YAMAHA YZF-R7 1999 Owners Manual

4 - 19
ENGCYLINDER HEAD
EB402102
REMOVING THE CYLINDER HEAD
1. Remove:
• cylinder head bolts
• cylinder head nuts
NOTE:
• Loosen each bolt and nut 1/2 of a turn
at a time, in stages and in a crisscross
pattern. After all of the bolts and nuts
are fully loosened, remove them.
• Loosen the bolts and nuts in decreas-
ing numerical order (refer to the num-
bers in the illustration).
EB402402
CHECKING THE CYLINDER HEAD
1. Eliminate:
• combustion chamber carbon deposits
(with a rounded scraper)
NOTE:
Do not use a sharp instrument to avoid
damaging or scratching:
• spark plug bore threads
• valve seats
2. Check:
• cylinder head
Damage/scratches ® Replace.
• cylinder head water jacket
Mineral deposits/rust ® Eliminate.

4 - 20
ENGCYLINDER HEAD
3. Measure:
• cylinder head warpage
Out of specification ® Resurface the
cylinder head.
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a. Place a straightedge 1 and a thick-
ness gauge 2 across the cylinder
head.
b. Measure the warpage.
c. If the limited is exceeded, resurface
the cylinder head as follows.
d. Place a 400 ~ 600 grit wet sandpaper
on the surface plate and resurface the
cylinder head using a figure-eight
sanding pattern.
NOTE:
To ensure an even surface, rotate the
cylinder head several times.
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Maximum cylinder head
warpage
0.06 mm (0.0024 in)
EB402702
INSTALLING THE CYLINDER HEAD
1. Install:
• cylinder head
• cylinder head nut (1 ~ 10)
• cylinder head bolt (11, 12)
NOTE:
• Lubricate the cylinder head nuts with
engine oil.
• Tighten the cylinder head nuts and
bolts in two stages and in a crisscross
pattern.
• Tighten the nuts and bolts in numeri-
cal order (refer to the numbers in the
illustration).
T R..1st. 20 Nm (2.0 m · kg, 14 ft · lb)
2nd. 50 Nm (5.0 m · kg, 36 ft · lb)
T R..12 Nm (1.2 m · kg, 8.7 ft · lb)

ENG
4 - 21
VALVES AND VALVE SPRINGS
EB403000
VALVES AND VALVE SPRINGS
Order Job/Part Q’ty Remarks
Removing the valves and valve
springsRemove the parts in the order listed.
Cylinder head Refer to “CYLINDER HEAD”.
1 Intake valve lifter 12
2 Intake valve pad 12
3 Intake valve cotter 24
4 Intake valve upper spring seat 12
5 Intake outer valve spring 12
6 Intake inner valve spring 12
7 Intake valve oil seal 12
8 Intake valve lower spring seat 12
9 Intake valve 12
10 Intake valve guide 12

ENG
4 - 22
VALVES AND VALVE SPRINGS
Order Job/Part Q’ty Remarks
11 Exhaust valve lifter 8
12 Exhaust valve pad 8
13 Exhaust valve cotter 16
14 Exhaust valve upper spring seat 8
15 Exhaust outer valve spring 8
16 Exhaust inner valve spring 8
17 Exhaust valve oil seal 8
18 Exhaust valve lower spring seat 8
19 Exhaust valve 8
20 Exhaust valve guide 8
For installation, reverse the removal
procedure.

4 - 23
ENGVALVES AND VALVE SPRINGS
EB403100
REMOVING THE VALVES
The following procedure applies to all of
the valves and related components.
NOTE:
Before removing the internal parts of the
cylinder head (e.g., valves, valve
springs, valve seats), make sure that the
valves properly seal.
1. Remove:
• valve lifter 1
• valve pad 2
NOTE:
Make a note of the position of each
valve lifter and valve pad so that they
can be reinstalled in their original place.
2. Check:
• valve
(for leakage)
Leakage at the valve seat ® Check the
valve face, valve seat, and valve seat
width.
Refer to “CHECKING THE VALVE
SEATS”.
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a. Pour a clean solvent a into the intake
and exhaust ports.
b. Check that the valves properly seal.
NOTE:
There should be no leakage at the valve
seat 1.
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4 - 24
ENGVALVES AND VALVE SPRINGS
3. Remove:
• valve cotters 1
NOTE:
Remove the valve cotters by compress-
ing the valve spring with the valve spring
compressor 2 and attachment 3.
Valve spring compressor
90890-04019
Attachment
(for the intake valve)
90890-04114
(for the exhaust valve)
90890-04108
4. Remove:
• upper spring seat 1
• valve springs 2
• lower spring seat 3
• valve 4
• oil seal 5
NOTE:
Identify the position of each part very
carefully so that it can be reinstalled in
its original place.
EB403400
CHECKING THE VALVES AND VALVE
GUIDES
The following procedure applies to all of
the valves and valve guides.
1. Measure:
• valve stem-to-valve guide clearance
Out of specification ® Replace the
valve guide.Valve stem-to-valve guide clearance =
Valve guide inside diameter a –
Valve stem diameter b
Valve stem-to-valve guide
clearance
Intake
0.005 ~ 0.029 mm
(0.0002 ~ 0.0011 in)
: 0.06 mm (0.0024 in)
Exhaust
0.010 ~ 0.034 mm
(0.0004 ~ 0.0013 in)
: 0.07 mm (0.0028 in)

