20 Most Recent 2003 Yamaha YZ 125 Questions & Answers


Hi, Dave and the usual suspects are:
1. Fuel tank empty.
2. The fuel tank has old dead gas.
3. Fuel tank bottom contaminated with ethanol sludge, dirt, water, rust, etc.
4. Fuel supply valve/petcock turned off.
5. Fouled spark plugs.
6. Engine flooded as a result of overuse of the choke.
7. Vacuum hose to the fuel supply valve/petcock disconnected, broken, cracked, or pinched.
8. Fuel valve/petcock or filter clogged.
9. Fuel line to carburetor or throttle body pinched, kinked or blocked.
10. Carburetor float stuck.
11. Fuel injectors clogged.
12. Fuel injectors stuck open.
13. Quick disconnect check ball stuck.
14. Compression below 75 PSI.
15. A stuck-bent-burnt valve.
16. Severely discharged or a damaged battery should have 12.5 volts or more and be able to pass a proper "LOAD" test if necessary, you may have a cursory reading of 12.5 volts or more but little or zero amperage the battery is faulty and must be replaced, AGM batteries fail in this scenario more so than lead-acid batteries.
17. Check battery terminals for damage or corrosion, check the battery cables at "BOTH" ends for loose, corroded, or broken connectors, "INSIDE" and outside the cable harness, perform connector wiggle test and check cables with an ohmmeter if necessary.
18. Loose or corroded wire connection at the coil or plug between ignition sensor and ECM module.
19. Spark plug cables in bad condition and shorting check for spark leakage in the dark, cable connections loose, or connected to the wrong cylinders.
20. Ignition timing incorrect due to a faulty ignition coil, ignition module or MAP, CMP, CKP, O2, TPS, ETP, IAC sensors.
21. Faulty neutral, clutch, kickstand safety switch.
22. Faulty fuel pump or fuse or relay.
23. A stuck bent or burnt valve.
24. Tilt sensor needs a reset.
25. Security system not disarming alarm needs a reset.
26. Check for engine trouble codes.
27. Faulty run stop switch.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
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2003 Yamaha YZ... | Answered on Dec 03, 2017


Hi, Anonymous I feel your pain you just dropped a ton of "DRACHMA" on rebuilding all or part of your engine and a couple of hours or days later it dies or locks up and you want me to tell you how much it will cost to fix. Unfortunately due to the magnitude of yesterday's solar flare the batteries in my crystal ball are dead and the circuitry in my mental telepathy headset was melted. Let me break it down for you.
1. Was the work done by an experienced trained professional technician or someone with good intentions that was not qualified to hold a wrench?
2. Was the proper break in procedure explicitly followed using the proper break in oil and changed as directed?
3. If your bike is used for off road abuse or competition there is no warranty in most cases.
4. If you have a street bike that had performance goodies installed no warranty in most cases.
For more information about your issue and valuable "FREE" downloads that you will need please click on the blue links below. Good luck and have a wonderful day.
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2003 Yamaha YZ... | Answered on May 27, 2017


Hi, Nbt_kmt for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere zero $ you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the blue links below. Good luck and have a wonderful day.
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2003 Yamaha YZ... | Answered on Feb 22, 2017


