ENGINE (YP125R)
3-11
EAS37P1093
MEASURING THE COMPRESSION
PRESSURE
TIP
Insufficient compression pressure will result in a
loss of performance.
1. Remove:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.
2. Measure:
• Valve clearance
Out of specification
→
Adjust.
Refer to “ADJUSTING THE VALVE CLEAR-
ANCE” on page 3-6.
3. Start the engine, warm it up for several min-
utes, and then turn it off.
4. Disconnect:
• Spark plug cap
5. Remove:
• Spark plug
NOTICE
ECA37P1043
Before removing the spark plug, use com-
pressed air to blow away any dirt accumulat-
ed in the spark plug well to prevent it from
falling into the cylinder.
6. Install:
• Compression gauge “1”
7. 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
EWA37P1019
To prevent sparking, ground the spark plug
lead before cranking the engine.
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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8. Install:
• Spark plug
9. Connect:
• Spark plug cap
10.Install:
• Storage box
Refer to “GENERAL CHASSIS” on page 4-1.
Compression gauge
90890-03081
Engine compression tester
YU-33223
1
Standard compression pressure
(at sea level)
550 kPa/680 r/min (5.5
kgf/cm²/680 r/min, 78.2 psi/680
r/min)
Minimum–maximum
480–620 kPa (4.8–6.2 kgf/cm²,
68.3–88.2 psi)
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, cylin-
der head gasket or
piston ring(s) possi-
bly defective
→
Re-
pair.
T
R
.
.
Spark plug
13 Nm (1.3 m·kgf, 9.4 ft·lbf)
Summary of Contents for XMAX 125
Page 1: ...SERVICE MANUAL 2010 37P F8197 E0 YP125R YP250R ...
Page 6: ......
Page 8: ......
Page 28: ...SPECIAL TOOLS 1 19 ...
Page 30: ...COOLING SYSTEM DIAGRAMS YP250R 2 73 CABLE ROUTING YP250R 2 75 ...
Page 31: ......
Page 55: ...LUBRICATION POINTS AND LUBRICANT TYPES YP125R 2 24 ...
Page 62: ...CABLE ROUTING YP125R 2 31 Front fork front view A 1 1 1 1 2 2 2 3 4 5 6 7 ...
Page 66: ...CABLE ROUTING YP125R 2 35 Engine right side view A 7 3 2 2 2 1 3 4 5 6 7 ...
Page 70: ...CABLE ROUTING YP125R 2 39 Engine left side view 2 1 3 4 A 3 ...
Page 72: ...CABLE ROUTING YP125R 2 41 Handlebar top view A 1 2 3 4 4 5 6 7 8 9 10 11 12 13 14 15 16 17 ...
Page 76: ...CABLE ROUTING YP125R 2 45 Tail brake light top view 2 1 3 4 B A 1 5 6 ...
Page 103: ...LUBRICATION POINTS AND LUBRICANT TYPES YP250R 2 72 ...
Page 108: ...CABLE ROUTING YP250R 2 77 Front fork front view 1 1 2 3 4 5 6 7 1 2 A 1 2 ...
Page 112: ...CABLE ROUTING YP250R 2 81 Engine right side view A 7 3 2 2 2 1 3 4 5 6 7 8 B ...
Page 116: ...CABLE ROUTING YP250R 2 85 Engine left side view 2 1 3 4 5 6 B A 3 7 ...
Page 118: ...CABLE ROUTING YP250R 2 87 Handlebar top view A 1 2 3 4 4 5 6 7 8 8 9 10 11 12 13 14 15 16 17 ...
Page 122: ...CABLE ROUTING YP250R 2 91 Tail brake light top view 2 1 3 4 B A 1 5 6 8 7 ...
Page 124: ...CABLE ROUTING YP250R 2 93 ...
Page 127: ......
Page 172: ...ELECTRICAL SYSTEM 3 45 ...
Page 175: ......
Page 240: ...REAR SHOCK ABSORBER ASSEMBLIES AND SWINGARM 4 65 ...
Page 245: ......
Page 305: ...CRANKSHAFT YP125R 5 60 a 1 ...
Page 366: ...CRANKSHAFT YP250R 5 121 ...
Page 394: ...THROTTLE BODY 7 11 ...
Page 397: ......
Page 411: ...CHARGING SYSTEM 8 14 ...
Page 423: ...SIGNALING SYSTEM 8 26 ...
Page 427: ...COOLING SYSTEM 8 30 ...
Page 453: ...FUEL INJECTION SYSTEM 8 56 ...
Page 457: ...FUEL PUMP SYSTEM 8 60 ...
Page 466: ...IMMOBILIZER SYSTEM 8 69 a Light on b Light off ...
Page 467: ...IMMOBILIZER SYSTEM 8 70 ...
Page 495: ......
Page 496: ...YAMAHA MOTOR ESPAÑA S A ...