Yamaha EH63 - Engine; Engine Inspection; Measuring the Compression Pressure

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ENGINE
3-1
ENGINE
ENGINE INSPECTION
MEASURING THE COMPRESSION PRESSURE
The following procedure applies to all of the cylinder
heads.
TIP
Measure the compression pressure after checking and
adjusting the valve clearance.
1. Warm up the engine for several minutes.
2. Remove:
• Spark plug cap
• Spark plug
3. Connect:
• Compression gauge “1”
• Compression gauge extension 73mm “2”
4. Measure:
• Compression pressure
Crank the engine until the needle stop rising on the
compression gauge.
Out of specification  Refer to the testing steps.
Before removing the spark plug, use compressed air
to clean the cylinder head cover to prevent dirt from
falling into the engine.
NOTICE
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Compression gauge:
90890-03081
Engine compression tester:
YU-33223
Compression gauge extension 73mm:
90890-04082, YM-04082
Standard compression pressure:
1200 kPa (12 kg/cm², 174 psi)
To prevent sparking when cranking the engine,
ground the high tension cord.
WARNING