Yamaha Fz1n Service Manual

							
VALVES AND VALVE SPRINGS
5-23
16 Exhaust valve lower spring seat 8
17 Exhaust valve 8
18 Exhaust valve guide 8For installation, reverse the removal 
procedure.
Removing the valves and valve springs
Order Job/Parts to remove Q’ty Remarks 
						

							
VALVES AND VALVE SPRINGS
5-24
EAS24280
REMOVING THE VALVES
The following procedure applies to all of the 
valves and related components.
NOTE:
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”
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 sealingLeakage at the valve seat  → Check the 
valve face, valve seat, and valve seat width.
Refer to CHECKING THE VALVE SEATS 
on page 5-26.
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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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3. Remove:  Valve cotters “1”
NOTE:
Remove the valve cotters by compressing the 
valve spring with the valve spring compressor 
“2” and the valve spring compressor attach-
ment “3”.
4. Remove: Upper spring seat “1”
 Valve spring “2”
 Valve stem seal “3”
 Lower spring seat “4”
Valve “5”
NOTE:
Identify the position of each part very carefully 
so that it can be reinstalled in its original place.
Valve spring compressor
90890-04019
YM-04019
Valve spring compressor 
attachment
90890-04108
Valve spring compressor 
adapter 22 mm
YM-04108
Valve spring compressor 
attachment 90890-04114
Valve spring compressor 
adapter 19.5 mm YM-04114 
						

							
VALVES AND VALVE SPRINGS
5-25
EAS24290
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.
2. Replace: Valve guideNOTE:
To ease valve guide removal and installation, 
and to maintain the corre ct fit, heat the cylinder 
head to 100°C (212 °F) in an oven.
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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.
NOTE:
After replacing the valve guide, reface the 
valve seat.
 Valve-stem-to-valve-guide clearance =
Valve guide inside diameter “a” -
Valve stem diameter “b”
Valve-stem-to-valve-guide clear-
anceIntake
0.010 – 0.037 mm
(0.0004 – 0.0015)
Limit
0.08 mm (0.0032 in)
Exhaust 0.025 – 0.052 mm
(0.0010 – 0.0020 in)
Limit 0.10 mm (0.0039 in) 
						

							
VALVES AND VALVE SPRINGS
5-26
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3. Eliminate: Carbon deposits(from the valve face and valve seat)
4. Check:
Valve facePitting/wear  → Grind the valve face.
 Valve stem end
Mushroom shape or diameter larger than 
the body of the valve stem  → Replace the 
valve.
5. Measure:  Valve margin thickness “a”Out of specification  → Replace the valve. 6. Measure:
 Valve stem runoutOut 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.
EAS24300
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.
Intake Valve guide remover (ø4)90890-04111
YM-04111
Exhaust Valve guide remover (ø4.5)
90890-04116
YM-04116
Intake
Valve guide installer (ø4)90890-04112
YM-04112
Exhaust Valve guide installer (ø4.5)90890-04117
YM-04117
Intake Valve guide reamer (ø4)
90890-04113
YM-04113
Exhaust
Valve guide reamer (ø4.5)90890-04118
YM-04118
Valve margin thickness0.5–0.9 mm (0.0197–0.0354 in)
Limit 0.5 mm (0.02 in)
Valve stem runout
0.01 mm (0.0004 in) 
						

							
VALVES AND VALVE SPRINGS
5-27
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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 contacted 
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.
CAUTION:
ECA13790
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.
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.
Valve seat widthIntake0.90–1.10 mm
(0.0354–0.0433 in)
Exhaust 0.90–1.10 mm
(0.0354–0.0433 in)
Limit 1.6 mm (0.063 in) 
						

							
VALVES AND VALVE SPRINGS
5-28
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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EAS24310
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. 2. Measure:
 Compressed valve spring force “a”Out of specification  → Replace the valve 
spring.
3. Measure:  Valve spring tilt “a”Out of specification  → Replace the valve 
spring.
Valve spring free length Intake valve spring
40.5 mm (1.60 in)
Limit 38.5 mm (1.47 in)
Exhaust valve spring 40.5 mm (1.60 in)
Limit
38.5 mm (1.47 in)
Compressed valve spring force 
(installed)
Intake valve spring127.4–144.6 N
(12.99–14.74 kg, 28.64–32.51 
lb)
at 32.65 mm (1.285 in)
Exhaust valve spring 133.0–153.0 N
(13.56–15.60 kg, 29.90–34.39 
lb)
at 32.82 mm (1.292 in)
b. Installed length
Spring tilt limitIntake valve spring 1.8 mm (0.07 in)
Exhaust valve spring 1.8 mm (0.07 in) 
						

							
VALVES AND VALVE SPRINGS
5-29
EAS24320
CHECKING THE VALVE LIFTERS
The following procedure applies to all of the 
valve lifters.
1. Check: Valve lifterDamage/scratches  → Replace the valve 
lifters and cylinder head.
EAS24330
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) 3. Install:
Valve “1”
 Lower spring seat “2”
 Valve stem seal “3”
 Valve spring “4”
 Upper spring seat “5”(into the cylinder head)
NOTE:
 Make sure each valve is installed in its origi-
nal place. Refer to the following embossed 
marks.
Right and left intake valve (-s): “5VY:”
Middle intake valve (-s): “5VY.”
Exhaust valve (-s): “5VY”.
 Install the valve springs with the larger pitch 
“a” facing up.
4. Install:  Valve cotters “1”
NOTE:
Install the valve cotters by compressing the 
valve springs with the valve spring compressor 
“2” and the valve spring compressor attach-
ment “3”.
Recommended lubricantMolybdenum disulfide oil
b. Smaller pitch 
						

							
VALVES AND VALVE SPRINGS
5-30
5. To secure the valve cotters onto the valve stem, lightly tap the valve tip with a soft-
face hammer.
CAUTION:
ECA13800
Hitting the valve tip with excessive force 
could damage the valve.
6. Install:
 Valve pad “1”
 Valve lifter “2”
NOTE:
 Lubricate the valve lifter and valve pad with molybdenum disulfide oil.
 The valve lifter must move smoothly when  rotated with a finger.  Each valve lifter and valve pad must be rein-
stalled in its original position.Valve spring compressor
90890-04019
YM-04019
Intake Valve spring compressor 
attachment
90890-04114
YM-04114
Exhaust
Valve spring compressor 
attachment
90890-04108
YM-04108 
						

							
GENERATOR
5-31
EAS24480
GENERATOR
Removing the generator
Order Job/Parts to remove Q’ty RemarksRider and passenger seat Refer to GENERAL CHASSIS on  page 4-1.
Fuel tank Refer to FUEL TANK on page 7-1.
Engine oil Drain. Refer to CHANGING THE ENGINE 
OIL on page 3-12.
1 Stator coil assembly  lead coupler 1 Disconnect.
2Plug 1
3 Generator rotor cover 1
4Gasket 1
5 Dowel pin 2
6 Generator rotor assembly 1
7 Stator coil assembly 1
8 Dowel pin 2
9 Bearing housing 1
10 Collar 1 
						

							
GENERATOR
5-32
11 Bearing 1
12 Stator coil assembly lead holder 1
13 Idler gear 1
14 Idler gear shaft 1
15 Washer 1
16 Bearing 1For assembly, reverse the removal 
procedure.
Removing the generator
Order Job/Parts to remove Q’ty Remarks