Compression Pressure - Yamaha EF1000iS Service Manual

1

COMPRESSION PRESSURE

COMPRESSION PRESSURE
NOTE:
Measure the compression after checking and
adjusting the valve clearance.
1. Warm up the engine for several minutes.
2. Remove:
3. Remove:
4. Connect:
2
5. Measure:
w
To prevent sparking when cranking the
engine, ground the high-tension cord.
Testing steps (below minimum level):
9 Squirt a few drops of oil into the cylinder.
9 Measure the compression again.
If higher than
without oil
If the same as
without oil
2-12
9 Spark plug
9 Cover
9 Compression gauge 1
9 Adapter 2
Compression gauge:
YU-33223, 90890-03081
Adapter:
YU-33223-3, 90890-04082
9 Compression
To measure the compression, pull the
recoil starter until the needle stops ris-
ing on the compression gauge.
Standard compression pressure:
400 kPa
(4 kg/cm 2 , 57 psi)
Reading
9 Worn cylinder, piston, and
piston ring
9 Defective piston, ring(s),
valve(s), and cylinder head
gasket
9 Improper valve timing and
valve clearance
INSP
ADJ
Diagnosis