Engine Inspection; Measuring The Compression Pressure - Yamaha XT1200Z 2010 Service Manual

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EAS23P1087

ENGINE INSPECTION

EAS20710
MEASURING THE COMPRESSION
PRESSURE
The following procedure applies to all of the cyl-
inders.
TIP
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:
• Air filter case
Refer to "GENERAL CHASSIS" on page 4-1.
4. Disconnect:
• Ignition coil couplers "1"
5. Remove:
• Ignition coils "2"
2
6. Remove:
• Spark plug
ECA13340
NOTICE
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:
• Extension "1"
• Compression gauge "2"
Extension
90890-04136
Compression gauge
90890-03081
Engine compression tester
YU-33223
email: info@motomatrix.co.uk
2
1
1
ENGINE INSPECTION
2
8. Measure:
• Compression pressure
Out of specification → Refer to steps (c) and
(d).
Standard compression pressure
(at sea level)
680 kPa/250 r/min (6.8
kgf/cm²/250 r/min, 96.7 psi/250
r/min)
Minimum–maximum
590–760 kPa (5.9–7.6 kgf/cm²,
83.9–108.1 psi)
M MMM M MMM M M MMM M
a. Turn the main switch to "ON".
b. With the throttle wide open, crank the engine
until the reading on the compression gauge
stabilizes.
EWA12940
WARNING
To prevent sparking, ground all spark plug
leads before cranking the engine.
TIP
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.
5-1
1
M MMM M M MMM M M MMM M MMM