2003 YAMAHA WR 450F clutch

CHAPTER 4
ENGINE
SEAT, FUEL TANK
AND SIDE COVERS
................................. 4-1
EXHAUST PIPE AND SILENCER
............ 4-3
RADIATOR
................................................ 4-5
CARBURETOR
......................................... 4-8
CAMSHAFTS
.......................................... 4-21
CYLINDER HEAD
................................... 4-29
VALVES AND VALVE SPRINGS
........... 4-33
CYLINDER AND PISTON
....................... 4-42
CLUTCH
.................................................. 4-48
OIL FILTER, WATER PUMP
AND CRANKCASE COVER (RIGHT)
.... 4-55
BALANCER
............................................ 4-62
OIL PUMP
............................................... 4-65
KICK AXLE AND SHIFT SHAFT
............ 4-69
AC MAGNETO
AND STARTER CLUTCH
....................... 4-76
ENGINE REMOVAL
................................ 4-83
CRANKCASE AND CRANKSHAFT
....... 4-89
TRANSMISSION, SHIFT CAM
AND SHIFT FORK
.................................. 4-98
CHAPTER 5
CHASSIS
FRONT WHEEL AND REAR WHEEL
...... 5-1
FRONT BRAKE AND REAR BRAKE
..... 5-11
FRONT FORK
......................................... 5-27
HANDLEBAR
.......................................... 5-40
STEERING
.............................................. 5-46
SWINGARM
............................................ 5-52
REAR SHOCK ABSORBER
................... 5-60

GEN
INFO

1 - 1
DESCRIPTION
EC100000
GENERAL INFORMATION
EC110000
DESCRIPTION
1
Clutch lever
2
Hot starter lever
3
“ENGINE STOP” button
4
Trip meter
5
Main switch
6
Lights switch
7
Start switch
8
Front brake lever
9
Throttle grip
0
Radiator cap
A
Fuel tank cap
B
Taillight
C
Kickstarter
D
Fuel tank
E
Headlight
F
Radiator
G
Coolant drain bolt
H
Rear brake pedal
I
Valve joint
J
Fuel cock
K
Cold starter knob
L
Air cleaner
M
Drive chain
N
Shift pedal
O
Oil dipstick
P
Front fork
NOTE:


The machine you have purchased may differ
slightly from those shown in the following.

Designs and specifications are subject to
change without notice.
B
CDE
F
G H
1234
5
6
7
8
9
0 A
IJ
K
L
M N
O P

GEN
INFO
1 - 8
SPECIAL TOOLS
YM-01442, 90890-01442 Fork seal driver
This tool is used when install the fork oil seal.YM-01442 90890-01442
YU-3112-C, 90890-03112 Yamaha pocket tester
Use this tool to inspect the coil resistance, output
voltage and amperage.YU-3112-C 90890-03112
YU-8036-B
90890-03113Inductive tachometer
Engine tachometer
This tool is needed for observing engine rpm.YU-8036-B 90890-03113
YM-33277-A, 90890-03141 Timing light
This tool is necessary for checking ignition timing.YM-33277-A 90890-03141
YM-4019, 90890-04019 Valve spring compressor
This tool is needed to remove and install the valve
assemblies.YM-4019 90890-04019
YM-91042, 90890-04086 Clutch holding tool
This tool is used to hold the clutch when removing or
installing the clutch boss securing nut.YM-91042 90890-04086
YM-4116, 90890-04116
YM-4097, 90890-04097Valve guide remover
Intake 4.5 mm (0.18 in)
Exhaust 5.0 mm (0.20 in)
This tool is needed to remove and install the valve
guide.YM-4116
YM-409790890-04116
90890-04097
YM-4117, 90890-04117
YM-4098, 90890-04098Valve guide installer
Intake
Exhaust
This tool is needed to install the valve guide.YM-4117
YM-409890890-04117
90890-04098
YM-4118, 90890-04118
YM-4099, 90890-04099Valve guide reamer
Intake 4.5 mm (0.18 in)
Exhaust 5.0 mm (0.20 in)
This tool is needed to rebore the new valve guide.YM-4118
YM-4099 90890-04118
90890-04099
Part number Tool name/How to use Illustration

