2016 YAMAHA YZ450F Owners Manual

CAMSHAFT
5-14
EASB111207REMOVING THE CAMSHAFT
1. Remove:
• Timing mark accessing screw “1”
• Crankshaft end accessing screw “2”
2. Align:
• Alignment mark
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a. Turn the crankshaft counterclockwise with a
wrench.
b. Align the top dead center (TDC) mark “a” on
the rotor with the alignment mark “b” on the
crankcase cover.
TIP
Align the alignment mark “c” on the exhaust
camshaft sprocket and the alignment mark “d”
on the intake camshaft sprocket with the edge
of the cylinder head.
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3. Remove:
• Timing chain tensioner cap bolt “1”
• Timing chain tensioner “2”
•Gaskets
4. Remove:
• Bolt (camshaft cap) “1”
• Camshaft cap “2”
• Clip “3”
TIP
• Remove the bolts (camshaft cap) in a criss-
cross pattern, working from the outside in.
• In order to prevent the clip from falling into the
crankcase, remove the camshaft cap.
ECA33DD027
NOTICE
The bolts (camshaft cap) must be removed
evenly to prevent damage to the cylinder
head, camshafts or camshaft caps.
1
2
b
a
dc
1 2
1
2
3

CAMSHAFT
5-15
5. Remove:
• Exhaust camshaft “1”
• Intake camshaft “2”
TIP
Attach a wire “3” to the timing chain to prevent
it from falling into the crankcase.
EASB111208CHECKING THE CAMSHAFT
1. Check:
• Camshaft lobes
Blue discoloration/pitting/scratches  Re-
place the camshaft.
2. Measure:
• Camshaft lobe dimensions “A” and “B”
Out of specification  Replace the cam-
shaft.3. Measure:
• Camshaft runout
Out of specification  Replace.
4. Measure:
• Camshaft-journal-to-camshaft-cap clear-
ance
Out of specification  Measure the cam-
shaft journal diameter. Camshaft lobe dimensions
Lobe height (Intake)
37.630–37.730 mm (1.4815–
1.4854 in)
Limit
37.620 mm (1.4811 in)
Base circle diameter (Intake)
27.950–28.050 mm (1.1004–
1.1043 in)
Limit
27.940 mm (1.0000 in)
Lobe height (Exhaust)
33.870–33.970 mm (1.3335–
1.3374 in)
Limit
33.860 mm (1.3331 in)
Base circle diameter (Exhaust)
24.711–24.811 mm (0.9729–
0.9768 in)
Limit
24.701mm (0.9725 in)
1
2
3
Camshaft runout limit
0.030 mm (0.0012 in)
Camshaft-journal-to-camshaft-
cap clearance
0.028–0.062 mm (0.0011–0.0024
in)

CAMSHAFT
5-16
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a. Install the camshaft into the cylinder head.
b. Position a strip of Plastigauge® “1” onto the
camshaft journal as shown.
c. Install the dowel pins and the camshaft
caps.
TIP
• Tighten the camshaft cap bolts in a crisscross
pattern from innermost to outer caps.
• Do not turn the camshaft when measuring the
camshaft journal-to-camshaft cap clearance.
d. Remove the camshaft caps and then mea-
sure the width of the Plastigauge® “1”.
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5. Measure:
• Camshaft journal diameter “a”
Out of specification  Replace the cam-
shaft.
Within specification  Replace the cylinder
head and the camshaft caps as a set.
EASB111209CHECKING THE TIMING CHAIN AND CAM-
SHAFT SPROCKET
1. Check:
• Timing chain “1”
Damage/stiffness  Replace the timing
chain and camshaft as a set.
2. Check:
• Camshaft sprocket
More than 1/4 tooth wear “a”  Replace the
camshaft and the timing chain as a set.
EASB111210CHECKING THE TIMING CHAIN TENSION-
ERS
1. Check:
• Timing chain tensioner
Crack/damage  Replace.
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a. While pressing the tensioner rod lightly with
your fingers, use a thin screwdriver “1” to
wind the tensioner rod up fully clockwise.
b. When releasing the screwdriver by pressing
lightly with your fingers, make sure that the
tensioner rod will come out smoothly. Camshaft cap bolts
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Camshaft journal diameter
21.959–21.972 mm (0.8645–
0.8650 in)
1
T R..
1
a. 1/4 tooth
b. Correct
1. Timing chain roller
2. Camshaft sprocket
a
b1
2

