Yamaha FX Nytro 2008 Manuel D'atelier page 78

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.
Compression pressure
(with oil applied into cylinder)
Reading
Higher than
without oil
Same as
without oil
Compression pressure (at sea level):
Standard:
1,500 kPa (15.0 kg/cm
at 400 r/min
Minimum:
1,400 kPa (14.0 kg/cm
at 400 r/min
Maximum:
1,600 kPa (16.0 kg/cm
at 400 r/min
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
14.2 psi).
7. Install:
• Spark plug
Spark plug:
13 Nm (1.3 m · kg, 9.4 ft · lb)
2-19
INSP
ADJ
Diagnosis
Piston ring(-s) wear or
damage → Repair.
Piston, valves, cylinder
head gasket or piston
possibly defective →
Repair.
Compression pressure (at
sea level)
2
, 213.3 psi)
2
, 199.1 psi)
2
, 227.5 psi)
2
,