TROUBLESHOOTING
8-1
EAS28451
TROUBLESHOOTING
EAS28460
GENERAL INFORMATION
TIP
The following guide for troubleshooting does
not cover all the possible causes of trouble. It
should be helpful, however, as a guide to basic
troubleshooting. Refer to the relative proce-
dure in this manual for checks, adjustments,
and replacement of parts.
EAS28470
STARTING FAILURES
Engine
1. Cylinder and cylinder head
• Loose spark plug
• Loose cylinder head or cylinder
• Damaged cylinder head gasket
• Damaged cylinder gasket
• Worn or damaged cylinder
• Incorrect valve clearance
• Improperly sealed valve
• Incorrect valve-to-valve-seat contact
• Incorrect valve timing
• Faulty valve spring
• Seized valve
2. Piston and piston rings
• Improperly installed piston ring
• Damaged, worn or fatigued piston ring
• Seized piston ring
• Seized or damaged piston
3. Air filter
• Improperly installed air filter
• Clogged air filter element
4. Crankcase and crankshaft
• Improperly assembled crankcase
• Seized crankshaft
Fuel system
1. Fuel tank
• Empty fuel tank
• Clogged fuel strainer
• Clogged fuel tank breather hose
• Clogged rollover valve
• Deteriorated or contaminated fuel
2. Fuel cock
• Clogged or damaged fuel hose
3. Carburetor
• Deteriorated or contaminated fuel
• Clogged pilot jet
• Clogged pilot air passage
• Sucked-in air
• Damaged float
• Worn needle valve
• Improperly installed needle valve seat
• Incorrect fuel level
• Improperly installed pilot jet
• Clogged starter jet
• Faulty starter plunger
• Choke valve malfunction
Electrical system
1. Battery
• Discharged battery
• Faulty battery
2. Fuse
• Blown, damaged or incorrect fuse
• Improperly installed fuse
3. Spark plug
• Incorrect spark plug gap
• Incorrect spark plug heat range
• Fouled spark plug
• Worn or damaged electrode
• Worn or damaged insulator
• Faulty spark plug cap
• Wire between terminals broken
4. Ignition coil
• Cracked or broken ignition coil body
• Broken or shorted primary or secondary
coils
• Faulty spark plug lead
5. Ignition system
• Faulty CDI unit
• Faulty pickup coil
• Faulty stator coil
• Broken generator rotor woodruff key
6. Switches and wiring
• Faulty main switch
• Faulty engine stop switch
• Broken or shorted wiring
• Faulty neutral switch
• Faulty start switch
• Faulty clutch switch
• Improperly grounded circuit
• Loose connections
7. Starting system
• Faulty starter motor
• Faulty starter relay
• Faulty starting circuit cut-off relay
• Faulty starter clutch
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 ...