Yamaha DT 125 R - Recent Questions, Troubleshooting & Support


SOUNDS LIKE IT COULD BE THE SAFETY SWITCH FOR THE KICK STAND ,IF THE SWITCH HAS BEEN DAMAGED IT WILL START UP FINE AND WHEN PUT IN TO GEAR AND CLUTCH IS RELEASED IT WILL DIE.(This is a safety feature)

If that don't fix,Please post back

Please rate this fixya solution

2000 Yamaha DT... | Answered on Jan 17, 2020


Hi, Mel and the usual suspects are:
1. Fuel cap or fuel tank is not venting properly.
2. Fuel filter clogged.
3. Fuel line pinched or kinked.
4. Vacuum line from the petcock to intake manifold cracked.
5. Float needle and seat sticking.
6. Float level too low.
7. Carburetor bowl vent line clogged/blocked/pinched.
8. Idle adjusting screw set too low or too high.
9. Air/fuel mixture screw set too lean.
10. Idle port, transfer ports, slow air jet clogged.
11. Slow fuel jet clogged.
12. Faulty fuel pump.
13. Faulty auto choke or wiring connection.
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.
https://yamahaclub.com/forums/topic/43346-dt125r-will-only-run-on-choke
WHY your motorcycle only runs on CHOKE
https://www.manualslib.com/manual/1203458/Yamaha-Dt125re-2005.html#product-DTR%20125
https://www.partsfish.com/page/oem-parts-for-yamaha
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2003 Yamaha DT... | Answered on May 15, 2019


In the center of the under side of the motor/oil pan, you will see a diamond shaped plate held on by two screws/bolts and having a single wire coming out of it.

Yamaha DT 125 R... | Answered on Apr 04, 2019


Hi, Joseph and the usual suspects are:
1. Engine oil level and SAE weight are too low or not circulating.
2. Insufficient or blocked airflow over the engine.
3. Heavy combustion chamber carbon deposits.
4. Ignition timing retarded due to a faulty MAP, CKP, or CMP sensor.
5. Carburetor jetted too lean.
6. Leaking intake or exhaust valve.
7. Clutch slipping, brakes dragging, heavy load, towing a trailer.
8. Idling too long without moving.
9. Constant hot weather temperatures, mountain, or desert riding conditions consider adding an oil cooler and or cylinder head cooler.
10. Ignition timing retarded.
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.
Overheating DT125R Help pls
Overheating Dt125R
Yamaha DT125RE 2005 Service Manual
https://www.partsfish.com/page/oem-parts-for-yamaha
YAMAHA DT125R Owner Manual

2002 Yamaha DT... | Answered on Nov 14, 2018


Hi, Abdoulie and the usual suspects are:
1. Clutch not adjusted properly.
2. Primary chaincase overfilled with lubricant.
3. Corners wore off shifter clutch dogs.
4. Shifter return spring bent or broken.
5. Bent shifter rod.
6. A loose shift lever on shifter shaft.
7. Shifter forks sprung.
8. Shifter pawl needs adjusting.
9. Heel/toe shifter coming in contact with the floorboard.
10. Transmission oil too heavy.
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.
1974 dt125 shifter problems HELP
Only when hot can find neutral and hard to shift Yamaha R1 Forum YZF R1...
Yamaha DT125 DT125R 1988 2002 Service Repair Workshop Manual Download... $15
https://www.partsfish.com/page/oem-parts-for-yamaha
YAMAHA DT125R Owner Manual

