Compression Pressure Measurement - Yamaha WaveRunner FX SHO Service Manual

CHK
ADJ
Power unit
6
5

Compression pressure measurement

1. Measure:
1
• Compression pressure
NOTE:
Make sure that the battery voltage is more
than 12 V.
2
3
4
Measurement steps:
1. Place the watercraft in the water.
2. Start the engine, allow it to warm up for 5
minutes, and then stop the engine.
3. Remove the engine cover 1, bolts 2,
ignition coils 3, and spark plugs 4.
NOTE:
• Slide the engine cover rearward, and then lift
the cover to remove it.
• Be careful not to get water or any other for-
eign substances in the spark plug holes.
4. Install the special service tools 5 and 6.
5. Crank the engine until the reading on the
compression gauge stabilizes.
6. Measure the compression pressure for all
cylinders according to steps 4–5.
7. If the compression pressure is below spec-
ification, squirt a few drops of engine oil
into the cylinder and measure again.
(with engine oil added into the cylinder)
Higher than without
engine oil
Same as without
engine oil
3-12
Compression pressure
(reference data):
2
610 kPa (6.1 kgf/cm , 86.8 psi)
Compression gauge extension 5:
90890-06582
Compression gauge 6:
YU-33223/90890-03160
Compression pressure
Reading
Piston ring, and
piston
Valve clearance,
valve, valve seat,
cylinder head, and
cylinder head gasket
E
1
2
3
4
5
6
7
Check
8
9