bolt pattern YAMAHA YZ450F 2012 Owners Manual

4-10
CAMSHAFTS
REMOVING THE CAMSHAFT
1. Remove:
• Timing mark accessing screw "1"
• Crankshaft end accessing screw
"2"
2. Align:
• Alignment mark
Checking steps:
a. Turn the crankshaft counterclock-
wise with a wrench.
b. Align the alignment mark "a" on
the rotor with the alignment mark
"b" on the crankcase cover.
Make sure that the alignment mark
"c" on the exhaust camshaft sprocket
and the alignment mark "d" on the in-
take camshaft sprocket are aligned
with the edge of the cylinder head.
3. Remove:
• Timing chain tensioner cap bolt
"1"
• Timing chain tensioner "2"
• Gasket4. Remove:
• Bolt (camshaft cap) "1"
• Camshaft cap "2"
• Clip
Remove the bolts (camshaft cap) in a
crisscross pattern, working from the
outside in.
The bolts (camshaft cap) must be
removed evenly to prevent dam-
age to the cylinder head, cam-
shafts or camshaft caps.
5. Remove:
• Exhaust camshaft "1"
• Intake camshaft "2"
Attach a wire "3" to the timing chain to
prevent it from falling into the crank-
case.
CHECKING THE CAMSHAFT
1. Inspect:
• Cam lobe
Pitting/scratches/blue discolor-
ation → Replace.
2. Measure:
• Cam lobe length "a" and "b"
Out of specification → Replace.3. Measure:
• Runout (camshaft)
Out of specification → Replace.
Cam lobes length:
Intake "a":
37.750–37.850 mm
(1.4862–1.4902 in)
:
37.650 mm (1.4823 in)
Intake "b":
28.129–28.229 mm
(1.1072–1.1114 in)
:
28.029 mm (1.1035 in)
Exhaust "a":
33.540–33.640 mm
(1.3205–1.3244 in)
:
33.440 mm (1.3165 in)
Exhaust "b":
24.769–24.869 mm
(0.9752–0.9791 in)
:
24.669 mm (0.9712 in)
Runout (camshaft):
Less than 0.03 mm
(0.0012 in)

4-11
CAMSHAFTS
4. Measure:
• Camshaft-to-cap clearance
Out of specification → Measure
camshaft outside diameter.
Measurement steps:
a. Install the camshaft onto the cylin-
der head.
b. Position a strip of Plastigauge
®
"1" onto the camshaft.
c. Install the clip, dowel pins and
camshaft caps.
• Tighten the bolts (camshaft cap) in
a crisscross pattern from innermost
to outer caps.
• Do not turn the camshaft when
measuring clearance with the
Plastigauge
®.
d. Remove the camshaft caps and
measure the width of the Plasti-
gauge
® "1".
5. Measure:
• Camshaft outside diameter "a"
Out of specification → Replace
the camshaft.
Within specification → Replace
camshaft case and camshaft
caps as a set.CHECKING THE CAMSHAFT
SPROCKET
1. Inspect:
• Camshaft sprocket "1"
Wear/damage→Replace the
camshaft assembly and timing
chain as a set.
CHECKING THE
DECOMPRESSION SYSTEM
1. Check:
• Decompression system
Checking steps:
a. Check that the decompression
mechanism cam "1" moves
smoothly.
b. Check that the decompression
mechanism cam lever pin "2" proj-
ects from the camshaft.
CHECKING THE TIMING CHAIN
TENSIONER
1. Check:
• While pressing the tensioner rod
lightly with fingers, use a thin
screwdriver "1" and wind the ten-
sioner rod up fully clockwise.
• When releasing the screwdriver
by pressing lightly with fingers,
make sure that the tensioner rod
will come out smoothly.
• If not, replace the tensioner as-
sembly.INSTALLING THE CAMSHAFT
1. Install:
• Exhaust camshaft "1"
• Intake camshaft "2"
Installation steps:
a. Turn the crankshaft counterclock-
wise with a wrench.
• Apply the molybdenum disulfide oil
on the camshafts.
• Apply the engine oil on the decom-
pression system.
• Fill the cylinder head with engine oil
up to the tops "a" of the valve lifters.
b. Align the alignment mark "a" on
the rotor with the alignment mark
"b" on the crankcase cover.
The alignment mark "a" on the ro-
tor is there for camshaft installa-
tion. This alignment mark is
stamped 23° ATDC.
Camshaft-to-cap clear-
ance:
0.028–0.062 mm
(0.0011–0.0024 in)
:0.08 mm (0.003
in)
Bolt (camshaft cap):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Camshaft outside diame-
ter:
21.959–21.972 mm
(0.8645–0.8650 in)

