head YAMAHA WR 450F 2003 Owner's Manual

3 - 58
INSP
ADJ
ADJUSTING THE HEADLIGHT BEAMS
5. Install:
Headlight bulb
Secure the new headlight bulb with the
headlight bulb holder.
CAUTION:
Avoid touching the glass part of the head-
light bulb to keep it free form oil, otherwise
the transparency of the glass, the life of the
bulb and the luminous flux will be
adversely affected. If the headlight bulb
gets soiled, thoroughly clean it with a cloth
moistened with alcohol or lacquer thinner.
6. Attach:
Headlight bulb holder
7. Install:
Headlight bulb holder cover
8. Install:
Headlight
Refer to “SEAT, FUEL TANK AND
SIDE COVERS” section in the CHAP-
TER 4.
New
T R..7 Nm (0.7 m · kg, 5.1 ft · lb)
ADJUSTING THE HEADLIGHT BEAMS
1. Adjust:
Headlight beam (vertically)
Adjusting steps:
Turn the adjusting screw 1 in direction a
or b.
Direction a Headlight beam is raised.
Direction b Headlight beam is lowered.

4 - 1
ENG

EC400000
ENGINE
EC4R0000
SEAT, FUEL TANK AND SIDE COVERS
Extent of removal:
1
Seat removal
2
Fuel tank removal
3
Side covers removal
4
Headlight removal
Extent of removal Order Part name Q’ty Remarks
Preparation for removal
SEAT, FUEL TANK AND SIDE
COVERS REMOVAL
Turn the fuel cock to “OFF”.
Disconnect the fuel hose.
1 Seat 1
2 Air scoop (left and right) 2
3 Fitting band 1 Remove on fuel tank side.
4 Bolt (fuel tank) 2
5 Fuel tank 1
6 Side cover (left) 1
Refer to “REMOVAL POINTS”.
7 Side cover (right) 1
8 Headlight coupler 1
9 Headlight 1
13
2
3
4

SEAT, FUEL TANK AND SIDE COVERS

4 - 19
ENGCARBURETOR
Accelerator pump timing adjustment
Adjustment steps:
NOTE:
In order for the throttle valve height a to
achieve the specified value, tuck under the
throttle valve plate 1 the rod 2 etc. with
the same outer diameter as the specified
value.
Throttle valve height:
3.1 mm (0.122 in)
Fully turn in the accelerator pump adjust-
ing screw 3.
Check that the link lever 4 has free play
b by pushing lightly on it.
Gradually turn out the adjusting screw
while moving the link lever until it has no
more free play.
Carburetor installation
1. Install:
Carburetor joint 1
NOTE:
Install the projection a on the cylinder head
between the carburetor joint slots b.
T R..3 Nm (0.3 m · kg, 2.2 ft · lb)
2. Install:
Carburetor 1
NOTE:
Install the projection a between the carburetor
joint slots.
3. Install:
Hot starter plunger 1
1
T R..2 Nm (0.2 m · kg, 1.4 ft · lb)

4 - 21
ENGCAMSHAFTS
CAMSHAFTS
CYLINDER HEAD COVER
Extent of removal:1 Cylinder head cover removal
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD COVER
REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Carburetor Refer to “CARBURETOR” section.
1 Spark plug 1
2 Engine upper bracket (right) 1
3 Engine upper bracket (left) 1
4 Cylinder head breather hose 1
5 Oil tank breather hose 1
6 Bolt (cylinder head cover) 2
7 Cylinder head cover 1
8 Gasket 1
9 Timing chain guide (upper) 1
1

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ENGCAMSHAFTS
REMOVAL POINTS
Camshaft
1. Remove:
Timing plug 1
Straight plug 2
2. Align:
“I” mark
With stationary pointer.
Checking steps:
Turn the crankshaft counterclockwise with
a wrench.
Align the “I” mark a on the rotor with the
stationary pointer b on the crankcase
cover. When the “I” mark is aligned with
the stationary pointer, the piston is at the
Top Dead Center (T.D.C.).
NOTE:
In order to be sure that the piston is at Top
Dead Center, the punch mark c on the
exhaust camshaft and the punch mark d
on the intake camshaft must align with the
cylinder head surface, as shown in the
illustration.
If there is no clearance, rotate the crank-
shaft counterclockwise one turn.
1
2
b
a
3. Loosen:
Tensioner cap bolt 1
4. Remove:
Timing chain tensioner 2
5. Remove:
Bolt (camshaft cap) 1
Camshaft caps 2
NOTE:
Remove the bolts (camshaft cap) in a criss-
cross pattern, working from the outside in.
CAUTION:
The bolts (camshaft cap) must be removed
evenly to prevent damage to the cylinder
head, camshafts or camshaft caps.
1
2
1
2

