SERVICING
Valve Recessing
1.
Clean the cylinder head, the valve face and
seat
2. Insert the valve into the valve guide.
3.
Measure the valve recessing with a depth gauge.
4.
If the measurement exceeds the allowable limit, replace the
valve.
If
it still exceeds the allowable limit after replacing the valve,
replace the
cylinder head.
(Protrusion)
Factory Intake o mm (0 in.)
to
spec. valve (recessing)
0.2
mm
(0.0079 in.)
Valve recessing
(Protrusion)
Factory Exhaust
0.'5
mm
(0.0059 in.)
to
spec. valve
(recessing)
,
0.05
mm
(0.00t9
in.)
Allowable (recessing)
limit
0.4 mm (0.0157 in.)
Valve Lapping
1.
Apply compound evenly to the valve lapping surface.
2.
Insert the valve into the valve guide. Lap the valve onto its
seat with a
valve flapper or screwdriver.
3.
After lapping the valve, wash the compound away and apply
oil, then repeat valve lapping with oil.
4. Apply prussian blue to the contact surface to check the seated
rate.
If it is 'Iess than
70
%, repeat valve lapping again.
•
IMPORTANT
• When valve lapping is performed, be sure to check the
valve recessing and adjust the valve clearance after
assembling the valve.
Clearance between Valve Stem and Valve Guide
1.
Remove carbon from
the
valve guide section.
2.
Measure the valve stem
0.0.
with an outside micrometer.
3.
Measure the valve guide 1.0. of the cylinder head
at
the most
wear part
as
shown
with
a small hole
gauge.
And
calculate the clearance.
4.
If the clearance exceeds the allowable limit, replace the
valves.
If it still exceeds the allowable limit, replace the valve
guide.
Intake
6.960
to
6.975
mm
Factory
valve
0.2740
to
0.2746 in.
Valve stem
0.0.
spec.
Exhaust
7.960
to
7.975 mm
valve
0.3134
to 0.3140 in.
DEPTH
GAUGE
,*-.l-U))
CYLINDER
HEAD
SURFACE
CYLINDER
HEAD
SURFACE
~~~(A~)~~~~\~i
(8)
0
+
CORRECT
D.D.
Factory
(A) Recessing
(8)
Protrusion
..
(
.....
,
~.J
0
INCORRECT
INCORRECT
Intake
0.055
to
0.085 mm
valve
0.0022
to
0.0033 in.
Intake
7.030
to
7.045 mm
Clearance between
spec.
Exhaust
0.040
to
0.070 mm
Factory
valve
0.2768
to
0.2774 in.
Valve guide
1.0.
spec.
Exhaust
8.015
to 8.030 mm
valve
0.3155 to 0.3161 in.
valve stem
and
guide
valve
0.0016
to
0.0028 in.
Allowable limit
0.1
mm
0.0039 in.
Engines & Generators
41
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