Honda GX630, Workshop Manual

Page: 116 / 149

CYLINDER
14-6
PISTON DISASSEMBLY/ASSEMBLY
Remove the piston (page 14-2).
CYLINDER/PISTON INSPECTION
CYLINDER COMPRESSION CHECK
Start the engine and warm up to normal operating
temperature.
Turn the fuel valve lever of the application to the OFF
position, and then loosen the carburetor drain screw to
drain the float chamber.
Remove the spark plug cap from the spark plug.
Remove the spark plug using a spark plug wrench.
Operate the starter motor to expel unburned gas.
Attach a compression gauge (1) to the spark plug hole.
Operate the starter motor to measure stable cylinder
compression.
Do not operate the starter motor for more than 5
seconds at a time. When operating the starter motor
several times in a row, wait 10 – 20 seconds between
operation to recover the battery voltage.
ASSEMBLY:
The top ring (1) and second ring (2) are not
interchangeable.
Install the top ring and second ring on the piston
with the mark side facing up.
Check that the piston rings rotate smoothly after
installing them.
Space the piston ring end gaps 120 degrees
apart, and do not align the ring end gaps with the
piston pin bore.
PISTON RING SET
MARK
TOP RING
SECOND RING
SIDE RAIL
SPACER
OIL RING
(COMBINATION
RING)
(1)
(2)
10 mm (0.4 in)
120°
120°
120°
10 mm (0.4 in)
CYLINDER COMPRESSION:
0.5 – 0.7 MPa (5.09 – 7.14 kgf/cm
2
, 73 – 102 psi) / 500
min
-1
(rpm)
(1)
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