Honda GP160H Manual page 93

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CYLINDER HEAD
VALVE SEAT WIDTH
Remove the carbon deposits from the combustion
chamber (page 3-8).
Inspect each valve face for irregularities.
If necessary, replace the valve.
Apply a light coat of Prussian Blue or erasable felt-
tipped marker ink to each valve seat.
Insert the valve, and snap it closed against its seat
several times. Be sure the valve does not rotate on the
seat.
The transferred marking compound will show any area
of the valve face that is not concentric.
Measure the valve seat width of the cylinder head.
STANDARD: 0.70 – 0.90 mm (0.028 – 0.035 in)
SERVICE LIMIT: 2.0 mm (0.08 in)
If the measurement is more than the service limit,
recondition the valve seat (page 12-9).
Check whether the valve seat contact area of the valve
is too high or too low.
If the valve seat is too high or too low, recondition the
valve seat (page 12-9).
VALVE GUIDE I.D.
Ream the valve guide to remove any carbon deposits
before measuring the guide [1] I.D.
TOOL:
Valve guide reamer 5.510 mm [2] 07984-2000001
• Turn the valve guide reamer (special tool) clockwise,
never counterclockwise.
• Continue to rotate the special tool while removing it
from the valve guide.
Measure and record each valve guide I.D.
STANDARD: 5.500 – 5.512 mm (0.2165 – 0.2170 in)
SERVICE LIMIT: 5.572 mm (0.2194 in)
If the measured valve guide I.D. is more than the
service limit, replace the cylinder head (page 12-4).
12-6
VALVE LAPPER
(Commercially available)
TOO LOW
VALVE SEAT
WIDTH
TOO HIGH
[2] HANDLE
(Commercially
available)
[1]