length YAMAHA YZF-R1SC 2004 User Guide

5-31
VALVES AND VALVE SPRINGSENG
CAUTION:
NOTE:
a. Apply a coarse lapping compound a to the
valve face.
Do not let the lapping compound enter the
gap between the valve stem and the valve
guide.
b. Apply molybdenum disulfide oil onto the
valve stem.
c. Install the valve into the cylinder head.
d. Turn the valve until the valve face and valve
seat are evenly polished, then clean off all of
the lapping compound.
For the best lapping results, lightly tap the valve
seat while rotating the valve back and forth be-
tween your hands.
e. Apply a fine lapping compound to the valve
face and repeat the above steps.
f. After every lapping procedure, be sure to
clean off all of the lapping compound from
the valve face and valve seat.
g. Apply Mechanic’s blueing dye (Dykem) onto
the valve face.
h. Install the valve into the cylinder head.
i. Press the valve through the valve guide and
onto the valve seat to make a clear impres-
sion.
j. Measure the valve seat width
a again. If the
valve seat width is out of specification, reface
and lap the valve seat.
EAS00241
CHECKING THE VALVE SPRINGS
The following procedure applies to all of the
valve springs.
1. Measure:

valve spring free length
a
Out of specification
Replace the valve
spring.
Valve spring free length
Intake valve spring
39.3 mm (1.55 in)
: 37.3 mm (1.47 in)
Exhaust valve spring
39.3 mm (1.55 in)
: 37.3 mm (1.47 in)
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5-32
VALVES AND VALVE SPRINGSENG
2. Measure:

compressed valve spring force
a
Out of specification
Replace the valve
spring.
bInstalled length
Compressed valve spring force
(installed)
Intake valve spring
145.9
167.9 N
(14.88
17.12 kg,
32.80
37.74 lb) at
32.65 mm (1.285 in)
Exhaust valve spring
164.1
188.9 N
(16.73
19.26 kg,
36.89
42.46 lb) at
32.82 mm (12.92 in)
3. Measure:

valve spring tilt
a
Out of specification
Replace the valve
spring.
Spring tilt limit
Intake valve spring
1.7 mm (0.07 in)
Exhaust valve spring
1.7 mm (0.07 in)
EAS00242
CHECKING THE VALVE LIFTERS
The following procedure applies to all of the
valve lifters.
1. Check:

valve lifter
Damage / scratches
Replace the valve lift-
ers and cylinder head.
EAS00245
INSTALLING THE VALVES
The following procedure applies to all of the
valves and related components.
1. Deburr:

valve stem end
(with an oil stone)
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5-53
CLUTCHENG
NOTE:
NOTE:
EAS00282
CHECKING THE CLUTCH SPRINGS
The following procedure applies to all of the
clutch springs.
1. Check:

clutch spring
Damage
Replace the clutch springs as a
set.
2. Measure:

clutch spring free length
a
Out of specification
Replace the clutch
springs as a set.
Clutch spring free length
52.5 mm (2.07 in)
: 49.9 mm (1.96 in)
EAS00284
CHECKING THE CLUTCH HOUSING
1. Check:

clutch housing dogs
Damage / pitting / wear
Deburr the clutch
housing dogs or replace the clutch housing.
Pitting on the clutch housing dogs will cause er-
ratic clutch operation.
2. Check:

bearing
Damage / wear
Replace the bearing and
clutch housing.
EAS00285
CHECKING THE CLUTCH BOSS
1. Check:

clutch boss splines
Damage / pitting / wear
Replace the clutch
boss.
Pitting on the clutch boss splines will cause er-
ratic clutch operation.
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8-22
STARTER MOTORELEC
NOTE: 5. Measure:

brush length
a.
Out of specification
Replace the brushes
as a set.
Brush length wear limit
3.6 mm (0.14 in)
6. Measure:

brush spring force
Out of specification
Replace the brush
springs as a set.
Brush spring force
5.28  7.92 N
(538  808 gf, 18.99  28.48 oz)
7. Check:

gear teeth
Damage / wear
Replace the gear.
EAS00772
ASSEMBLING THE STARTER MOTOR
1. Install:

brush seat
1
Align the slot a on the brush seat with the tab b
in the starter motor rear cover.
2. Install:

armature
1
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