Measuring The Compression Pressure - Yamaha XVS250 2001 Service Manual

MEASURING THE COMPRESSION PRESSURE

EAS00065
MEASURING THE COMPRESSION PRES-
SURE
The following procedure applies to all of the cyl-
inders.
NOTE:
Insufficient compression pressure will result in a
loss of performance.
1. Measure:
S valve clearance
Out of specification  Adjust.
Refer to "ADJUSTING THE VALVE CLEAR-
ANCE".
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Disconnect:
S spark plug cap
4. Remove:
S spark plug
CAUTION:
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.
5. Install:
S compression gauge 1
Compression gauge set
90890-03081
6. Measure:
S compression pressure
Above the maximum pressure  Inspect 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.
3-15
CHK
ADJ