3 - 18
CHK
ADJ
MEASURING THE COMPRESSION PRESSURE
MEASURING THE COMPRESSION
PRESSURE
NOTE:
Insufficient compression pressure will result in
a loss of performance.
1.Check:
●
Valve clearance
Out of specification
→
Adjust.
Refer to “ADJUSTING THE VALVE CLEAR-
ANCE”.
2.Start the engine and let it warm up for sev-
eral minutes.
3.Stop the engine.
4.Remove:
●
Spark plug
5.Attach:
●
Adapter
●
Compression gauge
1
Compression gauge:
P/N. YU-33223, 90890-03081
Adapter:
P/N. YU-33223-3, 90890-04082
6.Measure:
●
Compression pressure
Above the maximum pressure:
Inspect the cylinder head, valve surfaces,
and piston crown for carbon deposits.
Below the minimum pressure:
Squirt a few drops of oil into the affected cyl-
inder and measure again.
●
Refer to the table below.
Compression pressure
(with oil introduced into cylinder)
Reading
Diagnosis
Higher than
without oil
Worn or damaged piston,
rings or cylinder wall.
Same as
without oil
Defective valves or
cylinder head gasket.
Summary of Contents for YFM660RN
Page 1: ...YFM660RN YFM660RNC SERVICEMANUAL LIT 11616 14 21 5LP 28197 E0 ...
Page 33: ...2 11 SPEC Cylinder head tightening sequence Item Standard Limit MAINTENANCE SPECIFICATIONS ...
Page 45: ...2 23 SPEC OIL FLOW DIAGRAMS 1 Oil tank 2 Oil pipe 2 3 Oil pipe 1 OIL FLOW DIAGRAMS ...
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Page 111: ...3 55 CHK ADJ CHECKING THE BATTERY Charging method using a constant voltage charger ...
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