5-6
ENGINE INSPECTION
EAS20041
ENGINE INSPECTION
EAS30249
MEASURE THE COMPRESSION PRESSURE
The following procedure applies to all of the cyl-
inders.
Insufficient compression pressure will result in a
loss of performance.
1. Measure:
• Valve clearance
Out of specification Adjust.
Refer to “ADJUSTING THE VALVE CLEAR-
ANCE” on page 3-5.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Remove:
• Bottom side cowling
• Side panel
• Radiator cover
Refer to “GENERAL CHASSIS (1)” on
page 4-1.
4. Disconnect:
• Spark plug cap
5. Remove:
• Spark plug
ECA13340
Before removing the spark plugs, use com-
pressed air to blow away any dirt accumulat-
ed in the spark plug wells to prevent it from
falling into the cylinders.
6. Install:
• Compression gauge “1”
7. Measure:
• Compression pressure
Out of specification
Refer to steps (c) and (d).
a. Push the ON/start switch.
b. With the throttle wide open, crank the en-
gine until the reading on the compression
gauge stabilizes.
The difference in compression pressure be-
tween cylinders should not exceed 100 kPa
(1 kgf/cm², 14 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.
8. Install:
• Spark plugs
9. Connect:
• Spark plug cap
10.Install:
• Radiator cover
• Side panel
• Bottom side cowling
Refer to “GENERAL CHASSIS (1)” on
page 4-1.
Compression gauge
90890-03081
Engine compression tester
YU-33223
Compression pressure
1653–2128 kPa/360 r/min
(16.5–21.3 kgf/cm²/360 r/min,
235.1–302.7 psi/360 r/min)
Compression pressure (with oil applied into
the cylinder)
Reading Diagnosis
Higher than without oil
Piston ring(s) wear or
damage Replace.
Same as without oil Piston, valves or cyl-
inder head gasket
possibly defective
Replace.
Spark plug
13 N·m (1.3 kgf·m, 9.6 lb·ft)
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