Hi, Ihyo and the usual suspects are:
1. Fuel tank empty.
2. Fuel supply valve/petcock turned off.
3. Fouled spark plugs.
4. Engine flooded as a result of overuse of the enricher.
5. Vacuum hose to the fuel supply valve/petcock disconnected, broken, cracked, or pinched.
6. Fuel valve/petcock or filter clogged.
7. Fuel line to the carburetor or throttle body pinched or kinked.
8. Carburetor float stuck.
9. Fuel injectors clogged.
10. Severely discharged or damaged battery you need 12.5 volts or better and be able to pass a load test if necessary.
11. Check battery terminals for damage or corrosion, check the battery cables at "BOTH" ends for loose, corroded, or broken connectors, "INSIDE" and outside the cable harness, perform connector wiggle test and check cables with an ohmmeter if necessary.
12. Loose or corroded wire connection at the coil, battery or plug between ignition sensor and CDI box.
Spark plug cables in bad condition and shorting check for leakage in the dark, cable connections loose, or connected to the wrong cylinders.
13. Ignition timing incorrect due to a faulty MAP, CKP, O2, TPS, sensors.
14. Faulty neutral, clutch lever, or kickstand safety switch.
15. Faulty fuel pump or fuse or relay.
16. Faulty CDI box.
17. A stuck bent or burnt valve.
18. Tip over sensor needs a reset.
19. Check for engine trouble codes.
For more information about your issue and valuable "FREE" downloads that you will need please click on the blue links below. Good luck and have a wonderful day.
98 YZ 125 won start
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2003 Yamaha YZ... | Answered on Feb 22, 2017


Hi, David and the usual suspects are:
1. Severely discharged or a damaged battery, should have 12.5 volts or better and be able to pass a load test if necessary.
2. Failed alternator/generator and or voltage regulator.
3. Loose or corroded battery terminals and or cables especially the "NEGATIVE" cable, look for loose, corroded, or broken connectors inside the cable harness at "BOTH" ends.
4. Failed main circuit breaker or ignition switch, check for loose connections and continuity.
5. Failed system and or ignition relay, check for continuity.
6. Failed ignition coil, ignition/electronic module.
7. Failed CKP, CPS, CMP, MAP, TPS, or BAS sensor, corroded, loose or broken wire connector pins/sockets.
8. Throttle cables and or idle speed improperly adjusted hot idle speed should be 950 RPM to 1000 RPM.
9. Air/fuel mixture screw improperly adjusted.
10. Accelerator pump damaged or not working.
11. Water or dirt in the fuel system, carburetor or filter.
12. Restricted, blocked or kinked fuel line.
13. Fuel tank empty.
14. The gas cap is not venting properly or fuel tank venting system blocked.
15. A failed fuel pump, pressure regulator and or fuel injectors.
16. Vacuum line from intake manifold to petcock broken, cracked, or not attached, carburetor vent line plugged.
17. Needle and seat stuck closed in the float bowl.
For more information about your issue and valuable "FREE" downloads that you need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Aug 01, 2016


Hi, Anonymous for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
Dirt Rider Magazine
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Yamaha YZ125T1 Owner Service Manual
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2003 Yamaha YZ... | Answered on Jul 28, 2016


Hi, Jakephair for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Billywill946 for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Morgan_honda and the usual suspects are:
1. Damaged or restricted fuel tank venting system.
2. Loose float bowl screws.
3. Damaged float bowl o-ring.
4. improper fuel level in the float bowl.
5. Worn or dirty inlet valve or seat.
6. Damaged or leaking float assembly.
7. Particle contamination in inlet fitting cavity.
For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have nice a day.
2003 YZ125 Carb Overflow Hose Is Leaking Yamaha 2 Stroke
Oakys Garage How to clean overflowing Carb Carburetor Part 1
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Weskeys for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
Dirt Rider Magazine
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Reggiemorale for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Drd4 hard to say my DYNO got repossessed for more information about your question and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Wannagofishi for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Dustintubbs for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Jeds351 I would love to help you with your engine or chassis noise but I just loaned my brand new pair of listening ears to your local dealer's chief technician so he could take your bike for a test ride and give you his professional opinion and estimate about your noise and repair cost. For more information about your issue and valuable "FREE" downloads that you need please click on the links below. Good luck and have nice a day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Suttyturbo for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Cows_go_moo for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Customcre8 it is an overflow tube do not plug or attach for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016


Hi, Terry156 ABSOLUTELY for more information about your question and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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2003 Yamaha YZ... | Answered on Jul 19, 2016

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