Honda NC700 2012 Service Manual page 329

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CYLINDER HEAD/VALVES
VALVE SEAT INSPECTION/REFACING
Clean the intake and exhaust valves thoroughly to
remove carbon deposits.
Apply a light coating of Prussian Blue to the valve
seats.
Tap the valves and seats using a rubber hose or other
hand-lapping tool [1].
Remove the valve and inspect the valve seat face.
The valve seat contact should be within the specified
width and even all around the circumference.
STANDARD:
IN: 0.90 – 1.10 mm (0.035 – 0.043 in)
EX: 1.30 – 1.50 mm (0.051 – 0.059 in)
SERVICE LIMITS:
IN: 1.5 mm (0.06 in)
EX: 1.9 mm (0.07 in)
If the seat width is not within specification, reface the
valve seat (page 10-23).
Inspect the valve seat face for:
• Uneven seat width:
– Replace the valve and reface the valve seat.
• Damaged face:
– Replace the valve and reface the valve seat.
The valves cannot be ground.
If a valve face is burned or badly worn or if it contacts
the seat unevenly, replace the valve.
• Contact area (too high or too low)
– Reface the valve seat.
10-22
[1]
SEAT WIDTH