Yamaha Fazer FZ8-SA, Service Manual

Page: 266 / 610

ENGINE INSPECTION
5-1
EAS14B1052
ENGINE INSPECTION
EAS20710
MEASURING THE COMPRESSION PRES-
SURE
The following procedure applies to all of the
cylinders.
TIP
Insufficient compression pressure will result in
a loss of performance.
1. Measure:
• Valve clearance
Out of specification
→
Adjust.
Refer to “ADJUSTING THE VALVE
CLEARANCE” on page 3-5.
2. Start the engine, warm it up for several
minutes, and then turn it off.
3. Remove:
• Ignition coils
• Spark plugs
ECA13340
Before removing the spark plugs, use com-
pressed air to blow away any dirt accumu-
lated in the spark plug wells to prevent it
from falling into the cylinders.
4. Install:
• Compression gauge “1”
• Extension “2”
5. Measure:
• Compression pressure
Out of specification
→
Refer to steps (c)
and (d).
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a. Set the main switch to “ON”.
b. With the throttle wide open, crank the
engine until the reading on the compres-
sion gauge stabilizes.
WARNING
EWA39P1501
To prevent sparking the plug, remove all
ignition coil couplers and fuel injector cou-
plers before cranking the engine.
TIP
The difference in compression pressure
between cylinders should not exceed 100 kPa
(1 kg/cm², 15 psi).
c. If the compression pressure is above the
maximum specification, check the cylinder
head, valve surfaces and piston crown for
carbon deposits.
Carbon deposits
→
Eliminate.
d. If the compression pressure is below the
minimum specification, pour a teaspoonful
of engine oil into the spark plug bore and
measure again.
Refer to the following table.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
Compression gauge
90890-03081
Engine compression tester
YU-33223
Extension
90890-04136
Standard compression pres-
sure (at sea level)
1480 kPa/350 r/min (14.8 kgf/
cm²/350 r/min, 210.5 psi/350 r/
min)
Minimum–Maximum
1290–1660 kPa/350 r/min
(12.9–16.6 kgf/cm²/350 r/min,
183.5–236.1 psi/350 r/min)
Compression pressure (with oil applied into
the cylinder)
Reading
Diagnosis
Higher than without
oil Piston ring(s) wear or
damage
→
Repair.
Same as without oil
Piston, valves, cylin-
der head gasket pos-
sibly defective
→
Repair.