Yamaha EH63 Service Manual page 46

ENGINE INSPECTION
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Testing steps (below the minimum specification):
a. Squirt a few drops of oil into the cylinder.
b. Measure the compression again.
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
Testing steps (above the maximum specification):
a. Check the cylinder head, valve surfaces, and pis-
ton crown for carbon deposits.
Carbon deposits  Eliminate.
5.
Install:
• Spark plug
Spark plug:
13 N·m (1.3 kgf·m, 9.6 lb·ft)
• Spark plug cap
3-2
Diagnosis