l
Valve seat repair:
Valve seat not producing uniform contact
with its valve or showing width @ of seating
contact that is off the specified range must be
repaired by regrinding or by cutting and
regrinding and finished by lapping.
1) EXHAUST VALVE SEAT: Use a valve seat
cutter to make three cuts as illustrated in Fig.
3-5-16. Three cutters must be used: the first
for making 15” angle, the second for making
75” angle and the last for making 45”
Seat
angle. The third cut must be made to produce
desired seat width
@I!).
Seat width
@
for
1.3-
1.5 mm
exhaust valve seat
(0.0512
-
0.0590 in.)
1.
Valve
seat
CUtter
Fig.
3-S
15 Valve seat cutting
Fig.
3-5-
16
Valve seat angles for exhaust valve
2)
INLET VALVE SEAT: Cutting sequence is
the same as for exhaust valve seats but the
second angle is
(60”
).
Seat width
@I
for
1.3-
1.5mm
inlet valve seat
I
(0.0512
-
0.0590 in.)
Fig.
3-5-
17
Valve seat angles for in take valve
3) VALVE LAPPING. Lap valve on seat in two
steps, first with coarse-size lapping com-
pound applied to its face and the second with
a fine-size compound, each time using a valve
lapper according to usual lapping method.
Fig.
3-5-
18 Applying lapping compound to
valve face
NOTE:
l After lapping, wipe compound off valve face
and seat, and produce contact pattern with
marking compound. Check to be sure that
contact is centered
widthwise
on valve seat
and that there is no break in contact pattern
ring.
a
Be sure to check and, as necessary, adjust
valve clearance after reinstalling cylinder
head and valve mechanism.
3-22
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