct if necessary. √√√√√
 Replace coolant. Every 2 years
NO. ITEM
CHECK OR MAINTENANCE
JOB INITIAL EVERY
Whichev- er comes first month136612
km
(mi) 320
(200) 1300
(800) 2500
(1600) 2500
(1600) 5000
(3200)
hours 20 80 160 160 320U1PD60E0.book Page 7 Monday, June 13, 2011 2:57 PM

8-10
8To install the panel
1. Place the panel in the original position, and
then install the quick fastener screw and the
bolts. 2. Install the seat.
EBU23245Checking 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-
dance with the periodic maintenance and lubrica-
tion chart. In addition, the condition of the spark
plug can reveal the condition of the engine.1. Projection
2. Slot
1
1
2
2
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8-13
8
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).
TIPIf 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.
3. 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/CR8E1. Spark plug gapSpark plug gap:0.7 –0.8 mm (0.028– 0.031 in)
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8-14
8To install the spark plug
1. Clean the surface of the spark plug gasket and its mating surface, and then wipe off any
grime from the spark plug threads.
2. Install the spark plug with the spark plug wrench, and then tighten it to the specified
torque.
TIPIf a torque wrench is not available when installing
the 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.3. Install the spark plug cap.
4. Place the fuel tank in the original position, and then install the bolt.
5. Remove the fuel tank cap by turning it coun- terclockwise.
6. Place the panel in the original position. 7. Install the fuel tank cap by turning it clockwise.
8. Install the bolts and the quick fastener screws.
9. Install the seat.
EBU23307Engine 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:13 Nm (1.3 m ·kgf, 9.4 ft ·lbf)1. Projection
2. Slot
2 1
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8-15
8
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.
TIPTo 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, and then wipe the engine oil 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.
TIPThe engine oil should be between the minimum
and maximum level marks.1. Engine oil tank filler cap
2. Engine oil dipstick
3. Engine oil tank
4. Crankcase engine oil filler cap
5. Maximum level mark
6. Minimum level mark
4
3
1
1
2
5
6
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8-17
8
6. Remove the engine oil tank filler cap, and the
engine oil tank drain bolt and its gasket. 7. Check the gaskets for damage, and replace if
necessary.
TIPSkip steps 8 –11 if the oil filter element is not being
replaced.8. Remove the oil filter element cover by remov- ing the bolts, and then remove the oil filter el-
ement.
1. Crankcase engine oil drain bolt
2. Gasket
12
1. Engine oil tank drain bolt
2. Gasket
12
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8-20
8a higher quality than specified. In addition,
do not use oils labeled
“ENERGY CONSERV-
ING II” or higher.

Make sure that no foreign material enters the
crankcase.15. Start the engine, and then let it idle for several
minutes while checking it for oil leakage. If oil
is leaking, immediately turn the engine off and
check for the cause.
16. Turn the engine off, and then check the oil lev- el and correct it if necessary.
17. Install the engine guard by installing the bolts, and then tighten them to the specified torque.
NOTICE: Be sure to apply LOCTITE
® to the
engine guard bolts before installing them.
[ECB00371] EBU23470
Coolant The coolant level should be checked before each
ride. In addition, the coolant must be changed at
the intervals specified in the periodic maintenance
and lubrication chart.EBU27942To check the coolant level
1. Place the ATV on a level surface.TIPThe coolant level must be checked on a cold en-
gine since the level varies with engine tempera-
ture.2. Check the coolant level in the coolant reser- voir.TIPThe coolant should be between the minimum and
maximum level marks.
Tightening torque:Engine guard bolt:7 Nm (0.7 m ·kgf, 5.1 ft ·lbf)
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8-21
8
3. If the coolant is at or below the minimum level
mark, remove the coolant reservoir cap, add
coolant or distilled water to the maximum level
mark, and then install the reservoir cap.
NOTICE: If coolant is not available, use
distilled water or soft tap water instead. Do
not use hard water or salt water since they
are harmful to the engine. If water has
been used instead of coolant, replace it
with coolant as soon as possible, other-
wise the cooling system will not be pro- tected against frost and corrosion. If water
has been added to the coolant, have a
Yamaha dealer check the antifreeze con- tent of the coolant as soon as possible,
otherwise the effectiveness of the coolant
will be reduced.
[ECB01011]
TIP
The radiator fan is automatically switched on or
off according to the coolant temperature in the
radiator.
If the engine overheats, see page 8-58 for fur-
ther instructions.EBU23564To change the coolant
WARNING
EWB01890Wait for the engine and radiator to cool before
removing the radiator cap. You could be
burned by hot fluid and steam blown out under
1. Maximum level mark
2. Minimum level mark
3. Coolant reservoir
4. Coolant reservoir cap
1
2 4
3
Coolant reservoir capacity (up to the maxi-
mum level mark):
0.29 L (0.31 US qt, 0.26 Imp.qt)
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8-24
813. Remove the radiator cap to check the coolant
level in the radiator. If it is low, add sufficient
coolant until it reaches the top of the radiator,
and then install the radiator cap.
14. Start the engine, and then check for coolant leakage.
TIPIf any leakage is found, have a Yamaha dealer
check the cooling system.15. Install the panel.EBU23707Cleaning the air filter element The air filter element should be cleaned at the in-
tervals specified in the periodic maintenance and
lubrication chart. Clean or, if necessary, replace
the air filter element more frequently if you are
riding in unusually wet or dusty areas.TIPThere is a check hose at the bottom of the air filter
case. If dust or water collects in this hose, empty
the hose and clean the air filter element and air fil-
ter case.
1. Place the ATV on a level surface.
2. Remove the seat. (See page 4-12.)
3. Remove the air filter case cover by unhookingthe holders.1. Air filter case check hose
1
U1PD60E0.book Page 24 Monday, June 13, 2011 2:57 PM