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1.Before cleaning the
cylinder head, check it for traces of water and gas leakage
and for cracks and any other damage.
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2.Thoroughly remove oils,
scale, sealants, carbon and other contamination. Clean the
oil passages, then check using compressed air that they are
not blocked.
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| caution |
The thickness of the metal
that can be removed by grinding from both the
cylinder head and the mating cylinder block is
limited to 0.2 mm in total.
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3.Check the cylinder head gasket surface for
warp using a straightedge and thickness gauge. If the
surface is warped beyond the limit, grind the surface for
rectification.
Gasket surface
warp
Standard value: Less than 0.03
mm
Limit: 0.2 mm
Grinding limit: 0.2
mm
Cylinder head height
(standard value
for new part):
119.9 - 120.1 mm
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1.Check the valve face for
correct contact with the seat. Reface the valve if the
contact is partial or one sided.
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2.Replace the valve if its
margin is smaller than the limit.
Standard
values:
Inlet 1.0 mm
Exhaust 1.2
mm
Limits:
Inlet 0.5
mm
Exhaust 0.7 mm
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3.Measure the total length
of the valve. Replace the valve if the length is less than
the limit.
Standard values:
Inlet
112.30 mm
Exhaust 114.11
mm
Limits:
Inlet 111.80
mm
Exhaust 113.61 mm
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1.Measure the free height of
the spring. Replace the spring if its height is smaller than
the limit.
Standard value: 50.8 mm
Limit:
49.8 mm
2.Measure the squareness of the
spring. Replace the spring if it is out of square beyond the
limit.
Standard value: 2° or
smaller
Limit: 4°
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Measure the valve guide inside
diameter and valve stem diameter to calculate the clearance
between the valve guide and valve stem. If the limit is
exceeded, replace the valve guide or valve, or
both.
Standard values:
Inlet 0.02
- 0.05 mm
Exhaust 0.04 - 0.07
mm
Limits:
Inlet 0.10
mm
Exhaust 0.15 mm
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Assemble the valve, then measure
the contact width. If the measurement exceeds the specified
limit, replace the valve seat.
Standard value:
0.9 - 1.3 mm
| caution |
If the variation in the width
exceeds 0.2 mm even if the contact width is
within the standard value, replace or correct
the valve sheet.
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1.Before reconditioning the
valve seat, check the clearance between the valve guide and
valve stem and, if necessary, replace the valve
guide.
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2.Resurface the valve seat
to the indicated width and angles.
3.After
resurfacing, lap the valve and valve seat using lapping
compound. Then, check the valve stem projection (refer to
VALVE SEATS in the INSPECTION section).
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1.Cut inside of the valve
seat to be replaced until its wall becomes thin enough for
removal, then remove the valve seat.
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2.Rebore the valve seat hole
in the cylinder head to a diameter matched to the diameter
of the selected oversize valve seat.
Inlet
valve seat hole diameter:
0.3 oversize:
34.300 - 34.325 mm
Exhaust valve
seat hole diameter:
0.3 oversize: 31.800
- 31.825 mm
3.Before
fitting the valve seat, cool it in liquid nitrogen to
prevent damage to its hole in the cylinder head due to
interference.
4.Resurface the valve seat. Refer
to , the VALVE
SEAT RECONDITIONING section.
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1.Force out the valve guide
toward the cylinder block using a press.
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2.Machine the valve guide
hole in the cylinder head to the size matched to the
selected oversize valve guide.
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Valve guide hole
diameters
0.05 oversize: 11.050 -
11.068 mm
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3.Press-fit the valve guide
until it remains protruded above the cylinder head by the
amount indicated in the drawing.
Protrusion:
13.7 - 14.3 mm
| note |
Press the valve guide from
above the cylinder head.
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| note |
The valve guides for the inlet
valves are different in length from those for
the exhaust valves (45.5 mm for inlet valves;
50.5 mm for exhaust valves)
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4.After installing the valve guide, insert a
new valve in it to check for smooth movement.
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