Yamaha Fz6n Manual

							5-21
CYLINDER HEADENG
NOTE:
19 Nm (1.9 m
kg, 14 ft
lb)
50 Nm (5.0 m
kg, 36 ft
lb)
12 Nm (1.2 m
kg, 8.7 ft
lb)
NOTE:
EAS00233
INSTALLING THE CYLINDER HEAD
1. Install:

gasket 
New 1

dowel pins 2
2. Install:

cylinder head
Pass the timing chain through the timing chain 
cavity.
3. Tighten:

cylinder head bolts 
1 
 10
1st
2nd

cylinder head bolts 
11, 12

Lubricate the cylinder head bolts with engine
oil.

Tighten the cylinder head bolts in the proper
tightening sequence as shown and torque
them in two stages.

First, tighten the bolts 
1 
 10 to approximate-
ly 19 Nm (1.9 m
kg, 14 ft
lb) with a torque
wrench and then tighten the 50 Nm (5.0 m
kg,
36 ft
lb).
4. Install:

exhaust camshaft

intake camshaft
Refer to “INSTALLING THE CAMSHAFTS”. 
						

							5-22
Order Job / Part Q’ty Remarks
1
2
3
4
5
6
7
8
9
10
11
12
13Remove the valves and valve springs
Cylinder head
Intake valve lifter
Intake valve pad
Intake valve cotter
Intake valve upper spring seat
Intake valve spring outer
Intake valve spring inner
Intake valve stem seal
Intake valve lower spring seat
Intake valve
Intake valve guide
Exhaust valve lifter
Exhaust valve pad
Exhaust valve cotter8
8
16
8
8
8
8
8
8
8
8
8
16Remove the parts in the order listed.
Refer to “CYLINDER HEAD”.
Refer to “REMOVING / INSTALLING
THE VALVES”.
VALVES AND VALVE SPRINGSENG
EAS00236
VALVES AND VALVE SPRINGS 
						

							5-23
VALVES AND VALVE SPRINGSENG
Order Job / Part Q’ty Remarks
14
15
16
17
18
19Exhaust valve upper spring seat
Exhaust valve spring
Exhaust valve stem seal
Exhaust valve lower spring seat
Exhaust valve
Exhaust valve guide8
8
8
8
8
8
For installation, reverse the removal 
procedure.
Refer to “REMOVING / INSTALLING
THE VALVES”. 
						

							5-24
VALVES AND VALVE SPRINGSENG
NOTE:
NOTE:
NOTE:
NOTE:
EAS00238
REMOVING THE VALVES
The following procedure applies to all of the
valves and related components.
Before removing the internal parts of the cylin-
der head (e.g., valves, valve springs, valve
seats), make sure the valves properly seal.
1. Remove:

valve lifter 
1

valve pad 2
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 sealing
Leakage at the valve seat 
 Check the valve
face, valve seat, and valve seat width.
Refer to “CHECKING THE VALVE SEATS”.
a. Pour a clean solvent 
a into the intake and
exhaust ports.
b. Check that the valves properly seal.
There should be no leakage at the valve seat 
1.
3. Remove:

valve cotters 
1
Remove the valve cotters by compressing the
valve springs with the valve spring compressor
2 and the valve spring compressor attachment
3. 
						

							5-25
VALVES AND VALVE SPRINGSENG
NOTE:
Valve spring compressor
90890-04019, YM-04019
Valve spring compressor 
attachment
90890-04108, YM-01253
4. Remove:

upper spring seat 
1

valve spring outer 2

valve spring inner (intake only) 3

valve 4

valve stem seal 5

lower spring seat 6
Identify the position of each part very carefully
so that it can be reinstalled in its original place.
EAS00239
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
Valve-stem-to-valve-guide clearance =
Valve guide inside diameter 
a –
Valve stem diameter 
b
Out of specification 
 Replace the valve
guide.
Valve-stem-to-valve-guide 
clearance
Intake
0.010 
 0.037 mm 
(0.0004 
 0.0015 in)
: 0.08 mm (0.0031 in)
Exhaust
0.025 
 0.052 mm 
(0.0010 
 0.0020 in)
: 0.10 mm 
(0.0039 in) 
						

