Yamaha YFM700RV 2009 Service Manual page 101

MEASURING THE COMPRESSION PRESSURE
5. Attach:
• extension
1
• compression gauge 1
6. Measure:
• compression pressure
Out of specification → Refer to steps (c)
and (d).
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a. Set the main switch to "ON".
b. With the throttle wide open, crank the
engine until the reading on the compression
gauge stabilizes.
WARNING
_
To prevent sparking, ground the spark plug
lead before cranking the engine.
c. If the compression pressure is above the
maximum specification, check the cylinder
head, valve surfaces and piston crown for
carbon deposits.
Carbon deposits → Eliminate.
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Compression gauge
90890-03081
Engine compression tester
YU-33223
Extension
90890-04082
Compression pressure (at sea
level)
Minimum
392 kPa (3.92 kg/cm
Standard
450 kPa (4.5 kg/cm
Maximum
504 kPa (5.04 kg/cm
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CHK
ADJ
2
, 55.8 psi)
2
, 64.0 psi)
2
, 71.7 psi)
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