2000 Yamaha DT... | Answered on Oct 01, 2018


Hi, David and the usual suspects are:
1. 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.
2. 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.
3. Spark plugs in bad condition or partially fouled.
4. Spark plug cables in bad condition and leaking check for spark leakage in the dark
5. Spark plug gap too close or too wide.
6. Faulty ignition coil, module, and or sensor.
7. Loose, dirty, or corroded ignition module connector at crankcase.
8. Faulty CKP or CMP, MAP, ETS, ATS, TPS, O2 sensor.
9. Dirty air filter.
10. Intake air leak.
11. Water, dirt, or rust in the fuel system.
12. Carburetor contaminated, sticky float, plugged jets.
13. Carburetor has oil in the bowl due to excessive oil in pre-mix.
14. Carburetor vacuum diaphragm torn, cracked, not seated or installed improperly.
15. Multiple carburetors out of sync.
16. Fuel filter clogged.
17. Old or contaminated fuel.
18. Fuel tank vent system plugged or carb vent line closed off.
19. Gas cap diaphragm valve faulty.
20. Vacuum line from intake manifold to fuel valve is broken, cracked, pinched, or missing.
21. Carburetor controls misadjusted.
22. Incorrect valve timing.
23. Valve springs floating, weak, or broken.
24. Damaged intake or exhaust valve.
25. Incompatible performance parts.
26. The control module may be in "LIMP" mode
27. Check for engine trouble codes.
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.
https://www.visordown.com/forum/workshop/yamaha-dt125r-engine-problems
Why is the engine bogging under acceleration Suzuki FA50 Moped
Yamaha DT125 DT125R 1988 2002 Workshop Repair Service Manual Download... $15
https://www.partsfish.com/page/oem-parts-for-yamaha
YAMAHA DT125R Owner Manual

2000 Yamaha DT... | Answered on Jul 07, 2018


Hi, Anonymous engines are either 2t or 4t, the vast majority of service, parts fiche, and owners manuals on the internet are "FREE" to download and all service manuals contain wiring diagrams in the back pages. The rest usually charge a modest fee of $15 and there is a handful of obscure, rare, obsolete, and very old models that are no longer or never were available and some were never printed in English. The Indian and Philippine markets are usually in E-book format only, for these rare occasions I shall look on eBay and find the cheapest one available. Most of the manuals will cover your exact make, model, and year otherwise one will be provided that comes as close as possible to your bike and will have most of the same info that an exact manual would have. If there is no $ sign after the manual link it is free to download.
To download your manual for viewing or printing please click on the blue links below. Good luck and have a wonderful day
Yamaha DT125RE 2005 Service Manual
https://www.partsfish.com/page/oem-parts-for-yamaha
YAMAHA DT125R Owner Manual
Yamaha DT125RE
Yamaha DT125 Wikipedia

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2003 Yamaha DT... | Answered on Apr 25, 2018


Hi, Anonymous for this scenario you will need your service manual that has all fastener torque specs and a wiring diagram on the back pages, parts fiche, and owners manual if you can't find the best tool you ever bought for your Yamaha, despair not, for a mere zero $0 you can download another one.
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.
Torque Specs
need 78 dt175 head bolt torque specs
Yamaha DT100A 1974 Service Manual includes 125
https://www.partsfish.com/page/oem-parts-for-yamaha
http://www.dt125.cz/download/Owners_Manual-DT125R.pdf

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Yamaha DT 125 R... | Answered on Apr 06, 2018


Hi, Tim for this scenario you will need your service manual that has all fastener torque specs and a wiring diagram on the back pages, parts fiche, and owners manual if you can't find the best tool you ever bought for your Yamaha, despair not, for a mere zero $0 you can download another one.
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.
1979 Yamaha DT125 cylinder torque specs Google Search
Torque Specs
Yamaha DT100A 1974 Service Manual
https://www.partsfish.com/page/oem-parts-for-yamaha
http://www.dt125.cz/download/Owners_Manual-DT125R.pdf

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Yamaha DT 125 R... | Answered on Mar 27, 2018


Hi, Adam before testing any electrical component in the Starting Circuit it is "IMPERATIVE" that you have a fully charged battery of 12.5 volts or more and be able to pass a proper "LOAD" test if necessary, you may have a preliminary reading of 12.5 volts or more but little or zero amperage, the battery is faulty and must be replaced. AGM type batteries fall into this scenario more so than lead-acid batteries.
1. Ignition Switch not in the "ON" position.
2. Engine Run Switch in the "OFF" position.
3. Engine Run Switch is "FAULTY" or corroded.
4. Check the 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.
5. Bank angle sensor needs a reset or is faulty.
6. FOB battery low or dead.
7. Faulty ignition switch.
8. Faulty starter button.
9. Faulty kickstand, clutch, neutral safety switch.
10. Security alarm needs a reset.
11. Starter relay, solenoid, starter motor or circuit wiring faulty.
12. Starter armature or field coils have failed.
13. Main fuse or circuit breaker may be blown or faulty.
14. Faulty ignition relay.
15. The electric starter is working but starter clutch has failed.
16. Check for engine trouble codes.
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.
Weird Electrical Fault Yamaha SR 125 Motorbike
Yamaha SR 125 Refusing to Start UPDATE
http://service.tanga-moteurs.ro/data/Yamaha%20SR%20125%20'97%20-%20Service%20Manual.pdf
https://www.partsfish.com/page/oem-parts-for-yamaha
YAMAHA SR125 Owner Manual