4-15
CYLINDER HEAD
CHECKING THE CYLINDER HEAD
1. Eliminate:
• Carbon deposits (from the com-
bustion chambers)
Use a rounded scraper.
Do not use a sharp instrument to
avoid damaging or scratching:
• Spark plug threads
• Valve seats
2. Inspect:
• Cylinder head
Scratches/damage → Replace.
Replace the titanium valves with the
cylinder head.
Refer to"CHECKING THE VALVE".
3. Measure:
• Cylinder head warpage
Out of specification → Resur-
face.
Warpage measurement and resur-
facing steps:
a. Place a straightedge and a feeler
gauge across the cylinder head.
b. Use a feeler gauge to measure
the warpage.
c. If the warpage is out of specifica-
tion, resurface the cylinder head.
d. Place a 400–600 grit wet sandpa-
per on the surface plate, and re-
surface the head using a figure-
eight sanding pattern.
To ensure an even surface rotate the
cylinder head several times.
INSTALLING THE CYLINDER
HEAD
1. Install:
• Timing chain guide (intake side)
"1"
• Dowel pin "2"
• Cylinder head gasket "3"
• Cylinder head "4"
While pulling up the timing chain, in-
stall the timing chain guide (intake
side) and cylinder head.
2. Install:
• Washer "1"
• Bolts "2"
Installation steps:
Tighten the cylinder head using
the rotation angle procedure to ob-
tain uniform tightening torque.
a. Wash the threads and contact
surfaces of the bolts, the contact
surfaces of the plain washers, the
contact surface of the cylinder
head, and the threads of the
crankcase.
b. Apply the molybdenum disulfide
grease on the threads and con-
tact surfaces of the bolts and on
both contact surfaces of the plain
washers.
c. Install the plain washers and
bolts.d. Tighten the bolts to the specified
torque in two or three steps in the
proper tightening sequence as
shown.
e. Remove the bolts.
f. Again apply the molybdenum dis-
ulfide grease on the threads and
contact surfaces of the bolts and
on both contact surfaces of the
plain washers.
g. Retighten the bolts.
Tighten the bolts to the specified
torque in two or three steps in the
proper tightening sequence as
shown.
h. Put a mark on the corner "1" of the
bolt (cylinder head) and the cylin-
der head "2" as shown. Cylinder head warpage:
Less than 0.05 mm
(0.002 in)
Bolts (cylinder head):
1st:
30 Nm (3.0 m•kg, 22
ft•lb)
Bolts (cylinder head):
2nd:
20 Nm (2.0 m•kg, 14
ft•lb)

