Valve Seat Inspection/Refacing; Valve Seat Refacing - Honda 1998 VT750C Service Manual

CYLINDER HEAD/VALVES
VALVE SEAT INSPECTION/REFACING
INSPECTION
Clean all intake and exhaust valves thoroughly to
remove carbon deposits.
Apply a light coating of Prussian Blue to each valve
face.
Tap the valve against the valve seat several times
using a hand-lapping tool, without rotating valve,
to make a clear pattern.
Remove the valve and inspect the valve seat face.
NOTE:
The valve cannot be ground. If the valve face is
burned or badly worn or if it contacts the seat
unevenly, replace the valve.
Inspect the valve seat face for:
o
Uneven seat width:
- Bent or collapsed valve stem;
Replace the valve and reface the valve seat.
Damaged face:
- Replace the valve and reface the valve seat.
o
Contact area (too high or too low area):
- Reface the valve seat.
Inspect the width of the valve seat.
The valve seat contact should be within the specified
width and even all around the circumference.
STANDARD: 0.90 -1.10 mm (0.035 - 0.043 in)
SERVICE LIMIT: 1.5 mm (0.06 in)
If the valve seat width is not within specification,
reface the valve seat.
VALVE SEAT REFACING
DAMAGED FACE
TOO LOW
UNEVEN SEAT
WIDTH
TOO HIGH
VALVE SEAT
CONTACT WI DTH
NOTE:
o
Follow the refacer manufacturer's operating
instruction.
o
Reface the valve seat whenever the valve guide
has been replaced.
o
Be careful not to grind the seat more than neces-
sary.
10-20
l