2003 YAMAHA YZ450F lock

ILLUSTRATED SYMBOLS
(Refer to the illustration)
Illustrated symbols
1
to
7
are designed as
thumb tabs to indicate the chapter’s number
and content.
1
General information
2
Specifications
3
Regular inspection and adjustments
4
Engine
5
Chassis
6
Electrical
7
Tuning
Illustrated symbols
8
to
D
are used to identify
the specifications appearing in the text.
8
With engine mounted
9
Special tool
0
Filling fluid
A
Lubricant
B
Tightening
C
Specified value, Service limit
D
Resistance (
Ω
), Voltage (V), Electric current (A)
Illustrated symbols
E
to
H
in the exploded
diagrams indicate grade of lubricant and loca-
tion of lubrication point.
E
Apply engine oil
F
Apply molybdenum disulfide oil
G
Apply lightweight lithium-soap base grease
H
Apply molybdenum disulfide grease
Illustrated symbols
I
to
J
in the exploded
diagrams indicate where to apply a locking
agent and where to install new parts.
IApply locking agent (LOCTITE®)
JUse new one 12
34
56
78
90
AB
CD
EF
GH
IJ
GEN
INFOSPEC
INSP
ADJENG
CHAS–+ELEC
TUN
T R..
EM
BM
New

1 - 4
GEN
INFO

IMPORTANT INFORMATION
EC132000
ALL REPLACEMENT PARTS
1. We recommend to use Yamaha genuine
parts for all replacements. Use oil and/or
grease recommended by Yamaha for
assembly and adjustment.
EC133000
GASKETS, OIL SEALS AND O-RINGS
1. All gaskets, oil seals, and O-rings should
be replaced when an engine is over-
hauled. All gasket surfaces, oil seal lips,
and O-rings must be cleaned.
2. Properly oil all mating parts and bearings
during reassembly. Apply grease to the
oil seal lips.
EC134000
LOCK WASHERS/PLATES AND COTTER
PINS
1. All lock washers/plates
1
and cotter pins
must be replaced when they are
removed. Lock tab(s) should be bent
along the bolt or nut flat(s) after the bolt
or nut has been properly tightened.
EC135001
BEARINGS AND OIL SEALS
1. Install the bearing(s)
1
and oil seal(s)
2
with their manufacturer’s marks or num-
bers facing outward. (In other words, the
stamped letters must be on the side
exposed to view.) When installing oil
seal(s), apply a light coating of light-
weight lithium base grease to the seal
lip(s). Oil the bearings liberally when
installing.
CAUTION:

Do not use compressed air to spin the
bearings dry. This causes damage to the
bearing surfaces.

1 - 16
GEN
INFO
DECOMPRESSION LEVER ADJUSTMENT
1. Check:
Decompression lever free play
2. Adjust:
Decompression lever free play
FOR PROPER USE
CAUTION:
Never use the decompression lever after
the engine is started. The engine may be
damaged if you use the decompression
lever while it is running.
NOTE:
Refer to “STARTING AND BREAK-IN” for
starting except when “The engine fails to start.”
The engine fails to start
Pull the decompression lever to the handlebar,
and while holding the lever, kick the kick
starter 10 to 20 times to clear the engine of the
rich mixture.Checking steps:
Remove the timing plug.
Turn the crankshaft counterclockwise to
align the T.D.C. mark a on the rotor with
the align mark b on the crankcase cover
when piston is at T.D.C. on compression
stroke.
Check the free play c.
Free play:
3 ~ 5 mm (0.12 ~ 0.20 in)
Adjustment steps:
Loosen the locknut 1.
Turn the adjuster 2 in or out until the
adjustment is suitable.
Tighten the locknut.
CAUTION:
After the adjustment, start the engine
and make sure that the engine does not
stop when the handlebars are turned
fully both ways. If the decompression
cable is too tense, the engine will stop by
the decompression system.
2 1 c
DECOMPRESSION LEVER

1 - 23
GEN
INFO
CLEANING AND STORAGE
EC1B0000
CLEANING AND STORAGE
EC1B1000
CLEANING
Frequent cleaning of your machine will
enhance its appearance, maintain good overall
performance, and extend the life of many com-
ponents.
1. Before washing the machine, block off
the end of the exhaust pipe to prevent
water from entering. A plastic bag
secured with a rubber band may be used
for this purpose.
2. If the engine is excessively greasy, apply
some degreaser to it with a paint brush.
Do not apply degreaser to the chain,
sprockets, or wheel axles.
3. Rinse the dirt and degreaser off with a
garden hose; use only enough pressure
to do the job.
CAUTION:
Excessive hose pressure may cause water
seepage and contamination of wheel bear-
ings, front forks, brakes and transmission
seals. Many expensive repair bills have
resulted from improper high pressure
detergent applications such as those avail-
able in coin-operated car washers.
4. After the majority of the dirt has been
hosed off, wash all surfaces with warm
water and a mild detergent. Use an old
toothbrush to clean hard-to-reach places.
5. Rinse the machine off immediately with
clean water, and dry all surfaces with a
soft towel or cloth.
6. Immediately after washing, remove
excess water from the chain with a paper
towel and lubricate the chain to prevent
rust.
7. Clean the seat with a vinyl upholstery
cleaner to keep the cover pliable and
glossy.

