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1.Measure the free height of
the spring and, if is smaller than the limit,
replace.
Standard value: 48.8
mm
Limit: 47.8 mm
2.Measure
the squareness of the spring and, if the limit is exceeded,
replace.
Standard value: Less
than 2°
Limit: 4°
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Checking Stem for
Wear
If the diameter is below the specified
service limit or uneven wear is recognized, replace
the valve.
| note |
If the valve is new, be
sure to lap it and the valve seat for proper
seating.
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Standard
value:
Intake: 7.96 -
7.97 mm
Exhaust: 7.93 -
7.95 mm
Limite:
Intake:
7.85 mm
Exhaust: 7.85 mm
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Valve Seat Angle and Valve
Margin
If the specified service limit is
exceeded by correcting the seat angle, replace the
valve.
Standard
value: 45°
±
15’
Standard
value: 1 mm
Limit: 0.8 mm
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1.If the clearance exceeds
the specified service limit, replace the defective
part.
Standard
value:
Intake: 0.03 -
0.05 mm
Exhaust: 0.05 -
0.08 mm
Limite:
Intake:
0.10 mm
Exhaust: 0.15 mm
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|
1.Apply an even coat of
minium to the valve seating surface of the valve
seat.
2.Strike the valve against the valve seat
once while taking care that the valve is not
rotated.
| note |
Before proceeding with the
contact check, examine the valve and valve guide
in detail
to see if they are in normal condition.
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3.Determine the valve
seating condition from minium pattem printed on the valve.
If any
abnormal contact is found take the following corrective
action.
|
Corrective action.
|
Minor
defect
|
Lap
valve for better seating.
|
Major
defect
|
Correct
or replace valve and valve seat.
|
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|
Valve seat width
If
the specified service limit is exceeded, replace the
valve seat.
Standard
value: 2 mm
Limit: 2.8 mm
| note |
When the valve seat has been
corrected or replaced lap it and the valve for
proper seating.
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Valve Sinkage from Cylinder Head
Bottom
If the specified service limit is
exceeded, correct or replace the defective
part.
Standard
value:
Intake: 0.75 -
1.25 mm
Exhaust: 0.95 -
1.45 mm
Limite:
Intake:
1.5 mm
Exhaust: 1.7 mm
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|
1.Measure the distortion of
the bottom surface of the cylinder head. If the measured
value
exceeds the limit, replace the cylinder
head.
Standard value: Less than
0.05 mm
Limit: 0.2 mm
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INLET VALVE AND EXHAUST
VALVE
| caution |
- The grinding should be
minimum.
- If the valve margin deviates from
the specified service limit after
grinding, replace
the valve.
- After grinding, lap the valve and
valve seat for proper
seating.
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|
|
Lap the valve and
valve seat as follows:
- Apply a thin coat of lapping compound
evenly to the valve
seating surface of the valve seat.
-
| caution |
- Keep the stem of the valve
free from the
lapping compound.
- Use an intermediate- mesh
compound (120 -
150 meshes) first, then a
fine
- mesh compound (over 200
meshes).
- To achieve even application
of the lapping compound, a
mix with a small quantity
of engine oil is
recommended.
|
- Using Valve Lapper, strike the valve
against the valve seat a few times while turning
little by little.
- Wash off the lapping compound in
kerosene.
- Apply a thin coat of engine oil to the
seating surface of the valve seat and oil
lap.
- Check the seat contact between the
valve and valve seat.
- Replace the valve seat if
necessary.
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|
1.Grind the valve seat using
a valve seat cutter or a valve seat
grinder.
2.Polish the ground surface lightly using
a #400 sandpape held between the
cutter and valve seat.
3.Correct the seat width of
the valve to the specified value using a 15°
or
75°
cutter.
| caution |
Be sure that the sinkage
E of the valve does not exceed the specified
service limit as a result of the
correction.
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4.After the correction, lap the valve and valve
seat for proper seating.
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