Yamaha YFM660RN, Service Manual, Page: 75 / 328

3 - 19
CHK
ADJ
MEASURING THE COMPRESSION PRESSURE/
CHECKING THE ENGINE OIL LEVEL
***********************************************
Measurement steps:
●
Crank over the engine with the electric
starter (be sure the battery is fully charged)
with the throttle fully-open until the compres-
sion reading on the gauge stabilizes.
WARNING
When cranking the engine, ground the
spark plug lead to prevent sparking.
***********************************************
7.Install:
●
Spark plug
Compression pressure (at sea level):
Standard:
1,250 kPa (12.5 kg/cm
2
, 181 psi)
Minimum:
1,050 kPa (10.5 kg/cm
2
, 149 psi)
Maximum:
1,350 kPa (13.5 kg/cm
2
, 192 psi)
T
R .
.
18 Nm (1.8 m • kg, 13 ft • lb)
CHECKING THE ENGINE OIL LEVEL
1.Place the machine on a level surface.
2.Start the engine, warm it up until the engine
oil has reached a normal temperature of
60 °C (140 °F), let it continue to idle for ten
seconds, and then turn the engine off.
NOTE:
To achieve the proper engine oil temperature
for an accurate oil level reading, the engine
must have first completely cooled down, and
then warmed up again for several minutes to
normal operating temperature.