CAMSHAFT
5-17
c. If not, replace the tensioner assembly.
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EASB111211CHECKING THE DECOMPRESSION SYS-
TEM
1. Check:
• Decompression system
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a. Check that the decompressor cam “1”
moves smoothly.
b. Check that the decompressor lever pin “2”
projects from the camshaft.
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EASB111212
INSTALLING THE CAMSHAFTS
1. Install:
• Exhaust camshaft “1”
• Intake camshaft “2”
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a. Turn the crankshaft counterclockwise with a
wrench.
TIP
• Apply molybdenum disulfide oil to the cam-
shafts.
• Apply the engine oil on the decompression
system.
• Fill the cylinder head with engine oil up to the
tops “a” of the valve lifters.
b. Align the top dead center (TDC) mark “a” on
the rotor with the alignment mark “b” on the
crankcase cover.
c. Fit the timing chain “3” onto both camshaft
sprockets and install the camshafts on the
cylinder head.
1
2
a
aa
b
a

CAMSHAFT
5-18
TIP
Make sure that the alignment mark “c” on the
exhaust camshaft sprocket and the alignment
mark “d” on the intake camshaft sprocket are
aligned with the edge of the cylinder head.
ECA33DD029
NOTICE
Do not turn the crankshaft during the cam-
shaft installation. Damage or improper
valve timing will result.
d. Install the clips, the camshaft caps and the
bolts (camshaft cap).
TIP
• Before installing the clips, cover the cylinder
head with a clean cloth to prevent the clips
from coming off into the cylinder head cavity.
• Apply the engine oil to the threads and con-
tact surfaces.
• Tighten the bolts to the specified torque in two
or three steps in the proper tightening se-
quence as shown.
ECA33DD030
NOTICE
The bolts (camshaft cap) must be tightened
evenly, or damage to the cylinder head,
camshaft caps, and camshaft will result.
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2. Install:
• Timing chain tensioner
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a. While pressing the tensioner rod lightly with
your fingers, use a thin screwdriver to wind
the tensioner rod up fully clockwise.
b. With the tensioner rod fully wound and the
chain tensioner UP mark “a” facing upward,
install the gasket “1”, the timing chain ten-
sioner “2”, and the gasket “3”, and tighten
the bolt “4”.
c. Release the screwdriver, check that the ten-
sioner rod comes out smoothly, and tighten
the gasket “5” and the cap bolt “6”.
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Bolt (camshaft cap)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
c 3
d
T R..
3
4
8
7
15
26
E
Bolt (timing chain tensioner)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Tensioner cap bolt
6 Nm (0.6 m·kgf, 4.3 ft·lbf)
T R..
T R..
6 5

CAMSHAFT
5-19
3. Turn:
• Crankshaft
Counterclockwise several turns.
4. Check:
• Top dead center (TDC) mark on the rotor
Align with the crankcase alignment mark.
• Camshaft match marks
Align with the cylinder head surface.
Out of alignment  Adjust.
5. Install:
• Timing chain guide (top side) “1”
• Cylinder head cover gasket “2”
• Cylinder head cover “3”
• Bolt (cylinder head cover) “4”
TIP
Before installation, apply the sealant to the cyl-
inder head cover gasket.
6. Install:
• Cylinder head breather hose
• Spark plugBolt (cylinder head cover)
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Three Bond No.1215®
90890-85505
Spark plug
13 Nm (1.3m·kgf, 9.4 ft·lbf)
T R..
4
4
4
3
21
T R..

CYLINDER HEAD
5-20
EASB111213
CYLINDER HEAD
Removing the cylinder head
Order Part name Q’ty Remarks
Refer to “INSTALLING THE CYLINDER
HEAD” on page 5-23.
Seat Refer to “GENERAL CHASSIS” on page 4-1.
Side cover (left/right) Refer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left / right) Refer to “GENERAL CHASSIS” on page 4-1.
Fuel tank Refer to “FUEL TANK” on page 7-1.
Exhaust pipe and silencer Refer to “ENGINE REMOVAL” on page 5-1.
Radiator hose Disconnect.
Coolant temperature sensor coupler Disconnect.
Throttle body Refer to “THROTTLE BODY” on page 7-5.
Camshaft Refer to “CAMSHAFT” on page 5-12.
Upper engine bracket Refer to “ENGINE REMOVAL” on page 5-1.
1 Bolt (cylinder head) 2
2 Bolt (cylinder head) 4
3 Cylinder head 1
4 Cylinder head gasket 1
7 66
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.
15 Nm (1.5 m kgf, 11 ft Ibf)T.R.
*
20 Nm (2.0 mkgf, 14 ftIbf)T.
R.
30 Nm (3.0 mkgf, 22 ftIbf)
*

CYLINDER HEAD
5-21
5 Timing chain guide (intake side) 1
6 Oil check bolt 2
7 Oil passage plug 1
For installation, reverse the removal proce-
dure.
Removing the cylinder head
Order Part name Q’ty Remarks
7 66
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.
10 Nm (1.0 m kgf, 7.2 ft Ibf)T.R.
15 Nm (1.5 m kgf, 11 ft Ibf)T.R.
*
20 Nm (2.0 mkgf, 14 ftIbf)T.
R.
30 Nm (3.0 mkgf, 22 ftIbf)