Yamaha WaveRunner GP1300R Supplementary Service Manual page 156

POWR
COMPRESSION PRESSURE MEASUREMENT
6. Measure:
• Compression pressure
Out of specification → Refer to steps (b)
and (c).
Minimum compression pressure
(reference data):
640 kPa (6.4 kgf/cm
Measurement steps:
a. With the throttle wide open, crank the
engine until the reading on the compres-
sion gauge stabilizes.
WARNING
To prevent sparking, ground all spark
plug leads before cranking the engine.
b. If the compression pressure is extremely
high, check the cylinder head and piston
crown for carbon deposits.
Carbon deposits → Eliminate.
c. If the compression pressure is below
specification and the compression pres-
sure for each cylinder is unbalanced,
squirt a few drops of oil into the cylinder
and measure the compression pressure
again.
Refer to the following table.
Compression pressure
(with oil applied to the cylinder)
Reading
Higher than
without oil
Same as without
oil
7. Install:
• Spark plugs
Spark plug:
25 N • m (2.5 kgf • m, 18 ft • lb)
5-2
E
2
, 91 psi)
Diagnosis
Piston ring wear,
piston wear or
damage → Replace.
Cylinder head gas-
ket or piston possi-
bly defective →
Replace.