Yamaha XT250X 2008, Service Manual, Page: 65 / 282

ENGINE
3-10
6. 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.
WARNING
EWA12960
To prevent sparking, ground the spark plug
lead before cranking the engine.
NOTE:
●
Make use the battery is fully charged when tak-
ing measurements.
●
Make sure there is no compression leakage
from the connecting section of the compres-
sion gauge.
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.
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7. Install:
●
Spark plug
8. Connect:
●
Spark plug cap
EAS20730
CHECKING THE ENGINE OIL LEVEL
1. Stand the vehicle on a level surface.
NOTE:
●
Place the vehicle on a suitable stand.
●
Make sure the vehicle is upright.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Check:
●
Engine oil level
The engine oil level should be between the
minimum level mark “a” and maximum level
mark “b”.
Below the minimum level mark
→
Add the
recommended engine oil to the proper level.
Compression gauge
90890-03081
Engine compression tester
YU-33223
Standard compression pressure
1200 kPa (12.0 kg/cm
2
/300 rpm)
Minimum compression pressure
1050 kPa (10.5 kg/cm
2
/300 rpm)
Maximum compression pressure
1300 kPa (13.0 kg/cm
2
/300 rpm)
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, cylinder
head gasket or pis-
ton possibly defec-
tive
→
Repair.
Spark plug
18 Nm (1.8 m•kg, 13 ft•lb)
T
R
.
.
a
b
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