ENGINE
3-9
4. Remove:
• Spark plug
ECA13340
Before removing the spark plug, use com-
pressed air to blow away any dirt accumu-
lated in the spark plug wells to prevent it
from falling into the cylinder.
5. Install:
• Compression gauge “1”
• Extension “2”
6. Measure:
• Compression pressure
Out of specification
→
Refer to steps (c)
and (d).
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Set the main switch to “ON”.
b. With the throttle wide open, crank the
engine until the reading on the compres-
sion gauge stabilizes.
WARNING
EWA4D3F002
To prevent sparking, ground 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
minimum specification, pour a teaspoonful
of engine oil into the spark plug bore and
measure again.
Refer to the following table.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
7. Install:
• Spark plug
8. Connect:
• Spark plug cap
EAS28920
CHECKING THE ENGINE OIL LEVEL
1. Place the vehicle on a level surface.
2. Start the engine, warm it up for several
minutes, and then turn it off.
3. Check:
• Engine oil level
The engine oil level should be between
the minimum level mark “a” and maxi-
mum level mark “b”.
Below the minimum level mark
→
Add the
recommended engine oil to the proper
level.
TIP
• Before checking the engine oil level, wait a
few minutes until the oil has settled.
Compression gauge
90890-03081
Engine compression tester
YU-33223
Extension
90890-04082
Standard compression pressure
(at sea level)
Standard
1100 kPa/720 r/min (11.0 kgf/
cm
2
/720 r/min, 156.5 psi/720 r/
min)
Maximum
1300 kPa/720 r/min (13.0 kgf/
cm
2
/720 r/min, 188.6 psi/720 r/
min)
Minimum
900 kPa/720 r/min (9.0 kgf/
cm
2
/720 r/min, 130.5 psi/720 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
Piston, valves, cylin-
der head gasket or
piston possibly defec-
tive
→
Repair.
Spark plug
18 Nm (1.8 m·kg, 13 ft·lb)
Summary of Contents for 2009 YFM25RY
Page 1: ...SERVICE MANUAL YFM25RY YFM25RSEY YFM25RSE2Y 4D3 28197 11 LIT 11616 22 09 2009 ...
Page 8: ......
Page 39: ...LUBRICATION POINTS AND LUBRICANT TYPES 2 20 ...
Page 42: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 23 EAS20410 LUBRICATION DIAGRAMS ...
Page 44: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 25 ...
Page 46: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 27 ...
Page 47: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 2 28 1 Oil cooler 2 Oil hose 1 3 Oil hose 2 ...
Page 48: ...CABLE ROUTING 2 29 EAS20430 CABLE ROUTING ...
Page 50: ...CABLE ROUTING 2 31 ...
Page 52: ...CABLE ROUTING 2 33 ...
Page 54: ...CABLE ROUTING 2 35 ...
Page 56: ...CABLE ROUTING 2 37 ...
Page 58: ...CABLE ROUTING 2 39 ...
Page 60: ...CABLE ROUTING 2 41 ...
Page 62: ...CABLE ROUTING 2 43 ...
Page 65: ......
Page 143: ...HANDLEBAR 4 42 Throttle cable free play 2 0 4 0 mm 0 08 0 16 in ...
Page 162: ...CHAIN DRIVE 4 61 ...
Page 165: ......
Page 240: ...CARBURETOR 6 9 ...
Page 242: ...IGNITION SYSTEM 7 1 EAS27090 IGNITION SYSTEM EAS27100 CIRCUIT DIAGRAM ...
Page 246: ...ELECTRIC STARTING SYSTEM 7 5 EAS27160 ELECTRIC STARTING SYSTEM EAS27170 CIRCUIT DIAGRAM ...
Page 252: ...CHARGING SYSTEM 7 11 EAS27200 CHARGING SYSTEM EAS27210 CIRCUIT DIAGRAM ...
Page 255: ...CHARGING SYSTEM 7 14 ...
Page 256: ...LIGHTING SYSTEM 7 15 EAS27240 LIGHTING SYSTEM EAS27250 CIRCUIT DIAGRAM ...
Page 260: ...SIGNALING SYSTEM 7 19 EAS27270 SIGNALING SYSTEM EAS27280 CIRCUIT DIAGRAM ...
Page 264: ...CARBURETOR HEATING SYSTEM 7 23 EAS27490 CARBURETOR HEATING SYSTEM EAS27500 CIRCUIT DIAGRAM ...
Page 267: ...CARBURETOR HEATING SYSTEM 7 26 ...
Page 268: ...ELECTRICAL COMPONENTS 7 27 EAS27972 ELECTRICAL COMPONENTS ...
Page 270: ...ELECTRICAL COMPONENTS 7 29 EAS27980 CHECKING THE SWITCHES ...
Page 284: ...ELECTRICAL COMPONENTS 7 43 ...
Page 291: ......
Page 292: ...YAMAHA MOTOR CO LTD 2500 SHINGAI IWATA SHIZUOKA JAPAN ...
Page 293: ...WIRING DIAGRAM YFM25RY YFM25RSEY YFM25RSE2Y ...