2014 YAMAHA YZ450F Owners Manual

IMPORTANT INFORMATION
1-11
GASKETS, OIL SEALS AND O-RINGS
1. When overhauling the engine, replace all
gaskets and O-rings. All gasket surfaces, oil
seal lips, and O-rings must be cleaned so
that there may be no dust on them.
2. During assembly, always apply proper oil to
bearings and proper grease to oil seal lips
before installation.
EAS1SL1026LOCK WASHERS/PLATES AND COTTER
PINS
After removal, replace lock washers/plates “1”
and cotter pins with new ones. After the bolt or
nut has been tightened to specification, firmly
bend the lock tabs along a flat of the bolt or nut.
EAS1SL1027BEARINGS AND OIL SEALS
Install bearings “1” and oil seals “2” with their
manufacturer’s marks or size symbols facing
outward. During installation of an oil seal, make
sure that its main lip faces the oil chamber (the
target to be sealed). Before installation, always
apply a light coat of grease to the oil seal lip.
ECA13300
NOTICE
Do not spin a bearing with compressed air
because this will damage the bearing sur
-
faces.
EAS1SL1028CIRCLIPS
When assembling parts, always use new cir-
clips. During installation of a circlip, make sure
that the edge “2” of the circlip “1” is positioned
opposite to the force “3” that the circlip re
-
ceives. Install the circlip with its end aligned
with the center of the spline, without opening
the circlip more than necessary.
1. Oil
2. Lip
3. Spring
4. Grease

BASIC SERVICE INFORMATION
1-12
EAS1SL1029
BASIC SERVICE INFORMATION
EAS1SL1030ELECTRICAL SYSTEM
Electrical parts handlingECA16620
NOTICE
Handle electrical components with special
care, and do not subject them to strong
shocks.
ECA16630
NOTICE
Electrical components are very sensitive to
and can be damaged by static electricity.
Therefore, never touch the terminals and be
sure to keep the contacts clean.
Checking the electrical systemECA14371
NOTICE
Never insert the tester probes into the cou-
pler terminal slots. Always insert the probes
from the opposite end “a” of the coupler,
taking care not to loosen or damage the
leads.
ECA16640
NOTICE
For waterproof couplers, never insert the
tester probes directly into the coupler.
When performing any checks using a water
-
proof coupler, use the specified test har-
ness or a suitable commercially available
test harness.
Checking the connections
Check leads, couplers, and connectors for
stains, rust, moisture, etc.
1. Disconnect:
• Lead
• Coupler
• ConnectorECA16780
NOTICE
• When disconnecting a coupler, release the
coupler lock, hold both sections of the
coupler, and then disconnect the coupler.
• There are many types of coupler locks;
therefore, be sure to check the type of cou
-
pler lock before disconnecting the cou-
pler.
a

BASIC SERVICE INFORMATION
1-13
ECA16790
NOTICE
When disconnecting a connector, do not
pull the leads. Hold both sections of the
connector, and then disconnect the con
-
nector.
2. Check:
• Lead
• Coupler
• Connector
Moisture  Dry with compressed air.
Rust/stains  Connect and disconnect sev-
eral times.
3. Check:
• All connections
Loose connection  Connect properly.
TIP
• If the pin “1” on the terminal is flattened, bend
it up.
• After disassembling or assembling a coupler,
pull on the leads to make sure that they are in
-
stalled securely.
4. Connect:
• Lead
• Coupler
• Connector
TIP
• When connecting a coupler or a connector,
make sure that both terminals are connected
securely.
• Make sure all connections are tight.
1

BASIC SERVICE INFORMATION
1-14
5. Check:
• No continuity
TIP
• If there is no continuity, clean the terminals.
• When checking the wire harness, perform
steps (1) to (4).
• As a quick remedy, use a contact revitalizer
available at most part stores.
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C

