2014 YAMAHA YZ450F Owners Manual

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
5-63
10Crankshaft1
For assembly, reverse the disassemble pro-cedure.
Separating the crankcase
Order Part name Q’ty Remarks
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
5-67
EAS1SL1283
CRANKSHAFT ASSEMBLY AND BALANCER SHAFT
Removing the crankshaft assembly and balancer shaft
OrderPart nameQ’tyRemarks
CrankcaseSeparate.Refer to “CRANKCASE” on page 5-62.
TransmissionRefer to “TRANSMISSION” on page 5-70.
1Balancer shaft1
2Crankshaft assembly1
For installation, reverse the removal proce-dure.
1
2

CRANKSHAFT ASSEMBLY AND BALANCER SHAFT
5-68
EAS1SL1284REMOVING THE BALANCER SHAFT
1. Remove:
• Balancer shaft “1”
TIP
Remove the balancer shaft with its flat side “a”
facing the crankshaft.
EAS1SL1285REMOVING THE CRANKSHAFT ASSEMBLY
1. Remove:
• Crankshaft assembly “1”
TIP
Remove the crankshaft assembly by using the
crankcase separating tool “2”.
EAS1SL1286
CHECKING THE CRANKSHAFT ASSEMBLY
1. Measure:
• Crankshaft runout
Out of specification  Replace the crank-
shaft, bearing or both.
TIP
Turn the crankshaft slowly.
2. Measure:
• Big end side clearance D “a”
Out of specification  Replace the big end
bearing, crankshaft pin, or connecting rod.
3. Measure:
• Crankshaft width A “a”
Out of specification  Replace the crank-
shaft.
Crankcase separating tool
90890-04152
YU-A9642
1
a
2
1
Runout limit C
0.030 mm (0.0012 in)
Big end side clearance D
0.150–0.450 mm (0.0059–0.0177
in)
Width A
61.95–62.00 mm (2.439–2.441 in)

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