Compression Pressure And Oil Perssure - HYOSUNG GF125 Service Manual

3-1 SERVICING ENGINE
COMPRESSION PRESSURE AND OIL PRESSURE
COMPRESSION PRESSURE
NOTE:
● Before inspecting for compression pressure,
make sure that the cylinder head nuts and
bolts are tightend to specified torque values
and valves are properly adjusted.
● Have the engine warmed up by idling before
testing it.
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②
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● Remove spark plug.
● Fit the compression gauge ① and adapter ② to the
plug hole, taking care to make the connection abso-
lutely tight.
● Twist the throttle grip into wide-open position.
● Crank the engine several times with the starter motor or
kick starter, and read the highest gauge indication as
the compression of the cylinder.
Compression pressure
Standard
2
12-15 kg/cm
A low compression pressure may indicate any of the fol-
lowing malfunction:
● Excessively worn cylinder wall.
● Worn piston or piston rings.
● Piston rings stuck in the grooves.
● Poor seating contact of valves.
● Defective cylinder head gasket
When the compression pressure noted is down to or
below the limit indicated above, the engine must be dis-
assembled, inspected and repaired as required to over-
haul the engine, with these five malconditions in mind.
①
Compression gauge
Adapter
Limit
2
8 kg/cm
②
OIL PRESSURE
Install the oil pressure gauge in the position shown in the
illustration.
Warm up the engine as follows:
● Summer approx, 10min. at 2000r/min.
● Winter approx. 20min. at 2000r/min.
After the warming up operation, increase the engine speed
to 3,000r/min, and read the oil pressure gauge.
NOTE:
● Engine oil must be warmed up to 60℃(140。 F)when checking the
oil pressure.
Oil pressure
2
Above 0.4 kg/cm (Oil temp. at 60℃)
Below 0.6 kg/cm 2 at 3,000rpm
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If the oil pressure is power or higher than the specifica-
tions, several causes may be considered
● Low oil pressure is usually the result of a clogged oil
filter, oil leakage from the oil passageway,damaged oil
seal, a defective oil pump or a combination of these
items.
● High oil pressure is usually caused by a engine oil
which is too heavy a weight, a clogged oil passage,
improper installation of the oil filter or a combination
of these items.
Oil pressure gauge