Engine; Engine Inspection; Measuring The Compression Pressure - Yamaha MX800V Service Manual

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ENGINE

ENGINE INSPECTION

MEASURING THE COMPRESSION PRESSURE

The following procedure applies to all of the cylinders.
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
NOTICE
Before removing the spark plug, use compressed air
to clean the cylinder head cover to prevent dirt from
falling into the engine.
3.
Connect:
• Engine compression tester "1"
• Extension "2"
Engine compression tester:
YU-33223
4.
Measure:
• Compression pressure
Open the throttle and crank the engine until the
needle stop rising on the engine compression tes-
ter.
Out of specification  Refer to steps (a) and (b).
Standard compression pressure:
490–640 kPa (4.9–6.4 kg/cm², 71–93 psi)
Limit:
430 kPa (4.3 kg/cm², 62 psi)
WARNING
To prevent sparking the plugs, remove all TCI units
connectors before cranking the engine.
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