1 - 24
GEN
INFO
CLEANING AND STORAGE
8. Automotive wax may be applied to all
painted or chromed surfaces. Avoid com-
bination cleaner-waxes, as they may con-
tain abrasives.
9. After completing the above, start the
engine and allow it to idle for several min-
utes.
EC1B2001
STORAGE
If your machine is to be stored for 60 days or
more, some preventive measures must be
taken to avoid deterioration. After cleaning the
machine thoroughly, prepare it for storage as
follows:
1. Drain the fuel tank, fuel lines, and the
carburetor float bowl.
2. Remove the spark plug, pour a table-
spoon of SAE 10W-30 motor oil in the
spark plug hole, and reinstall the plug.
With the engine stop switch pushed in,
kick the engine over several times to coat
the cylinder walls with oil.
3. Remove the drive chain, clean it thor-
oughly with solvent, and lubricate it.
Reinstall the chain or store it in a plastic
bag tied to the frame.
4. Lubricate all control cables.
5. Block the frame up to raise the wheels off
the ground.
6. Tie a plastic bag over the exhaust pipe
outlet to prevent moisture from entering.
7. If the machine is to be stored in a humid
or salt-air environment, coat all exposed
metal surfaces with a film of light oil. Do
not apply oil to rubber parts or the seat
cover.
NOTE:
Make any necessary repairs before the
machine is stored.

SPEC

2 - 6
MAINTENANCE SPECIFICATIONS
Valve spring:
Free length IN 37.03 mm (1.46 in) 35.17 mm
(1.38 in)
EX 37.68 mm (1.48 in) 35.79 mm
(1.41 in)
Set length (valve closed) IN 27.87 mm (1.10 in) ----
EX 27.38 mm (1.08 in) ----
Compressed force
(installed) IN 111.3 ~ 127.9 N at 27.87 mm
(11.3 ~ 13.0 kg at 27.87 mm,
24.91 ~ 28.66 lb at 1.10 in)----
EX 127.4 ~ 146.4 N at 27.38 mm
(13.0 ~ 14.9 kg at 27.38 mm,
28.66 ~ 32.85 lb at 1.08 in)----
Tilt limit IN ---- 2.5˚/ 1.61 mm
(2.5˚/0.063 in)
EX ---- 2.5˚/1.65 mm
(2.5˚/0.065 in)
Direction of winding
(top view) IN Clockwise ----
EX Clockwise ----
Piston:
Piston to cylinder clearance 0.040 ~ 0.065 mm
(0.0016 ~ 0.0026 in)0.1 mm
(0.004 in)
Piston size “D”94.945 ~ 94.960 mm
(3.738 ~ 3.739 in)----
Measuring point “H”8 mm (0.315 in) ----
Piston off-set 1 mm (0.0394 in) ----
Piston pin bore inside diameter 18.004 ~ 18.015 mm
(0.7088 ~ 0.7093 in)18.045 mm
(0.7104 in)
Piston pin outside diameter 17.991 ~ 18.000 mm
(0.7083 ~ 0.7087 in)17.971 mm
(0.7075 in) Item Standard Limit
*
H
D

SPEC
2 - 15
MAINTENANCE SPECIFICATIONS
NOTE:
1. First, tighten the ring nut approximately 38 Nm (3.8 m • kg, 27 ft • lb) by using the ring nut
wrench, then loosen the ring nut one turn.
2. Retighten the ring nut 7 Nm (0.7 m • kg, 5.1 ft • lb). Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Handle crown and outer tube M8 × 1.25 4 23 2.3 17
Under bracket and outer tube M8 × 1.25 4 20 2.0 14
Handle crown and steering shaft M24 × 1.0 1 145 14.5 105
Handlebar holder (upper) M8 × 1.25 4 28 2.8 20
Steering ring nut M28 × 1.0 1 Refer to NOTE.
Front fork and cap bolt M48 × 1.0 2 30 3.0 22
Front fork and base valve M30 × 1.0 2 55 5.5 40
Cap bolt and damper rod (front fork) M12 × 1.25 2 29 2.9 21
Bleed screw (front fork) and cap bolt M5 × 0.8 2 1 0.1 0.7
Front fork and protector M6 × 1.0 6 10 1.0 7.2
Front fork and brake hose holder M6 × 1.0 2 10 1.0 7.2
Front fork and hose cover M8 × 1.25 1 16 1.6 11
Front fork and hose cover M6 × 1.0 1 7 0.7 5.1
Throttle cable cap M5 × 0.8 2 4 0.4 2.9
Clutch lever holder mounting M5 × 0.8 2 4 0.4 2.9
Clutch lever mounting M6 × 1.0 1 2 0.2 1.4
Hot starter lever holder mounting M5 × 0.8 2 4 0.4 2.9
Front brake master cylinder and bracket M6 × 1.0 2 9 0.9 6.5
Front brake master cylinder cap M4 × 0.7 2 2 0.2 1.4
Brake lever mounting (bolt) M6 × 1.0 1 6 0.6 4.3
Brake lever mounting (nut) M6 × 1.0 1 6 0.6 4.3
Brake lever position locknut M6 × 1.0 1 5 0.5 3.6
Cable guide (front brake hose) and guide stay M5 × 0.8 1 4 0.4 2.9
Front brake hose union bolt (master cylinder) M10 × 1.25 1 30 3.0 22
Front brake hose union bolt (caliper) M10 × 1.25 1 30 3.0 22
Front brake caliper and front fork M8 × 1.25 2 23 2.3 17
Brake caliper (front and rear) and pad pin plug M10 × 1.0 1 3 0.3 2.2
Brake caliper (front and rear) and pad pin M10 × 1.0 1 18 1.8 13
Brake caliper (front and rear) and bleed screw M8 × 1.25 1 6 0.6 4.3
Front wheel axle and nut M16 × 1.5 1 105 10.5 75
Front wheel axle holder M8 × 1.25 4 23 2.3 17
Front brake disc and wheel hub M6 × 1.0 6 12 1.2 8.7
Rear brake disc and wheel hub M6 × 1.0 6 14 1.4 10
Brake pedal mounting M8 × 1.25 1 26 2.6 19
Rear brake master cylinder and frame M6 × 1.0 2 11 1.1 8.0
Rear brake master cylinder cap M4 × 0.7 2 2 0.2 1.4
Rear brake hose union bolt (caliper) M10 × 1.25 1 30 3.0 22
Rear brake hose union bolt (master cylinder) M10 × 1.25 1 30 3.0 22

