2012 YAMAHA YFZ450 engine

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
U1PD60E0.book Page 10 Monday, June 13, 2011 2:57 PM

8-11
8
To remove the spark plug
1. Remove the seat. (See page 4-12.)
2. Remove the bolts and the quick fastener screws shown.
3. Remove the fuel tank cap by turning it coun- terclockwise. WARNING! Never remove the
fuel tank cap while smoking, or in the vi-
cinity of sparks, open flames, or other
sources of ignition such as pilot lights of
water heaters and clothes dryers. Always
turn off the engine before removing the
fuel tank cap. Do not remove the fuel tank
cap immediately after the engine has been
running, as it is still very hot. Do not spill
gasoline on the engine, exhaust pipe or
muffler.
[EWB01871]
4. Pull the panel backward, and then remove the panel.
5. Install the fuel tank cap by turning it clockwise.
6. Remove the bolt, and then lift the rear of the fuel tank while sliding the tank slightly rear-
ward.1. Panel
2. Bolt
3. Quick fastener screw
4. Fuel tank cap
2
4 3 1
U1PD60E0.book Page 11 Monday, June 13, 2011 2:57 PM

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)
U1PD60E0.book Page 13 Monday, June 13, 2011 2:57 PM

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
U1PD60E0.book Page 14 Monday, June 13, 2011 2:57 PM

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
U1PD60E0.book Page 15 Monday, June 13, 2011 2:57 PM

8-16
85. 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. NOTICE:
Be sure the engine oil is at the correct lev-
el, otherwise engine damage may result.
[ECB00851]
TIPWhen 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. NOTICE: Make sure that the engine oil
tank filler cap is securely tightened; other-
wise, oil may seep out when the engine is
running.
[ECB00362]
To change the engine oil (with or without oil fil-
ter 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 and its
gasket.
1. Engine guard
2. Bolt
1
2
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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
U1PD60E0.book Page 17 Monday, June 13, 2011 2:57 PM