2003 YAMAHA WR 450F timing chain

SPEC

2 - 11
MAINTENANCE SPECIFICATIONS
Part to be tightened Thread size Q’tyTightening torque
Nm m·kg ft·lb
Spark plug M10S
×
1.0 1 13 1.3 9.4
Camshaft cap M6
×
1.0 10 10 1.0 7.2
Cylinder head blind plug screw M12
×
1.0 1 37 3.7 27
Cylinder head (stud bolt) M6
×
1.0 2 7 0.7 5.1
M8
×
1.25 1 15 1.5 11
(bolt) M10
×
1.25 4 Refer to NOTE.*
1

(nut) M6
×
1.0 2 10 1.0 7.2
Cylinder head cover M6
×
1.0 2 10 1.0 7.2
Cylinder M6
×
1.0 1 10 1.0 7.2
Timing chain tensioner M6
×
1.0 2 10 1.0 7.2
Tensioner cap bolt M6
×
1.0 1 7 0.7 5.1
Timing chain guide (rear) M6
×
1.0 2 10 1.0 7.2
Exhaust pipe (nut) M8
×
1.25 1 13 1.3 9.4
(bolt) M8
×
1.25 1 24 2.4 17
Silencer M8
×
1.25 2 35 3.5 25
Silencer clamp M8
×
1.25 1 20 2.0 14
Exhaust pipe protector M6
×
1.0 3 10 1.0 7.2
Spark arrester (for USA) M6
×
1.0 3 10 1.0 7.2
Silencer end pipe (for USA) M6
×
1.0 1 10 1.0 7.2
Carburetor joint clamp (cylinder head side) M5
×
0.8 1 3 0.3 2.2
Carburetor joint clamp (carburetor side) M4
×
0.7 1 3 0.3 2.2
Air filter case M6
×
1.0 2 8 0.8 5.8
Air filter joint clamp M6
×
1.0 1 3 0.3 2.2
Air filter joint and air filter case M5
×
0.8 1 4 0.4 2.9
Throttle cable (pull) M6
×
1.0 1 4 0.4 2.9
Throttle cable (return) M12
×
1.0 1 11 1.1 8.0
Throttle cable cover M5
×
0.8 2 4 0.4 2.9
Hot starter plunger M12
×
1.0 1 2 0.2 1.4
Radiator panel (upper) M6
×
1.0 2 10 1.0 7.2
Radiator M6
×
1.0 6 10 1.0 7.2
Radiator hose clamp M6
×
1.0 8 2 0.2 1.4
Radiator pipe 1, 2 M10
×
1.0 2 10 1.0 7.2
Impeller M8
×
1.25 1 14 1.4 10
Water pump housing cover M6
×
1.0 3 10 1.0 7.2
Coolant drain bolt M6
×
1.0 1 10 1.0 7.2
Oil pump cover M4
×
0.7 1 2 0.2 1.4
Oil pump M6
× 1.0 3 10 1.0 7.2
Engine oil drain bolt (oil filter) M6 × 1.0 1 10 1.0 7.2
Oil filter cover M6 × 1.0 2 10 1.0 7.2
Oil delivery pipe 1 M10 × 1.25 1 20 2.0 14
M8 × 1.25 2 18 1.8 13
Oil delivery pipe 2 M6 × 1.0 1 10 1.0 7.2
Oil hose M6 × 1.0 2 10 1.0 7.2

3 - 21
INSP
ADJ
VALVE CLEARANCE ADJUSTMENT
5. Adjust:
Valve clearance
Adjustment steps:
Loosen the timing chain tensioner cap
bolt.
Remove the timing chain tensioner and
camshaft caps.
NOTE:
Remove the camshaft cap bolts in a criss-
cross pattern from the outside working
inwards.
Remove the camshaft (exhaust 1 and
intake 2).
NOTE:
Attach a wire 3 to the timing chain to pre-
vent it from falling into the crankcase.
Remove the valve lifters 4 and the pads 5.
NOTE:
Place a rag in the timing chain space to
prevent pads from falling into the crank-
case.
Identity each valve lifter and pad position
very carefully so that they can be rein-
stalled in their original place.
Select the proper pad using the pad
selecting table.
Pad rangePad Availability:
25 increments
No. 120
~
No. 2401.20 mm
~
2.40 mmPads are available in
0.05 mm increments
NOTE:
The thickness a of each pad is indicated in
hundreths of millimeters on the pad upper
surface.
1
2
3

