Valve Seat Inspection/Refacing - Honda SH125 Manual

CYLINDER HEADNALVES
The valve cannot
be Remove the valve and inspect the valve seat face.
ground. / f the valve
The valve seat contact should be within the speci-
face
Is
burned or
fied width and even all around the circumference.
-
~~
~~
Remove the guides from the freezer.
While the cylinder head is still heated, drive new
valve guides into the cylinder head from the cam-
shaft side until the exposed height is at the specified
value (at the mark).
TOOL:
Valve guide driver, 5.0 mm
VALVE GUIDE PROJECTION:
07942-MA60000
IN/EX: 11.35
-
11.65 mm (0.447
-
0.459 in)
Let the cylinder head cool to room temperature.
I
Use cutting oil on
Ream the new valve guides.
the reamer during
Insert the reamer from the combustion chamber
this operation. Take
side of the cylinder head and always rotate the
care not to tilt or
reamer clockwise.
TOOL:
Valve guide reamer, 5.0 mm 07984-MA60001
learn the reamer in
the guide while
Clean the cylinder head thoroughly to remove any
metal particles after reaming and reface the valve
seats (page 8-17).
VALVE SEAT INSPECTION/REFACING
Clean the intake and exhaust valves thoroughly to
remove carbon deposits.
Apply
a
light coat of Prussian Blue to each valve
seat.
Tap the valve against the valve seat several times
without rotating the valve, to check for proper valve
seat contact.
badly worn or rf it
STANDARD: 0.90
-
1.10 mm (0.035
-
0.043 in)
contacts the seat
unevenly, replace
SERVICE LIMIT: 1.8 mm (0.07 in)
the valve.
If the seat width
is
not within specification, reface
the valve seat.
. c
f
SEAT WIDTH