Yamaha MX800V Service Manual page 40

ENGINE INSPECTION
1
2
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5
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8
9
10
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a. If the compression pressure is below the minimum
specification, pour a teaspoonful of engine oil into
the spark plug hole and measure again. Refer to
the following table.
Reading
Higher than
• Worn cylinder, piston, and piston ring(s)
without oil
• Defective piston, piston ring(s), valve(s), and
Same as
cylinder head gasket
without oil
• Improper valve timing and valve clearance
b. If the compression pressure is above the maximum
specification, check the cylinder head, valve sur-
faces and piston crown for carbon deposits.
Carbon deposits  Eliminate.
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5.
Install:
• Spark plug
Spark plug:
20 N·m (2.0 kgf·m, 15 lb·ft)
• Spark plug cap
3-2
Diagnosis