Measuring The Compression Pressure - Yamaha YFM250RX 2008 Service Manual

MEASURING THE COMPRESSION PRESSURE

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MEASURING THE COMPRESSION
PRESSURE
The following procedure applies to the cylinder.
NOTE: NOTE:
Insufficient compression pressure will result in
a loss of performance.
1. Measure:
• 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:
• Spark plug cap
4. Remove:
• Spark plug
ECA13340
CAUTION:
Before removing the spark plug, use com-
pressed air to blow away any dirt accumu-
lated in the spark plug wells to prevent it
from falling into the cylinder.
5. Install:
• Compression gauge
• Extension
Compression gauge
90890-03081
Engine compression tester
YU-33223
Extension
90890-04082
3-17
CHK
ADJ