Honda GX270H Manual page 141

62Z7B000.book 10 ページ ２０１２年９月２７日 木曜日 午前１０時２１分
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CYLINDER HEAD/VALVES
Check the valve guide bore; it should be straight, round
and centered in the valve guide. Insert the valve and
check operation. If the valve does not operate
smoothly, the guide may have been bent during
installation.
Replace the valve guide if it is bent or damaged.
Check the valve guide-to-stem clearance.
VALVE SEAT RECONDITIONING
Thoroughly clean the combustion chamber and valve
seats to remove carbon deposits (page 3-15).
Apply a light coat of Prussian Blue or erasable felt-
tipped marker ink to the 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 seat that is not concentric.
Measure the valve seat width of the cylinder head.
STANDARD:
SERVICE LIMIT:
If the measurement is more than the service limit,
recondition the valve seat.
Check whether the valve seat contact area of the valve
is too high.
If the valve seat is too high or too low, recondition the
valve seat.
Valve seat cutters [1]/grinder or equivalent valve seat
refacing equipment is recommended to correct a worn
valve seat.
Turn the cutter clockwise, never counterclockwise.
Continue to turn the cutter as you lift it from the valve
seat.
13-10
1.0 – 1.2 mm (0.04 – 0.05 in)
2.0 mm (0.08 in)
VALVE LAPPER
(Commercially
available)
[1]