Yamaha TMAX XP500F 2015, Service Manual, Page: 238 / 478

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 3-5.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Remove:
• Radiator cover
Refer to “GENERAL CHASSIS (2)” on page
4-8.
4. Disconnect:
• Spark plug caps
5. 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.
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 engine
until the reading on the compression gauge
stabilizes.
TIP
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 min-
imum specification, pour a teaspoonful of en-
gine oil into the spark plug bore and measure
again.
Refer to the following table.
▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲ ▲▲▲ ▲ ▲▲▲
8. Install:
• Spark plugs
9. Connect:
• Spark plug caps
10.Install:
• Radiator cover
Refer to “GENERAL CHASSIS (2)” on page
4-8.
Compression gauge
90890-03081
Engine compression tester
YU-33223
Standard compression pressure
(at sea level)
1950 kPa/470 r/min (19.5
kgf/cm²/470 r/min, 277.3 psi/470
r/min)
Minimum–maximum
1697–2184 kPa/470 r/min (17.0–
21.8 kgf/cm²/470 r/min, 241.4–
310.6 psi/470 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 cylin-
der head gasket possi-
bly defective
→
Replace.
T
R
.
.
Spark plug
13 Nm (1.3 m·kgf, 9.4 ft·lbf)