Honda GX270H Manual page 136

62Z7B000.book 5 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
INSPECTION
CYLINDER COMPRESSION CHECK
Start the engine and warm up to normal operating
temperature.
Turn the fuel valve lever to the OFF position, and then
remove the drain screw to drain the carburetor.
Remove the spark plug cap [1] from the spark plug.
Remove the spark plug using a spark plug wrench.
Pull the recoil starter several times to expel unburned
gas.
Attach a commercially available compression gauge [2]
to the spark plug hole.
Pull the recoil starter forcefully to measure stable
cylinder compression.
CYLINDER COMPRESSION:
1.37 MPa (14.0 kgf/cm
CYLINDER HEAD WARPAGE
Remove the carbon deposits from the combustion
chamber (page 3-15).
Check the spark plug hole and valve areas for cracks.
Check the cylinder head warpage using a straightedge
[1] and feeler gauge [2].
SERVICE LIMIT:
If the measurement is more than the service limit,
replace the cylinder head (page 13-4).
VALVE SEAT WIDTH
Remove the carbon deposits from the combustion
chamber (page 3-15).
Inspect each valve for face irregularities.
If necessary, replace the valve (page 13-4).
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:
SERVICE LIMIT:
If the measurement is more than the service limit,
recondition the valve seat (page 13-10).
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 (page 13-10).
2 , 199 psi) / 1400 min -1 (rpm)
0.10 mm (0.004 in)
1.0 – 1.2 mm (0.04 – 0.05 in)
2.0 mm (0.08 in)
CYLINDER HEAD/VALVES
[1]
[2]
VALVE LAPPER
(Commercially
available)
CONTACT TOO HIGH
VALVE SEAT
WIDTH
[2]
[1]
13-5