ENGINE INSPECTION
5-1
EAS1MC1068
ENGINE INSPECTION
EAS20710
MEASURING 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:
• Rider seat
Refer to “GENERAL CHASSIS” on page 4-1.
• Fuel tank
Refer to “FUEL TANK” on page 7-1.
• T-bar
Refer to “GENERAL CHASSIS” on page 4-1.
4. Disconnect:
• Ignition coil couplers
5. Remove:
• Ignition coils
6. 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.
7. Install:
• Compression gauge “1”
• Extension “2”
8. 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 compression gauge
stabilizes.
The difference in compression pressure be-
tween cylinders should not exceed 100 kPa (1
kg/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 min-
imum specification, pour a teaspoonful of en-
gine 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 pressure
(at sea level)
1600 kPa/400 r/min (16.0
kgf/cm²/400 r/min, 227.6 psi/400
r/min)
Minimum-maximum
1390–1790 kPa (13.9–17.9
kgf/cm², 197.7–254.6 psi)
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