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ENGCAMSHAFTS
4. Measure:
Camshaft-to-cap clearance
Out of specification → Measure cam-
shaft journal diameter.
Camshaft-to-cap clearance:
0.020 ~ 0.054 mm
(0.0008 ~ 0.0021 in)
: 0.08 mm (0.003 in)
Measurement steps:
Install the camshaft onto the cylinder
head.
Position a strip of Plastigauge® 1 onto the
camshaft.
Install the circlip, dowel pins and camshaft
caps.
T R..
Bolt (camshaft cap):
10 Nm (1.0 m • kg, 7.2 ft • lb)
NOTE:
Tighten the bolts (camshaft cap) in a criss-
cross pattern from innermost to outer
caps.
Do not turn the camshaft when measuring
clearance with the Plastigauge®.
Remove the camshaft caps and measure
the width of the Plastigauge
® 1.
5. Measure:
Camshaft journal diameter a
Out of specification → Replace the
camshaft.
Within specification → Replace cam-
shaft case and camshaft caps as a set.
Camshaft sprocket
1. Inspect:
Camshaft sprocket 1
Wear/damage → Replace the camshaft
assembly and timing chain as a set.
Camshaft journal diameter:
21.967 ~ 21.980 mm
(0.8648 ~ 0.8654 in)

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ENGCAMSHAFTS
Fit the timing chain 3 onto both camshaft
sprockets and install the camshafts on the
cylinder head.
NOTE:
The camshafts should be installed onto the
cylinder head so that the exhaust cam
sprocket punch mark c and the intake cam
sprocket punch mark d align with the sur-
face of the cylinder head.
CAUTION:
Do not turn the crankshaft during the
camshaft installation. Damage or
improper valve timing will result.
Install the clips and camshaft caps 4.
T R..
Bolt (camshaft cap):
10 Nm (1.0 m • kg, 7.2 ft • lb)
NOTE:
Apply the engine oil on the thread and con-
tact surface of the bolts (camshaft cap) 5.
Tighten the bolts (camshaft cap) in a criss-
cross pattern.
CAUTION:
The bolts (camshaft cap) must be tight-
ened evenly, or damage to the cylinder
head, camshaft caps, and camshaft will
result.
5
4
E
2. Install:
Timing chain tensioner
Installation steps:
While pressing the tensioner rod lightly
with fingers, use a thin screwdriver and
wind the tensioner rod up fully clockwise.

4 - 28
ENG
With the rod fully wound and the chain
tensioner UP mark a facing upward,
install the gasket 1 and the chain ten-
sioner 2, and tighten the bolt 3 to the
specified torque.
T R..
Bolt (timing chain tensioner):
10 Nm (1.0 m • kg, 7.2 ft • lb)
Release the screwdriver, check the ten-
sioner rod to come out and tighten the
gasket 4 and the cap bolt 5 to the speci-
fied torque.
T R..
Tensioner cap bolt:
7 Nm (0.7 m • kg, 5.1 ft • lb)
5
4New
3. Turn:
Crankshaft
Counterclockwise several turns
4. Check:
Rotor “I” mark
Align with the crankcase stationary
pointer.
Camshaft match marks
Align with the cylinder head surface.
Out of alignment → Adjust.
CAMSHAFTS

4 - 29
ENGCYLINDER HEAD
CYLINDER HEAD
CYLINDER HEAD
Extent of removal:1 Cylinder head removal
NOTE:
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.
Extent of removal Order Part name Q’ty Remarks
CYLINDER HEAD REMOVAL
Preparation for removal Seat and fuel tank Refer to “SEAT, FUEL TANK AND SIDE
COVERS” section.
Exhaust pipe and silencer Refer to “EXHAUST PIPE AND
SILENCER” section.
Radiator Refer to “RADIATOR” section.
Carburetor Refer to “CARBURETOR” section.
Camshaft Refer to “CAMSHAFTS” section.
1 Oil delivery pipe 1
2 Nut 2
3* Bolt (L = 150 mm) 2
Refer to NOTE.
4* Bolt (L = 160 mm) 2
5 Cylinder head 1
6 Gasket 1
7 Dowel pin 2
8 Timing chain guide (front) 1
1

4 - 30
ENGCYLINDER HEAD
INSPECTION
Cylinder head
1. Eliminate:
Carbon deposits (from the combustion
chambers)
Use a rounded scraper.
NOTE:
Do not use a sharp instrument to avoid dam-
aging or scratching:
Spark plug threads
Valve seats
2. Inspect:
Cylinder head
Scratches/damage → Replace.
3. Measure:
Cylinder head warpage
Out of specification → Resurface.
Cylinder head warpage:
Less than 0.05 mm (0.002 in)
Warpage measurement and resurface-
ment steps:
Place a straightedge and a feeler gauge
across the cylinder head.
Use a feeler gauge to measure the
warpage.
If the warpage is out of specification,
resurface the cylinder head.
Place a 400 ~ 600 grit wet sandpaper on
the surface plate, and resurface the head
using a figure-eight sanding pattern.
NOTE:
To ensure an even surface rotate the cylin-
der head several times.