4-28
CLUTCH
INSTALLING THE CLUTCH
1. Install:
• Primary driven gear "1"
• Thrust washer "2"
• Clutch boss "3"
Apply the engine oil on the primary
driven gear inner circumference.
2. Install:
• Conical washer "1"
• Nut (clutch boss) "2"
Make sure to tighten to specifica-
tion; otherwise, it may damage the
other part that is fastened togeth-
er.
• Apply engine oil to the threads and
contact surface of the clutch boss
nut.
• Apply engine oil to the contact sur-
faces of the conical washer.
• Install the conical washer with its
convex surface "a" outward.
• Use the clutch holding tool "3" to
hold the clutch boss.
A. For USA and CDN
B. Except for USA and CDN3. Install:
• Friction plate "1"
• Clutch plate "2"
• Install the clutch plates and friction
plates alternately on the clutch
boss, starting with a friction plate
and ending with a friction plate.
• Apply the engine oil on the friction
plates and clutch plates.
4. Install:
•Bearing "1"
• Washer "2"
• Circlip "3"
To push rod 1 "4".
Apply the engine oil on the bearing
and washer.
5. Install:
• Push rod 2 "1"
• Ball "2"
• Push rod 1 "3"
Apply the engine oil on the push rod
1, 2 and ball.
6. Install:
• Pressure plate "1"7. Install:
• Clutch spring
• Bolt (clutch spring)
Tighten the bolts in stage, using a
crisscross pattern.
8. Install:
• O-ring (clutch cover) "1"
9. Install:
• Clutch cover "1"
• Bolt (clutch cover)
Tighten the bolts in stage, using a
crisscross pattern.
Nut (clutch boss):
75 Nm (7.5 m•kg, 54
ft•lb)
Clutch holding tool:
YM-91042/90890-04086
Bolt (clutch spring):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (clutch cover):
10 Nm (1.0 m•kg, 7.2
ft•lb)

4-32
OIL FILTER ELEMENT AND WATER PUMP
INSTALLING THE RIGHT
CRANKCASE COVER
1. Install:
• Dowel pin "1"
• O-ring "2"
•Collar "3"
• Gasket "4"
Apply the lithium soap base grease
on the O-ring.
2. Install:
• Right crankcase cover "1"
•Bolt "2"
• Apply the engine oil on the impeller
shaft end.
• When installing the crankcase cov-
er onto the crankcase, be sure that
the impeller shaft end "3" aligns
with the balancer end slot "4".
• Tighten the bolts in stage, using a
crisscross pattern.
INSTALLING THE KICKSTARTER
CRANK
1. Install:
• Kickstarter crank "1"
• Washer
• Bolt (kickstarter crank)
Install so that there is a clearance "a"
of 8 mm (0.31 in) or more between
the kickstarter and frame and that the
kickstarter does not contact the
crankcase cover when it is pulled.
INSTALLING THE WATER PUMP
HOUSING
1. Install:
• Dowel pin "1"
• Gasket "2"
2. Install:
• Water pump housing "1"
• Bolt (water pump housing) "2"
• Washer "3"
• Coolant drain bolt "4"3. Install:
• O-ring
• Coolant pipe "1"
• Bolt (radiator pipe) "2"
Apply the lithium soap base grease
on the O-ring.
INSTALLING THE OIL FILTER
ELEMENT
1. Install:
• Oil filter element "1"
• O-ring "2"
• Oil filter element cover "3"
• Bolt (oil filter element cover)
Apply the lithium soap base grease
on the O-ring.
Bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (kickstarter crank):
33 Nm (3.3 m•kg, 24
ft•lb)
Bolt (water pump hous-
ing):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Coolant drain bolt:
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (radiator pipe):
10 Nm (1.0 m•kg, 7.2
ft•lb)
Bolt (oil filter element
cover):
10 Nm (1.0 m•kg, 7.2
ft•lb)

