Yamaha FX10X 2008, Service Manual

Page: 35 / 411

2-18
INSP
ADJ
COMPRESSION PRESSURE MEASUREMENT
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 cylinder and
measure again.
Refer to the following table.
Measurement steps:
• Set the engine stop switch to “RUN” and turn
the main switch to “START”.
• With the throttle wide open, crank the engine
until the reading on the compression gauge sta-
bilizes.
WARNING
To prevent sparking, disconnect all ignition coil
couplers before cranking the engine.
NOTE:
The difference in compression pressure between
cylinders should not exceed 100 kPa (1 kg/cm
2
,
14.2 psi).
7. Install:
• Spark plug
Compression pressure
(with oil applied into cylinder)
Reading Diagnosis
Higher than
without oil Piston ring(-s) wear or
damage
→
Repair.
Same as
without oil
Piston, valves, cylinder
head gasket or piston
possibly defective
→
Repair.
Compression pressure (at
sea level)
Compression pressure (at sea level):
Standard:
1,500 kPa (15.0 kg/cm
2
, 213.3 psi)
at 400 r/min
Minimum:
1,400 kPa (14.0 kg/cm
2
, 199.1 psi)
at 400 r/min
Maximum:
1,600 kPa (16.0 kg/cm
2
, 227.5 psi)
at 400 r/min
T
R
.
.
Spark plug:
13 Nm (1.3 m · kg, 9.4 ft · lb)