Honda NC700 2012, Service Manual

Page: 329 / 773

10-22
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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.
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.
[1]
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)
SEAT WIDTH