4-44
AC MAGNETO
REMOVING THE ROTOR
1. Remove:
• Nut (rotor) "1"
• Washer
2. Remove:
• Rotor "1"
Use the rotor puller 2.
CHECKING THE AC MAGNETO
1. Inspect:
• Rotor inner surface "a"
• Stator outer surface "b"
Damage → Inspect the crank-
shaft runout and crankshaft bear-
ing.
CHECKING THE WOODRUFF KEY
1. Inspect:
• Woodruff key "1"
Damage → Replace.INSTALLING THE AC MAGNETO
1. Install:
• Stator "1"
• Screw (stator) "2"
• Crankshaft position sensor "3"
• Holder "4"
• Bolt (crankshaft position sensor)
"5"
• Apply the sealant on the grommet
of the AC magneto lead.
• Tighten the screws using the T30
bit.
• Pass the crankshaft position sensor
lead "a" this side of the stator lead
"b".
• Install the holder so that the projec-
tion "c" on the holder contacts the
stopper.
2. Install:
• Woodruff key "1"
• Rotor "2"
• Degrease the contact surfaces of
the tapered portions of the crank-
shaft and rotor.
• When installing the woodruff key,
make sure that its flat surface "a" is
in parallel with the crankshaft center
line "b".
• When installing the rotor, align the
keyway "c" of the rotor with the
woodruff key.
3. Install:
• Washer
• Nut (rotor) "1"
4. Connect:
• AC magneto lead
Refer to "CABLE ROUTING DIA-
GRAM" section in the CHAPTER
2.
5. Install:
• Dowel pin
• Gasket (left crankcase cover)
• Left crankcase cover "1"
• Hose guide (cylinder head breath-
er hose) "2"
• Bolt (left crankcase cover)
Tighten the bolts in stage, using a
crisscross pattern.
Rotor puller:
YM-04151/90890-04151
Screw (stator):
8 Nm (0.8 m•kg,
5.8ft•lb)
Bolt (crankshaft position
sensor):
10 Nm (1.0 m•kg, 7.2
ft•lb)
YAMAHA Bond No. 1215
(ThreeBond
® No. 1215):
90890-85505
Nut (rotor):
65 Nm (6.5 m•kg, 47
ft•lb)
Bolt (left crankcase cov-
er):
10 Nm (1.0 m•kg, 7.2
ft•lb)

5-4
FRONT WHEEL AND REAR WHEEL
2. Install:
• Brake disc "1"
• Bolt (brake disc) "2"
Tighten the bolts in stage, using a
crisscross pattern.
3. Install:
•Collar "1"
• Apply the lithium soap base grease
on the oil seal lip.
• Install the collars with their projec-
tions "a" facing the wheel.
4. Install:
• Wheel
Install the brake disc "1" between the
brake pads "2" correctly.
5. Install:
• Wheel axle "1"
Apply the lithium soap base grease
on the wheel axle.
6. Install:
• Nut (wheel axle) "1"
7. Tighten:
• Bolt (axle holder) "1"
Before tightening the bolt, fit the
wheel axle to the axle holder by strok-
ing the front fork several times with
the front brake applied.
INSTALLING THE REAR WHEEL
1. Install:
• Bearing (right) "1"
• Circlip "2"
• Spacer "3"
• Bearing (left) "4"
• Oil seal "5"
• Apply the lithium soap base grease
on the bearing and oil seal lip when
installing.
• Install the bearing with seal facing
outward.
• Use a socket that matches the out-
side diameter of the race of the
bearing.
• Right side of bearing shall be in-
stalled first.
• Install the oil seal with its manufac-
ture's marks or numbers facing out-
ward.
Do not strike the inner race of the
bearing. Contact should be made
only with the outer race.
Bolt (brake disc):
12 Nm (1.2 m•kg, 8.7
ft•lb)
Nut (wheel axle):
105 Nm (10.5 m•kg, 75
ft•lb)
Bolt (axle holder):
21 Nm (2.1 m•kg, 15
ft•lb)