							5-26
VALVES AND VALVE SPRINGSENG
NOTE:
NOTE:
2. Replace:

valve guide
To ease valve guide removal and installation,
and to maintain the correct fit, heat the cylinder
head to 100C (212F) in an oven.
a. Remove the valve guide with the 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 the valve guide reamer 
3 to
obtain the proper valve-stem-to-valve-guide
clearance.
After replacing the valve guide, reface the valve
seat.
Valve guide remover 
(4 mm, 0.16 in)
90890-04111,
Valve guide installer 
(4 mm, 0.16 in)
90890-04112,
Valve guide reamer (4 mm, 0.16 in)
90890-04113, YM-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. 
						

							5-27
VALVES AND VALVE SPRINGSENG
NOTE:
5. Measure:

valve margin thickness 
a
Out of specification 
 Replace the valve.
Valve margin thickness
0.6 
 0.8 mm 
(0.0236 
 0.0315 in)
: 0.5 mm (0.02 in)
6. Measure:

valve stem runout
Out of specification 
 Replace the valve.

When installing a new valve, always replace
the valve guide.

If the valve is removed or replaced, always re-
place the oil seal.
Valve stem runout
: 0.04 mm (0.0016 in)
EAS00240
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 cylinder
head.
Valve seat width
0.9 
 1.1 mm 
(0.0354 
 0.0433 in)
: 1.6 mm (0.06 in)
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 impres-
sion.
d. Measure the valve seat width. 
						

							5-28
VALVES AND VALVE SPRINGSENG
NOTE:
NOTE:
CAUTION:
NOTE: Where the valve seat and valve face contacted
one another, the blueing will have been re-
moved.
4. Lap:

valve face

valve seat
After replacing the cylinder head or replacing
the valve and valve guide, the valve seat and
valve face should be lapped.
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) 
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 impres-
sion. 
						

							5-29
VALVES AND VALVE SPRINGSENG
j. Measure the valve seat width c 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 (inner)
37.0 mm (1.46 in)
: 35.2 mm (1.39 in)
Intake valve spring (outer)
38.4 mm (1.51 in)
: 36.5 mm (1.44 in)
Exhaust valve spring
41.8 mm (1.65 in)
: 39.7 mm (1.56 in)
2. Measure:

compressed valve spring force 
a
Out of specification 
 Replace the valve
spring.
bInstalled length
Compressed valve spring force 
(installed)
Intake valve spring (inner)
69.0 
 79.0 N
(7.03 
 8.05 kg,
15.50 
 17.75 lb)
Intake valve spring (outer)
114.0 
 132.0 N
(11.62 
 13.46 kg, 
25.63 
 29.67 lb)
Exhaust valve spring
160 
 184 N 
(16.32 
 18.76 kg,
35.97 
 41.36 lb) 
						

							5-30
VALVES AND VALVE SPRINGSENG
3. Measure:

valve spring tilt 
a
Out of specification 
 Replace the valve
spring.
Spring tilt limit
Intake valve spring (inner)
2.5/ 1.6 mm (0.06 in)
(outer)
2.5/ 1.7 mm (0.07 in)
Exhaust valve spring
2.5/ 1.8 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.
EAS00246
INSTALLING THE VALVES
The following procedure applies to all of the
valves and related components.
1. Deburr:

valve stem end
(with an oil stone)
2. Lubricate:

valve stem 
1

valve stem seal 2
(with the recommended lubricant)
Recommended lubricant
Molybdenum disulfide oil
3. Install:

valve 
1

lower spring seat 2

valve stem seal 3

valve spring inner (intake only) 4

valve spring outer 5

upper spring seat 6
(into the cylinder head)