SPECIAL TOOLS
1-15
EAS1SL1031
SPECIAL TOOLS
The following special tools are required for accurate and complete adjustment and assembly. Using
the correct special tool will help prevent damage caused by the use of improper tools or improvised
techniques. The shape and tool number used for the special tool differ by country, so two types are
provided. Refer to the list provided to avoid errors when placing an order.
TIP
• For U.S.A. and Canada, use tool number starting with “YM-,” “YU-,” or “ACC-.”
• For others, use tool number starting with “90890-.”
Tool name/Part numberHow to useIllustration
Dial gauge & stand set
90890-01252
Dial gauge set
YU-03097-B
This tool is used to check
parts for runout or bend.
Crankshaft installer pot
90890-01274
Installing pot
YU-90058
This tool is used to install the
crankshaft.
Crankshaft installer bolt
90890-01275
Bolts
YU-90060
This tool is used to install the
crankshaft.
Adapter (M12)
90890-01278
Adapter #3
YU-90063
This tool is used to install the
crankshaft.
Piston pin puller set
90890-01304
Piston pin puller
YU-01304
This tool is used to remove
the piston pin.

SPECIAL TOOLS
1-16
Radiator cap tester
90890-01325
Mityvac cooling system tester
kit
YU-24460-A
This tool is used to check the
radiator and the radiator cap.
Radiator cap tester adapter
90890-01352
Pressure tester adapter
YU-33984
This tool is used to check the
radiator and the radiator cap.
Steering nut wrench
90890-01403
Exhaust flange nut wrench
YU-A9472
This tool is used to remove or
tighten the steering nut.
Cap bolt wrench
90890-01500
YM-01500
This tool is used to remove or
tighten the base valve.
Cap bolt ring wrench
90890-01501
YM-01501
This tool is used to loosen or
tighten the damper assem
-
bly.
Fork seal driver
90890-01502
YM-A0948
This tool is used to install the
oil seal of the front fork.
Spoke nipple wrench (6–7)
90890-01521
YM-01521
This tool is used to tighten the
spoke.
Tool name/Part number How to use Illustration

SPECIAL TOOLS
1-17
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
This tool is used to measure
the voltage, current, and re
-
sistance of electrical compo-
nents.
Timing light
90890-03141
YU-03141
This tool is used to measure
the ignition timing.
Pressure gauge
90890-03153
YU-03153
This tool is used to measure
the fuel pressure.
Yamaha diagnostic tool
90890-03215
This tool is used to check er-
ror codes or carry out self-di-
agnosis.
Fuel pressure adapter
90890-03186
YM-03186
This tool is used to mount the
pressure gauge.
Test harness S-pressure
sensor (3P)
90890-03207
YU-03207
This tool is used to check the
throttle position sensor input
voltage.
FI diagnostic tool sub-lead
90890-03212
YU-03212
This tool is used to connect
the Yamaha diagnostic tool
to a battery.
Valve guide remover & in-
staller set (ø5.5)
90890-04016
This tool is used to replace
the valve guide.
Valve guide remover (5.5
mm)
YM-01122
Valve guide installer (5.5
mm)
YM-04015
Valve guide reamer (5.5 mm)
YM-01196
Tool name/Part number How to use Illustration

SPECIAL TOOLS
1-18
Spacer (crankshaft installer)
90890-04081
Pot spacer
YM-91044
This tool is used to install the
crankshaft.
Clutch holder
90890-04086
YM-91042
This tool is used to hold the
clutch when removing or in
-
stalling the clutch boss secur-
ing nut.
Valve lapper
90890-04101
Valve lapping tool
YM-A8998
This tool is used to remove
the valve lifter or lap the
valve.
Valve spring compressor
90890-04019
YM-04019
This tool is used to discon-
nect or connect the valve and
the valve spring.
Valve spring compressor
adapter 22 mm
90890-04108
YM-04108
This tool is used to discon-
nect or connect the valve and
the valve spring.
Rotor puller
90890-04151
YM-04151
This tool is used to remove
the rotor.
Tool name/Part number How to use Illustration
YM-91044
YM-04019