1 - 11
GEN
INFO
CONTROL FUNCTIONS
EC152000
CLUTCH LEVER
The clutch lever 1 is located on the left han-
dlebar; it disengages or engages the clutch.
Pull the clutch lever to the handlebar to disen-
gage the clutch, and release the lever to
engage the clutch. The lever should be pulled
rapidly and released slowly for smooth starts.
EC153000
SHIFT PEDAL
The gear ratios of the constant-mesh 5 speed
transmission are ideally spaced. The gears
can be shifted by using the shift pedal 1 on
the left side of the engine.
EC154000
KICKSTARTER
Rotate the kickstarter 1 away from the
engine. Push the starter down lightly with your
foot until the gears engage, then kick smoothly
and forcefully to start the engine. This model
has a primary kickstarter so the engine can be
started in any gear if the clutch is disengaged.
In normal practices, however, shift to neutral
before starting.
1
EC155001
THROTTLE GRIP
The throttle grip 1 is located on the right han-
dlebar; it accelerates or decelerates the
engine. For acceleration, turn the grip toward
you; for deceleration, turn it away from you.
EC156000
FRONT BRAKE LEVER
The front brake lever 1 is located on the right
handlebar. Pull it toward the handlebar to acti-
vate the front brake.

1 - 15
GEN
INFO
STARTING AND BREAK-IN
STARTING AND BREAK-IN
WARNING
Never start or run the engine in a closed
area. The exhaust fumes are poisonous;
they can cause loss of consciousness and
death in a very short time. Always operate
the machine in a well-ventilated area.
CAUTION:
The carburetor on this machine has a
built-in accelerator pump. Therefore,
when starting the engine, do not operate
the throttle or the spark plug will foul.
Unlike a two-stroke engine, this engine
cannot be kick started when the throttle is
open because the kickstarter may kick
back. Also, if the throttle is open the air/
fuel mixture may be too lean for the
engine to start.
Before starting the machine, perform the
checks in the pre-operation check list.
AIR FILTER MAINTENANCE
According to “AIR FILTER CLEANING” section
in the CHAPTER 3, apply the foam-air-filter oil
or its equivalent to the element. (Excess oil in
the element may adversely affect engine start-
ing.)
STARTING A COLD ENGINE
NOTE:
This model is equipped with an ignition circuit
cut-off system. The engine can be started
under the following conditions.
When the transmission is in neutral.
When the clutch is disengaged with the
transmission in any position. However, it is
recommended to shift into neutral before
starting the engine.
1. Inspect the coolant level.
2. Turn the fuel cock to “ON”.
3. Push the main switch to “ON”.
4. Shift the transmission into neutral.
5. Fully open the cold starter knob 1.
6. Start the engine by pushing the start
switch or by kicking the kickstarter.

SPEC

2 - 2
GENERAL SPECIFICATIONS
Oil capacity:
Engine oil
Periodic oil change 1.0 L (0.88 Imp qt, 1.06 US qt)
With oil filter replacement 1.1 L (0.97 Imp qt, 1.16 US qt)
Total amount 1.2 L (1.06 Imp qt, 1.27 US qt)
Coolant capacity (including all routes): 1.6 L (1.41 Imp qt, 1.69 US qt)
Air filter: Wet type element
Fuel:
Type Premium unleaded gasoline only with a research
octane number of 95 or higher.(Except for ZA)
Premium gasoline (For ZA)
Tank capacity 10 L (2.2 Imp gal, 2.64 US gal)
Reserve 1.2 L (0.26 Imp gal, 0.32 US gal)
Carburetor:
Type FCR MX39
Manufacturer KEIHIN
Spark plug:
Type/manufacturer CR8E/NGK (resistance type)
Gap 0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
Clutch type: Wet, multiple-disc
Transmission:
Primary reduction system Gear
Primary reduction ratio 62/22 (2.818)
Secondary reduction system Chain drive
Secondary reduction ratio 50/14 (3.571)
Transmission type Constant mesh, 5-speed
Operation Left foot operation
Gear ratio: 1st 29/12 (2.416)
2nd 26/15 (1.733)
3rd 21/16 (1.312)
4th 21/20 (1.050)
5th 21/25 (0.840)
Chassis:
Frame type Semi double cradle
Caster angle 27.2˚
Trail 118 mm (4.65 in)
Tire:
Type With tube
Size (front) 80/100-21 51M (USA, CDN, ZA)
90/90-21 54R (EUROPE, AUS, NZ)
Size (rear) 110/100-18 64M (USA, CDN, ZA)
130/90-18 69R (EUROPE, AUS, NZ)
Tire pressure (front and rear) 100 kPa (1.0 kgf/cm
2

, 15 psi)