3 - 22
INSP
ADJ
Round off the last digit of the installed pad
number to the nearest increment.
Last digit of pad
numberRounded value
0, 1 or 2 0
4, 5 or 6 5
8 or 9 10
EXAMPLE:
Installed pad number = 148
Rounded off value = 150
NOTE:
Pads can only be selected in 0.05 mm incre-
ments.
Locate the rounded-off value and the
measured valve clearance in the chart
“PAD SELECTION TABLE”. The field
where these two coordinates intersect
shows the new pad number to use.
NOTE:
Use the new pad number only as a guide
when verifying the valve clearance adjust-
ment.
Install the new pads 6 and the valve lift-
ers 7.
NOTE:
Apply the engine oil on the valve lifters.
Apply the molybdenum disulfide oil on the
valve stem ends.
Valve lifter must turn smoothly when
rotated with a finger.
Be careful to reinstall valve lifters and
pads in their original place.
Install the camshafts (exhaust and intake),
the timing chain and the camshaft caps.
Refer to “CAMSHAFTS” section in the
CHAPTER 4.
T R..
Bolt (camshaft cap):
10 Nm (1.0 m • kg, 7.2 ft • lb)
VALVE CLEARANCE ADJUSTMENT

3 - 23
INSP
ADJ
6. Install:
All removed parts
NOTE:
Install all removed parts in reversed order of
their removal. Note the following points.
Install the timing chain tensioner.
Refer to “CAMSHAFTS” section in the
CHAPTER 4.
NOTE:
Turn the crankshaft counterclockwise sev-
eral turns so that the installed parts settle
into the right position.
Recheck the valve clearance.
If the clearance is still incorrect, repeat all
the clearance adjustment steps until the
specified clearance is obtained.
VALVE CLEARANCE ADJUSTMENT

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

4 - 22
ENGCAMSHAFTS
CAMSHAFTS
Extent of removal:1 Camshaft removal
Extent of removal Order Part name Q’ty Remarks
CAMSHAFTS REMOVAL
1 Timing plug 1
Refer to “REMOVAL POINTS”. 2 Straight plug 1
3 Tensioner cap bolt 1
4 Timing chain tensioner 1
5 Gasket 1
6 Bolt (camshaft cap) 10
7 Camshaft cap 2
8 Clip 2
9 Exhaust camshaft 1
10 Intake camshaft 1
1

4 - 23
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

4 - 24
ENGCAMSHAFTS
6. Remove:
Clips
Exhaust camshaft 1
Intake camshaft 2
NOTE:
Attach a wire 3 to the timing chain to prevent
it from falling into the crankcase.
1
2
3
INSPECTION
Camshaft
1. Inspect:
Cam lobes
Pitting/scratches/blue discoloration →
Replace.
2. Measure:
Cam lobes length a and b
Out of specification → Replace.
Cam lobes length:
Intake:
a31.200 ~ 31.300 mm
(1.2283 ~ 1.2323 in)
: 31.100 mm
(1.2244 in)
b22.550 ~ 22.650 mm
(0.8878 ~ 0.8917 in)
: 22.450 mm
(0.8839 in)
Exhaust:
a30.950 ~ 31.050 mm
(1.2185 ~ 1.2224 in)
: 30.850 mm
(1.2146 in)
b22.494 ~ 22.594 mm
(0.8856 ~ 0.8895 in)
: 22.394 mm
(0.8817 in)
3. Measure:
Runout (camshaft)
Out of specification → Replace.
Runout (camshaft):
Less than 0.03 mm (0.0012 in)