Yamaha XVS650 Service Manual page 76

COMPRESSION PRESSURE MEASUREMENT
II:gs
I_I
EB303060
COMPRESSION PRESSURE
MEASUREMENT
NOTE: _
Insufficient compression pressure will
result in a loss of performance.
1.Check:
• Valve clearance
Out of specification
-7
Adjust.
Refer to "VALVE CLEARANCE ADJUST-
MENT".
2.Start the engine and let it warm up for
several minutes.
3.Stop the engine.
4.Remove:
• Spark plug caps
• Spark plugs
Before removing the spark plugs, use com-
pressed air to blow away any dirt accumu-
lated in the spark plug wells, to prevent it
from falling into the cylinders.
6.Measure:
• Compression pressu re
If it exceeds the maximum pressure
allowed
~
Inspect the cylinder head,
valve surfaces and piston crown for car-
bon deposits.
If it is below the minimum pressure
-7
Squirt a few drops of oil into the affected
cylinder and measure again.
• Refer to the table below.
'. Compression gauge set:
VU-33223,90890-03081
5.Attach:
• Compression gauge
CD