2

SPEC

2 - 8
MAINTENANCE SPECIFICATIONS
Clutch:
Friction plate thickness 2.92 ~ 3.08 mm
(0.115 ~ 0.121 in)2.8 mm
(0.110 in)
Quantity 9 ----
Clutch plate thickness 1.1 ~ 1.3 mm (0.043 ~ 0.051 in) ----
Quantity 8 ----
Warp limit ---- 0.1 mm
(0.004 in)
Clutch spring free length 48.4 mm (1.91 in) 47.4 mm
(1.87 in)
Quantity 6 ----
Clutch housing thrust clearance 0.10 ~ 0.35 mm
(0.0039 ~ 0.0138 in)----
Clutch housing radial clearance 0.010 ~ 0.044 mm
(0.0004 ~ 0.0017 in)----
Clutch release method Inner push, cam push ----
Shifter:
Shifter type Cam drum and guide bar ----
Guide bar bending limit ---- 0.05 mm
(0.002 in)
Kickstarter:
Type Ratchet type ----
Carburetor:
USAEUROPE,
CDN, AUS, NZ,
ZA
I. D. mark 5TJ1 00 5TJ2 10 ----
Main jet (M.J) #150 #160 ----
Main air jet (M.A.J)ø2.0
←
----
Jet needle - clip position (J.N) OBDUT-4 OBDUQ-4 ----
Cutaway (C.A) 1.5
←
----
Pilot jet (P.J) #45 #48 ----
Pilot air jet (P.A.J) #70 #80 ----
Pilot outlet (P.O)ø0.9
←
----
Pilot screw (example) (P.S) 1-3/4 1-1/2 ----
Bypass (B.P)ø1.0
←
----
Valve seat size (V.S)ø3.8
←
----
Starter jet (G.S) #65
←
----
Leak jet (Acc.P) #70 #50 ----
Float height (F.H) 8 mm (0.31 in)
←
----
Engine idle speed 1,700 ~
1,900 r/min
←
----
Intake vacuum 33.3 ~ 38.7 kPa
(250 ~ 290 mmHg,
9.84 ~ 11.42 inHg)
←
----
Hot starter lever free play 3 ~ 6 mm
(0.12 ~ 0.24 in)
←
---- Item Standard Limit

SPEC
2 - 12
MAINTENANCE SPECIFICATIONS
NOTE:
- marked portion shall be checked for torque tightening after break-in or before each race.
NOTE:
*1: Tighten the cylinder head bolts to 30 Nm (3.0 m · kg, 22 ft · lb) in the proper tightening sequence,
remove and retighten the cylinder head bolts to 20 Nm (2.0 m · kg, 14 ft · lb) in the proper tightening
sequence, and then tighten the cylinder head bolts further to reach the specified angle 180˚ in the
proper tightening sequence.Oil check bolt M6 × 1.0 1 10 1.0 7.2
Oil hose clamp–2 2 0.2 1.4
Clutch cover M6 × 1.0 7 10 1.0 7.2
Crankcase cover (right) M6 × 1.0 10 10 1.0 7.2
Crankcase cover (left) M6 × 1.0 9 10 1.0 7.2
Idle gear cover (starter motor) M6 × 1.0 2 10 1.0 7.2
Crankcase M6 × 1.0 12 12 1.2 8.7
Clutch cable holder M6 × 1.0 1 10 1.0 7.2
Oil drain bolt (crankcase rear) M10 × 1.25 1 20 2.0 14
(crankcase left) M6 × 1.0 1 10 1.0 7.2
Oil drain bolt (frame) M8 × 1.25 1 23 2.3 17
Oil strainer (frame) M18 × 1.5 1 90 9.0 65
Crankcase bearing stopper M6 × 1.0 15 10 1.0 7.2
Drive axle oil seal stopper M6 × 1.0 2 10 1.0 7.2
Ratchet wheel guide M6 × 1.0 2 12 1.2 8.7
Stopper plate M6 × 1.0 2 12 1.2 8.7
Kickstarter M8 × 1.25 1 33 3.3 24
Screw (kickstarter) M6 × 1.0 1 7 0.7 5.1
Starter clutch M6 × 1.0 6 16 1.6 11
Primary drive gear M20 × 1.0 1 75 7.5 54
Clutch boss M20 × 1.0 1 75 7.5 54
Push lever M6 × 1.0 1 10 1.0 7.2
Clutch spring M6 × 1.0 6 8 0.8 5.8
Balancer driven gear M14 × 1.0 1 50 5.0 36
Balancer weight plate M6 × 1.0 3 10 1.0 7.2
Drive sprocket M20 × 1.0 1 75 7.5 54
Drive sprocket cover M6 × 1.0 2 8 0.8 5.8
Shift pedal M6 × 1.0 1 12 1.2 8.7
Shift guide M6 × 1.0 2 10 1.0 7.2
Stopper lever M6 × 1.0 1 10 1.0 7.2
Segment M8 × 1.25 1 30 3.0 22 Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb