Yamaha Rhino 450 YXR45FAV, Service Manual, Page: 88 / 413

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CHK
ADJ
MEASURING THE COMPRESSION PRESSURE
4. Remove:
• spark plug
5. Attach:
• adapter
• compression gauge
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6. Measure:
• compression pressure
Above the maximum pressure:
Check the cylinder head, valve surfaces,
and piston crown for carbon deposits.
Below the minimum pressure:
Squirt a few drops of oil into the affected
cylinder and measure again.
Refer to the table below.
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Crank over the engine with the electric starter
(be sure the battery is fully charged) with the
throttle wide-open until the compression read-
ing on the gauge stabilizes.
Engine compression tester
P/N. YU-33223
Compression gauge
P/N. 90890-03081
Extension
P/N. 90890-04082
Compression pressure
(with oil introduced into cylinder)
Reading Diagnosis
Higher than
without oil Worn or damaged piston
ring(s)
Same as with-
out oil
Defective piston ring(s),
valve(s), cylinder head
gasket or piston is pos-
sible.
Compression pressure
(at sea level)
Standard:
1,270 kPa
(12.70 kg/cm
2
, 180.6 psi)
at 700 r/min
Minimum:
1,105 kPa
(11.05 kg/cm
2
, 157.1 psi)
at 700 r/min
Maximum:
1,422 kPa
(14.22 kg/cm
2
, 202.2 psi)
at 700 r/min
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