SPEC
2 - 16
MAINTENANCE SPECIFICATIONS
NOTE:
- marked portion shall be checked for torque tightening after break-in or before each race.Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Rear wheel axle and nut M20 × 1.5 1 125 12.5 90
Driven sprocket and wheel hub M8 × 1.25 6 42 4.2 30
Nipple (spoke)–72 3 0.3 2.2
Disc cover and rear brake caliper M6 × 1.0 2 7 0.7 5.1
Protector and rear brake caliper M6 × 1.0 2 7 0.7 5.1
Chain puller adjust bolt and locknut M8 × 1.25 2 16 1.6 11
Engine mounting:
Engine upper bracket and frame M10 × 1.25 2 55 5.5 40
Engine lower bracket and frame M8 × 1.25 4 34 3.4 24
Engine and frame (front) M10 × 1.25 1 65 6.5 47
Engine and frame (upper) M10 × 1.25 1 55 5.5 40
Engine and frame (lower) M10 × 1.25 1 69 6.9 50
Engine guard (lower) M8 × 1.25 1 23 2.3 17
Engine skid plate mounting M6 × 1.0 6 10 1.0 7.2
CDI unit bracket mounting M6 × 1.0 1 10 1.0 7.2
Pivot shaft and nut M16 × 1.5 1 85 8.5 61
Relay arm and swingarm M14 × 1.5 1 80 8.0 58
Relay arm and connecting rod M14 × 1.5 1 80 8.0 58
Connecting rod and frame M14 × 1.5 1 80 8.0 58
Rear shock absorber and frame M10 × 1.25 1 56 5.6 40
Rear shock absorber and relay arm M10 × 1.25 1 53 5.3 38
Rear frame and frame (upper) M8 × 1.25 1 32 3.2 23
Rear frame and frame (lower) M8 × 1.25 2 29 2.9 21
Swingarm and brake hose holder M5 × 0.8 4 1 0.1 0.7
Swingarm and patch M4 × 0.7 4 2 0.2 1.4
Drive chain tensioner mounting (upper) M8 × 1.25 1 19 1.9 13
Drive chain tensioner mounting (lower) M8 × 1.25 1 20 2.0 14
Chain support and swingarm M6 × 1.0 3 7 0.7 5.1
Seal guard and swingarm M5 × 0.8 4 6 0.6 4.3
Fuel tank mounting M6 × 1.0 2 10 1.0 7.2
Fuel tank and fuel cock M6 × 1.0 2 7 0.7 5.1
Fuel tank and seat set bracket M6 × 1.0 1 7 0.7 5.1
Fuel tank and hooking screw (fitting band) M6 × 1.0 1 7 0.7 5.1
Fuel tank and fuel tank bracket M6 × 1.0 4 7 0.7 5.1
Seat mounting M8 × 1.25 2 23 2.3 17
Side cover mounting M6 × 1.0 2 7 0.7 5.1
Air scoop and fuel tank M6 × 1.0 6 4 0.4 2.9
Air scoop and radiator panel (lower) M6 × 1.0 2 4 0.4 2.9
Front fender mounting M6 × 1.0 4 7 0.7 5.1
Rear fender mounting (front) M6 × 1.0 2 7 0.7 5.1
Rear fender mounting (rear) M6 × 1.0 2 10 1.0 7.2
Number plate M6 × 1.0 1 7 0.7 5.1