Yamaha XVS6501997, Service Manual

Page: 71 / 327

3-15
COMPRESSION PRESSURE MEASUREMENT
INSP
ADJ
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NOTE:
18 Nm (1.8 m
S
kg)
Compression pressure
(with oil applied in the cylinder)
Reading Diagnosis
Higher than
without oil
Worn or damaged pistons
Repair.
Same as
without oil
Possible defective ring(s),
valves, cylinder head gas-
ket or piston
Repair.
Compression pressure
(at sea level)
Standard:
1,100 kPa (11 kg / cm
2
, 11 bar)
Minimum:
1,000 kPa (10 kg / cm
2
, 10 bar)
Maximum:
1,200 kPa (12 kg / cm
2
, 12 bar)
Measurement steps:
D
Crank the engine with the throttle wide open
until the reading on the compression gauge
stabilizes.
To prevent sparking, ground all spark plug
leads before cranking the engine.
D
Repeat the previous steps for the other cylin-
ders.
The difference in compression pressure be-
tween the highest and lowest cylinder compres-
sion readings should not exceed 100 kPa (1
kg / cm
2
, 1 bar).
7. Install:
S
Spark plugs
S
Spark plug caps