2014 YAMAHA YZ450F oil

AC MAGNETO
5-59
EAS1SL1272
AC MAGNETO
Removing the AC magneto
OrderPart nameQ’tyRemarks
Engine oilDrain.Refer to “CHANGING THE ENGINE OIL” on page 3-15.
SeatRefer to “GENERAL CHASSIS” on page 4-1.
Air scoop (left)Refer to “GENERAL CHASSIS” on page 4-1.
1AC magneto leadDisconnect.
2Crankshaft position sensor lead1Disconnect.
3Shift pedal1
4Left crankcase cover1
5Gaskets1
6Dowel pin2
7Holder1
8Stator assembly1
9Rotor1
10Woodruff key1
For installation, reverse the removal proce-dure.
110
2
4 7 5 8 3
96
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R.
8 Nm (0.8 mkgf, 5.8 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
10 Nm (1.0 mkgf, 7.2 ftIbf)T.R.
65 Nm (6.5 mkgf, 47 ftIbf)T.R.
New
LT
6
LT
LT

CRANKCASE
5-62
EAS1SL1277
CRANKCASE
Separating the crankcase
OrderPart nameQ’tyRemarks
EngineRefer to “ENGINE REMOVAL” on page 5-1.
PistonRefer to “CYLINDER AND PISTON” on page 5-32.
BalancerRefer to “OIL PUMP AND BALANCER GEAR” on page 5-54.
Kick shaft assemblyRefer to “KICKSTATER” on page 5-46.
SegmentRefer to “SHIFT SHAFT” on page 5-49.
StatorRefer to “AC MAGNETO” on page 5-59.
1Timing chain guide (exhaust side)1
2Timing chain guide stopper plate1
3Timing chain1
4Bolt [L = 45 mm (1.77 in)]6
5Bolt [L = 65 mm (2.56 in)]4
6Bolt [L = 75 mm (2.95 in)]2
7Right crankcase1
8Left crankcase1
9Dowel pin2
10 Nm (1.0 m•kgf, 7.2 ft•Ibf)T.R.
12 Nm (1.2 m•kgf, 8.7 ft•Ibf)T.R.
12 Nm (1.2 m•kgf, 8.7 ft•Ibf)T.R.
12 Nm (1.2 m•kgf, 8.7 ft•Ibf)T.R.
3
1 5
2
6410 55
4
4
446
97
8
9
LT

CRANKCASE
5-64
Removing the bearing and oil seal
OrderPart nameQ’tyRemarks
TransmissionRefer to “TRANSMISSION” on page 5-70.
Shift cam and shift forkRefer to “TRANSMISSION” on page 5-70.
1Circlip1
2Oil seals3
3Bearing11
For installation, reverse the removal proce-dure.
LT
LT
LT
LT
LT
1
22
3
3
33
3
3
3 3
33
New
NewLT

CRANKCASE
5-65
EAS1SL1278DISASSEMBLING THE CRANKCASE
1. Separate:
• Right crankcase
• Left crankcase
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Remove the crankcase bolts.
TIP
Loosen each bolt 1/4 of a turn at a time and af-
ter all the bolts are loosened, remove them.
b. Remove the right crankcase “1.”
TIP
• Place the crankcase with its left side down-
ward and split it by inserting a screwdriver tip
into the splitting slit “a” in the crankcase.
• Lift the right crankcase horizontally while light-
ly patting the crankcase splitting slit and the
engine mounting boss using a soft hammer,
and leave the crankshaft and the transmission
with the left crankcase.
ECA33DD041
NOTICE
Use soft hammer to tap on the case half.
Tap only on reinforced portions of case. Do
not tap on gasket mating surface. Work
slowly and carefully. Make sure the case
halves separate evenly. If the cases do not
separate, check for a remaining case bolt or
fitting. Do not force.
c. Remove the dowel pins and O-ring.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS1SL1279REMOVING THE CRANKCASE BEARING
1. Remove:
• Bearing “1”
TIP
• Remove the bearing from the crankcase by
pressing its inner race.
• Do not use the removed bearing.
EAS1SL1280CHECKING THE TIMING CHAIN, TIMING
CHAIN GUIDE, OIL STRAINER
1. Check:
• Timing chain
Stiffness  Replace the camshaft sprocket,
timing chain and crankshaft sprocket as a
set.
2. Check:
• Timing chain guide
Damage/wear  Replace
EAS1SL1281CHECKING THE CRANKCASE
1. Wash:
• Crankcase
TIP
• Wash the crankcase in a mild solvent.
• Remove any remaining gasket from the
crankcase mating surface.
1
a