5-5
FRONT WHEEL AND REAR WHEEL
2. Install:
• Brake disc "1"
• Bolt (brake disc) "2"
Tighten the bolts in stage, using a
crisscross pattern.
3. Install:
• Rear wheel sprocket "1"
• Bolt (rear wheel sprocket) "2"
• Washer (rear wheel sprocket) "3"
• Nut (rear wheel sprocket) "4"
Tighten the nuts in stage, using a
crisscross pattern.
4. Install:
•Collar "1"
Apply the lithium soap base grease
on the oil seal lip.
5. Install:
• Wheel
Install the brake disc "1" between the
brake pads "2" correctly.
6. Install:
• Drive chain "1"
Push the wheel "2" forward and install
the drive chain.
7. Install:
• Left drive chain puller "1"
• Wheel axle "2"
• Install the left drive chain puller, and
insert the wheel axle from left side.
• Apply the lithium soap base grease
on the wheel axle.
8. Install:
• Right drive chain puller "1"
• Washer "2"
• Nut (wheel axle) "3"
Temporarily tighten the nut (wheel
axle) at this point.
9. Adjust:
• Drive chain slack "a"
Refer to "ADJUSTING THE
DRIVE CHAIN SLACK" section in
the CHAPTER 3.
10. Tighten:
• Nut (wheel axle) "1"
• Locknut "2" Bolt (brake disc):
14 Nm (1.4 m•kg, 10
ft•lb)
Nut (rear wheel sprock-
et):
42 Nm (4.2 m•kg, 30
ft•lb)
Drive chain slack:
50–60 mm (2.0–2.4 in)
Nut (wheel axle):
135 Nm (13.5 m•kg, 98
ft•lb)
Locknut:
21 Nm (2.1 m•kg, 15
ft•lb)

6-2
FUEL TANK
REMOVING THE FUEL TANK
1. Extract the fuel in the fuel tank through the fuel tank cap with a
pump.
Be careful not to damage the fuel
pump.
2. Remove: • Fuel pump coupler
Although the fuel has been re-
moved from the fuel tank be care-
ful when removing the fuel hoses,
since there may be fuel remaining
in it.
• Before disconnecting the fuel hose, clean the area around the fuel hose
connector.
• Before removing the fuel hose, place a few rags in the area under
where it will be removed.
• To disconnect the fuel hose from the fuel tank, remove the fuel hose
connector holder "a", and then slide
the fuel hose connector cover.
• Slide the fuel hose connector cover "1" in the direction of the arrow
mark, and press the buttons "2" on
both sides of the connector to re-
move the fuel hose.
• Disconnecting the hose is done by hand. There is no need to use tools.
• To prevent sand, dust, and other
foreign material from entering the
fuel pump, install the included fuel
hose joint cover 1 "3" and fuel hose
joint cover 2 "4" onto the fuel pump
and disconnected fuel hose.
3. Remove:•Fuel tank
Do not set the fuel tank down so that
the installation surface of the fuel
pump is directly under the tank.
REMOVING THE FUEL PUMP
1. Remove:•Fuel pump
Do not drop the fuel pump or give
it a strong shock.
CHECKING THE FUEL PUMP
BODY
1. Check:
• Fuel pump bodyCracks/damage → Replace fuel
pump assembly.
CHECKING THE FUEL PUMP
OPERATION
1. Check: • Fuel pump operationRefer to "CHECKING THE FUEL
PRESSURE" section.
INSTALLING THE FUEL PUMP
1. Install: •Fuel pump
• Fuel pump bracket
•Do not damage th e installation
surfaces of the fuel tank when in-
stalling the fuel pump.
• Before installing the fuel pump,
remove any dirt and other foreign
material from the installation sur-
face on the fuel tank.
• Always use a new fuel pump gas- ket.
• Install the lip on the fuel pump gas- ket upward.
• Install the fuel pump as shown in
the illustration.
• Align the projection "a" on the fuel pump with the slot in the fuel pump
bracket. Align the slot "b" on the fuel
tank damper with the projection "a"
on the fuel pump.
• Tighten the fuel pump bolts in stag- es in a crisscross pattern.
INSTALLING THE FUEL TANK
1. Install:•Fuel hose
•When installing the fuel hose,
make sure that it is securely con-
nected, and that the fuel hose
holders are in the correct posi-
tion, otherwise the fuel hose will
not be properly installed.
• Be sure not to kink or pinch the
fuel hose.
• Insert the fuel hose on the fuel pipe
until you hear a definite "click".
• Slide the fuel hose connector cover
"1" at the fuel hose end in the direc-
tion of the arrow.
• Install the fuel hose connector hold-
er "a".
• Make sure that the fuel hose and fuel pump lead are routed through
the guide on the cover.
Fuel pump bracket bolt
4 Nm (0.4 m•kg, 2.9
ft•lb)