INSPECTION AND REPAIR OF BASIC ENGINE
6-5
1.7 Inspecting valve face
Apply a thin coat of Shinmyoutan or equivalent lead-free
coloring paste on the valve face, and strike the valve face
against the valve seat using a valve lapper to check for
contact condition. If the contact is not even, or any defects
are found, or if the limit is exceeded, reface or replace the
valve.
Note: (a) Inspect the valve face after the valve guide is
repaired or replaced.
(b) Do not rotate the valve when pressing the valve
face coated with Shinmyoutan or equivalent lead-
free dye against the valve seat.
(c) Always lap the valve and valve seat after the
valve has been refaced or replaced.
Checking valve face
Valve-to-valve seat contact
Valve-to-valve seat contact position
Item Nominal Standard Limit
Valv e
seat
Valv e
seat angle
30° - -
Valv e
sinkage
0.8 mm
[0.031 in.]
0.7 to 0.9 mm
[0.028 to 0.035 in.]
1.3 mm
[0.051 in.]
Seat
width
1.18 mm
[0.0465 in.]
1.04 to 1.32 mm
[0.0409 to 0.0520 in.]
1.6 mm
[0.063 in.]
Valve margin
1.7 mm
[0.067 in.]
-
Refacing per-
missible up to
1.2 mm
[0.047 in.]
Valve lapper
Shinmyoutan
Good Bad
Valve margin
Valve sinkage
Valve seat
angle
Seat width
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