CRANKCASE
5-66
2. Check:
• Crankcase
Crack/damage  Replace.
• Oil delivery passages
Obstruction  Blow out with compressed
air.
EAS1SL1282ASSEMBLING THE CRANKCASE
1. Install:
• Bearing cover plate
TIP
• Install the bearing by pressing its outer race
parallel.
• To prevent the bearing cover plate screw
(crankshaft) “1” from becoming loose, crimp
the screw head periphery “a” into the concave
“b” using a punch etc. In so doing, take care
not to damage the screwdriver receiving hole
in the screw.
2. Apply:
• Sealant
(to the crankcase mating surface)
3. Install:
• Dowel pin “1”
• Crankcase (to the left crankcase)
TIP
• Apply the lithium-soap-based grease on the
O-ring.
• Fit the right crankcase onto the left crankcase.
Tap lightly on the case with soft hammer.
• When installing the crankcase, the connecting
rod should be positioned at top dead center
(TDC).
• Tighten the bolts in a crisscross pattern in two
(2) stages, with 1/4 turn each.
Bearing cover plate
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
LOCTITE®
Bearing cover plate (crankshaft)
18 Nm (1.8 m·kgf, 13 ft·lbf)
Three Bond No.1215®
90890-85505
T R..
a
b
1
1
Crankcase bolt
12 Nm (1.2 m·kgf, 8.7 ft·lbf)
3. 45 mm (1.77 in)
4. 65 mm (2.56 in)
5. 75 mm (2.95 in)
T R..
5
3
5
3
3 3 45 4
3

CRANKSHAFT ASSEMBLY AND BALANCER SHAFT
5-69
4. Check:
• Crankshaft sprocket “1”
Damage  Replace the crankshaft.
5. Check:
• Crankshaft journal oil passage
Obstruction  Blow out with compressed
air.
EAS1SL1287INSTALLING THE CRANKSHAFT ASSEM-
BLY
1. Install:
• Crankshaft assembly
TIP
Install the crankshaft assembly with the crank-
shaft installer pot “1”, crankshaft installer bolt
“2”, adapter (M12) “3” and spacer “4”.
ECA13970
NOTICE
• To avoid scratching the crankshaft and to
ease the installation procedure, lubricate
the oil seal lips with lithium-soap-based
grease.
• In order to prevent the crankshaft seizure,
apply molybdenum disulfide grease.
TIP
Hold the connecting rod at top dead center
(TDC) with one hand while turning the nut of the
crankshaft installer bolt with the other. Turn the
crankshaft installer bolt until the crankshaft as
-
sembly bottoms against the bearing.
Crankshaft installer pot
90890-01274
Installing pot
YU-90058
Crankshaft installer bolt
90890-01275
Bolts
YU-90060
Adapter (M12)
90890-01278
Adapter #3
YU-90063
Spacer (crankshaft installer)
90890-04081
Pot spacer
YM-91044
1

TRANSMISSION
5-72
CHECKING THE SHIFT DRUM ASSEMBLY
1. Check:
• Shift drum groove
Damage/scratches/wear  Replace the
shift drum assembly.
• Shift drum segment “1”
Damage/wear  Replace the shift drum as-
sembly.
EAS1SL1292CHECKING THE TRANSMISSION
1. Measure:
• Main axle runout
(with a centering device and dial gauge “1”)
Out of specification  Replace the main ax-
le.
2. Measure:
• Drive axle runout
(with a centering device and dial gauge “1”)
Out of specification  Replace the drive ax-
le.
3. Check:
• Transmission gears
Blue discoloration/pitting/wear  Replace
the defective gear (s).
• Transmission gear dogs
Cracks/damage/rounded edges  Replace
the defective gear (s).
4. Check:
• Transmission gear movement
Rough movement  Replace the defective
gear (s).
EAS1SL1293INSTALLING THE TRANSMISSION
1. Install:
• 5th pinion gear (21T) “1”
• 3rd pinion gear (20T) “2”
• Collar “3”
• 4th pinion gear (22T) “4”
• 2nd pinion gear (15T) “5”
(to the main axle “6”)
TIP
Before installation, apply molybdenum disulfide
oil to the inner and end surface of the idler gear
and to the inner surface of the sliding gear, then
install.
Main axle runout limit
0.08 mm (0.0032 in)
Drive axle runout limit
0.08 mm (0.0032 in)
34
2
1
6
5
M

TRANSMISSION
5-73
2. Install:
• Collar “1”
• 2nd wheel gear (23T) “2”
• 4th wheel gear (24T) “3”
• 3rd wheel gear (26T) “4”
• 5th wheel gear (20T) “5”
• Collar “6”
• 1st wheel gear (27T) “7”
• O-rings “8”
(to the drive axle “9”)
TIP
• Before installation, apply molybdenum disul-
fide oil to the inner and end surface of the idler
gear and to the inner surface of the sliding
gear, then install.
• Apply the lithium-soap-based grease on the
O-ring.
3. Install:
• Washer “1”
• Circlip “2”
TIP
• Be sure the circlip sharp-edged corner “a” is
positioned opposite side to the washer and
gear “b”.
• Install the circlip with its ends “c” settled even-
ly on the spline crests.
4. Install:
• Collar “1”
TIP
• Apply the lithium soap base grease on the oil
seal lip.
• When installing the collar into the crankcase,
pay careful attention to the crankcase oil seal
lip.
5. Install:
• Main axle “1”
• Drive axle “2”
TIP
• Install to the left crankcase simultaneously.
• Apply engine oil to the main axle and the drive
axle bearing.
New
298
3
4
5
6
7
New
M
LS
1
New
21
2
ab
cc
1
2
EE