Yamaha Tenere 700 2020, Service Manual

Page: 188 / 472

ENGINE INSPECTION
5-1
EAS20041
ENGINE INSPECTION
EAS30249
MEASURE 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 3-6.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Remove:
• Ignition coils
Refer to “CHECKING THE SPARK PLUGS”
on page 3-5.
4. Remove:
• Spark plugs
NOTICE
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.
5. Install:
• Extension “1”
• Compression gauge “2”
6. Measure:
• Compression pressure
Out of specification
→
Refer to steps (c) and
(d).
TIP
Due to the engine characteristics, the compres-
sion pressure is different for cylinder #1 and cyl-
inder #2.
a. Turn the main switch to “ON”.
b. With the throttle wide open, crank the en-
gine until the reading on the compression
gauge stabilizes.
WARNING
EWA12940
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
minimum specification, pour a teaspoonful
of engine oil into the spark plug bore and
measure again.
Refer to the following table.
Compression gauge extension
122mm
90890-04136
Compression gauge extension
122mm
YM-04136
Compression gauge
90890-03081
Engine compression tester
YU-33223
1
2
Compression pressure
770–990 kPa/355 r/min (7.7–9.9
kgf/cm²/355 r/min, 109.5–140.8
psi/355 r/min)
Compression pressure (#2 cylin-
der)
690–880 kPa/355 r/min (6.9–8.8
kgf/cm²/355 r/min, 98.1–125.2
psi/355 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
Pistons, valves, cylinder
head gasket or piston
ring(s) possibly defec-
tive
→
Repair.