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ENGVALVES AND VALVE SPRINGS
2. Replace:
• valve guide
NOTE:
To ease valve guide removal and instal-
lation, and to maintain the correct fit,
heat the cylinder head to 100 ˚C (212 ˚F)
in an oven.
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a. Remove the valve guide with a valve
guide remover 1.
b. Install the new valve guide with the
valve guide installer 2 and valve
guide remover 1.
c. After installing the valve guide, bore
the valve guide with a valve guide
reamer 3 to obtain the proper valve
stem-to-valve guide clearance.
NOTE:
After replacing the valve guide, reface
the valve seat.
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Valve guide remover
Intake (4.0 mm)
90890-04111
Valve guide installer
Intake (4.0 mm)
90890-04112
Valve guide reamer
Intake
90890-04113
3. Eliminate:
• carbon deposits
(from the valve face and valve seat)
4. Check:
• valve face
Pitting/wear ® Grind the valve face.
• valve stem end
Mushroom shape or diameter larger
than the body of the valve stem ®
Replace the valve.

4 - 26
ENGVALVES AND VALVE SPRINGS
5. Measure:
• valve margin thickness a
Out of specification ® Replace the
valve.
6. Measure:
• valve stem runout
Out of specification ® Replace the
valve.
NOTE:
• When installing a new valve, always
replace the valve guide.
• If the valve is removed or replaced,
always replace the oil seal.
Valve margin thickness
Intake
0.9 ~ 1.2 mm
(0.028 ~ 0.047 in)
Exhaust
1.0 ~ 1.3 mm
(0.039 ~ 0.051 in)
Valve stem runout
0.01 mm (0.0004 in)
EB403410
CHECKING THE VALVE SEATS
The following procedure applies to all of
the valves and valve seats.
1. Eliminate:
• carbon deposits
(from the valve face and valve seat)
2. Check:
• valve seat
Pitting/wear ® Replace the cylinder
head.
3. Measure:
• valve seat width a
Out of specification ® Replace the cyl-
inder head.
Valve seat width
0.9 ~ 1.1 mm
(0.035 ~ 0.043 in)
: 1.6 mm (0.06 in)

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ENGVALVES AND VALVE SPRINGS
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a. Apply Mechanic’s blueing dye
(Dykem) b onto the valve face.
b. Install the valve into the cylinder
head.
c. Press the valve through the valve
guide and onto the valve seat to make
a clear impression.
d. Measure the valve seat width.
NOTE:
Where the valve seat and valve face con-
tacted one another, the blueing will have
been removed.
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4. Lap:
• valve face
• valve seat
NOTE:
After replacing the cylinder head or
replacing the valve and valve guide, the
valve seat and valve face should be
lapped.
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a. Apply a coarse lapping compound a
to the valve face.
ACHTUNG:CAUTION:
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.
NOTE:
For the best lapping results, lightly tap
the valve seat while rotating the valve
back and forth between your hands.

4 - 28
ENGVALVES AND VALVE SPRINGS
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) b 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 impression.
j. Measure the valve seat width c
again. If the valve seat width is out of
specification, reface and lap the valve
seat.
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EB403420
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
Inner spring
Intake valve spring
32.35 mm (1.27 in)
: 30.73 mm
(1.21 in)
Exhaust valve spring
28.82 mm (1.13 in)
: 27.37 mm
(1.08 in)
Outer spring
Intake valve spring
36.42 mm (1.43 in)
: 34.60 mm
(1.36 in)
Exhaust valve spring
33.91 mm (1.34 in)
: 32.21 mm
(1.27 in)