light YAMAHA YZ450F 2016 User Guide

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

VALVES AND VALVE SPRINGS
5-32
5. To fasten the valve cotters onto the valve
stem, lightly tap the valve tip with a soft-face
hammer.
ECA
NOTICE
Hitting the valve tip with excessive force
could damage the valve.
6. Lubricate:
• Adjusting pad “1”
• Valve lifter “2”
7. Install:
• Adjusting pad
• Valve lifter
TIP
• Check that the valve lifter turns smoothly
when rotated with your finger.
• Make sure that the valve lifter and the adjust-
ing pad are reinstalled in their original posi-
tions.
E
1 2

CRANKCASE
5-67
EASB111277DISASSEMBLING THE CRANKCASE
1. Separate:
• Right crankcase
• Left crankcase
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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.
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EASB111278REMOVING 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.
EASB111279CHECKING 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
1
a

CRANKCASE
5-68
EASB111280CHECKING THE CRANKCASE
1. Wash:
• Crankcase
TIP
• Wash the crankcase in a mild solvent.
• Remove any remaining gasket from the
crankcase mating surface.
2. Check:
• Crankcase
Crack/damage  Replace.
• Oil delivery passages
Obstruction  Blow out with compressed
air.
EASB111281ASSEMBLING 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 pins “1”
• Crankcase “2”
(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
1
12

TRANSMISSION
5-73
EASB111288REMOVING THE TRANSMISSION
1. Remove:
• Long shift fork guide bar “1”
• Short shift fork guide bar “2”
• Shift cam “3”
• Shift fork 3 “4”
• Shift fork 2 “5”
• Shift fork 1 “6”
• Main axle “7”
• Drive axle “8”
• Collar “9”
TIP
• Remove assembly with the collar “9” installed
to the crankcase.
• Make a note of the position of each part. Pay
particular attention to the location and direc-
tion of shift forks.
• Remove the main axle and the drive axle all
together by tapping the drive axle lightly with
a soft hammer.
EASB111289
CHECKING THE SHIFT FORKS
1. Check:
• Shift fork cam follower “1”
• Shift fork pawl “2”
Bends/damage/scoring/wear  Replace the
shift fork.
2. Check:
• Shift fork guide bar
Roll the shift fork guide bar on a flat surface.
Bends  Replace.
EWA
WARNING
Do not attempt to straighten a bent shift fork
guide bar.
3. Check:
• Shift fork movement
(along the shift fork guide bar)
Rough movement  Replace the shift forks
and shift fork guide bar as a set.
1
4
62
5
3
8
7
9

TRANSMISSION
5-76
6. Install:
• Shift fork 1 (L) “1”
• Shift fork 2 (C) “2”
• Shift fork 3 (R) “3”
• Shift cam “4”
(to the main axle and the drive axle)
TIP
• Apply engine oil to the shift fork grooves.
• Apply engine oil to the shift cam groove and
the bearing contact surface.
• Mesh the shift fork 1 (L) with the 4th wheel
gear “5” and 3 (R) with the 5th wheel gear “7”
on the drive axle.
• Mesh the shift fork 2 (C) with the 3rd pinion
gear “6” on the main axle.7. Install:
• Long shift fork guide bar “1”
• Short shift fork guide bar “2”
• Spring “3”
TIP
• Screw the spring into the shift fork guide bar
lightly beforehand.
• Apply the engine oil on the shift fork guide
bars.
8. Check:
• Operation of shift cam and shift fork
• Transmission operation
Unsmooth operation  Repair.
3
12
EE
E
2 13
E

IGNITION SYSTEM
8-5
The launch control indicator light fail to blink.
TIP
Before troubleshooting, remove the following part(s):
1. Seat
2. Air scoop (left)8. Check the ignition system wire har-
ness.
Refer to “CIRCUIT DIAGRAM” on
page 8-2.NG 
Repair or replace the wire harness.
OK 
Replace the ECU.
1. Check the launch control switch
coupler connections.NG 
Reconnect.
OK 
2. Check the neutral switch coupler
connections.NG 
Reconnect.
OK 
3. Check the launch control switch.
Refer to “CHECKING THE
SWITCHES” on page 8-38.NG 
Replace the launch control switch.
OK 
4. Check the neutral switch.
Refer to “CHECKING THE NEU-
TRAL SWITCH” on page 8-46.NG 
Replace the neutral switch.
OK 
5. Check the fuel ignition system wire
harness.
Refer to “CIRCUIT DIAGRAM” on
page 8-2.NG 
Repair or replace the wire harness.
OK 
Replace the ECU.

FUEL INJECTION SYSTEM
8-28
Fault code 50
Symptom ECU: faulty ECU memory
Fail-safe systemUnable to start engine
Unable to drive vehicle
Diagnostic code No.—
Diagnostic tool display—
Procedure—
Or-
derProbable cause of malfunc-
tion and checkMaintenance job Reinstatement method
1 Faulty ECU Replace the ECU. Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Check that the fault code
number is not displayed.
Fault code Waiting for connection
Symptom No communication signal is received from the ECU.
Fail-safe systemAble to start engine (Unable when ECU is malfunctioning)
Able to drive vehicle (Unable when ECU is malfunctioning)
Diagnostic code No.—
Diagnostic tool display—
Procedure—
Or-
derProbable cause of malfunc-
tion and checkMaintenance job Reinstatement method
1 Connection of Yamaha diag-
nostic tool coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
2 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
3 Wire harness continuity. Open or short circuit  Re-
place the wire harness.
light green–light greenTurn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.

FUEL INJECTION SYSTEM
8-29
4 Yamaha diagnostic tool mal-
functionReplace the Yamaha diag-
nostic tool.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
5 Faulty ECU Replace the ECU.
Fault code Er-2
SymptomSignals from the ECU cannot be received within the specified
period of time.
Fail-safe systemAble to start engine
Able to drive vehicle
Diagnostic code No.—
Diagnostic tool display—
Procedure—
Or-
derProbable cause of malfunc-
tion and checkMaintenance job Reinstatement method
1 Connection of Yamaha diag-
nostic tool coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
2 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
3 Wire harness continuity. Open or short circuit  Re-
place the wire harness.
light green–light greenTurn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
4 Yamaha diagnostic tool mal-
functionReplace the Yamaha diag-
nostic tool.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
5 Faulty ECU Replace the ECU. Fault code Waiting for connection
Symptom No communication signal is received from the ECU.

FUEL INJECTION SYSTEM
8-30
Fault code Er-3
Symptom Data from the ECU cannot be received correctly.
Fail-safe systemAble to start engine
Able to drive vehicle
Diagnostic code No.—
Diagnostic tool display—
Procedure—
Or-
derProbable cause of malfunc-
tion and checkMaintenance job Reinstatement method
1 Connection of Yamaha diag-
nostic tool coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
2 Connection of wire harness
ECU coupler.
Check the locking condition
of the coupler.
Disconnect the coupler, and
check the pins (for bent or
broken terminals and locking
condition of the pins).Improperly connected 
Connect the coupler secure-
ly, or repair/replace the wire
harness.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
3 Wire harness continuity. Open or short circuit  Re-
place the wire harness.
light green–light greenTurn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
4 Yamaha diagnostic tool mal-
functionReplace the Yamaha diag-
nostic tool.Turn “ON” the switch on the
FI diagnostic tool sub-lead.
Fault code No. is not dis-
played  Repair is finished.
Fault code No. is displayed 
Go to next order.
5 Faulty ECU Replace the ECU.