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2001 Yamaha DT... | Answered on Feb 25, 2018


Hi, Samellis before testing any electrical component in the Charging System it is "IMPERATIVE" that you have a fully charged battery of 12.5 volts or more and be able to pass a proper "LOAD" test if necessary, you may have a preliminary reading of 12.5 volts or more but little or zero amperage, the battery is faulty and must be replaced. AGM type batteries fall into this scenario more so than lead acid batteries.
1. Battery Test:
The battery needs to be a fully charged and load tested to ensure proper readings, connections need to be clean and tight. If you are not working with a fully charged and functional battery, all other voltage tests will be incorrect. Standing battery Voltage should be 12.5-13.2 DCV.
2. Charging System Voltage Test:
Start motorcycle, measure DC volts across the battery terminals you should have a reading of approximately 13.2-15 DC Volts.
3. Connections and wires:
Inspect the regulator stator plug, and check the battery terminals for connection corrosion. If everything seems to be in order, move on to number 4 below to determine if there's a failed component.
4. Stator Checks/Rotor Check: Each of the following tests isolates the Stator & Rotor. If AC output and resistance test fail and stator test passes then the rotor is at fault (Pull Primary covers and inspect rotor for damage).
5. AC Output Check:
Unplug the regulator plug from the stator start motorcycle and change Voltmeter to AC volts. Probe both stator wires with your meter lead. The motorcycle should be putting out approximately 18-20 ACV per 1,000 rpm. Reading will vary depending on system, check service manual specification
Generic Specs:
22 amp system produces about 19-26 VAC per 1,000 rpm
32 amp system produces about 16-20 VAC per 1,000 rpm
45 amp system produces about 19-26 VAC per 1,000 rpm
Stator Resistance Check:
Switch your multimeter to Ohm x 1 scale. Probe each stator wires with meter leads and check resistance on the meter.
Resistance should be in the range of 0.1-0.5 Ohms. Reading will vary depending on the system, check the service manual for specifications.
Generic Specs:
22 amp system produces about 0.2 to 0.4 ohms
32 amp system produces about 0.1 to 0.2 ohms
45 amp system produces about 0.1 to 0.2 ohms
Stator ground Check:
Switch your multimeter to Ohm x 1 scale.
Probe each stator wire with your positive lead on the multimeter and the negative to ground.
There should be no continuity to ground on either wire.
If there is continuity your stator is shorted to ground and must be replaced.
5. Regulator Test:
Each of the following tests isolates the regulator only, so if any of these tests fail, the regulator is at fault.
Identifying Wires:
Battery Charge Lead- Wire going from regulator to battery positive.
AC output leads- Wires coming from the Stator to the regulator.
Ground- Wire from Regulator to ground or regulator may be grounded via the physical bolting to chassis.
Regulator Ground Test: Ensure the regulator body is grounded or grounding wire is fastened tightly to a good ground (you should verify this by checking continuity from regulator body to chassis ground).
Fwd/Reverse Bias Test/Diode Test:
This check is testing the Diode function to ensure it is regulating the AC current for the stator into DC Current.
Switch multimeter to Diode Scale.
Place your Multimeter positive lead on each AC output wire.
Place your multimeter negative lead on the battery Charge wire.
The meter should read voltage typically around .5 volts.
Next, switch your multimeter leads putting the negative lead on the AC output wires and the Positive lead on the Battery Charge Wire. The reading should be Infinite. With your meter on the same setting, place your multimeter positive lead on the regulator ground wire or to the regulator directly, and then place your meter negative lead on the AC output leads.
The meter should read voltage typically around .5 volts.
Next, switch your multimeter leads putting the negative lead on the regulator ground and the Positive lead on the AC output wires. The reading should be Infinite.
Note: Below is a table to show the readings:
Positive Lead Negative Lead Reading
AC output 1 Battery charge lead Voltage
AC output 2 Battery Charge Lead Voltage
Battery charge lead AC output 1 ?
Battery charge lead AC output 2 ?
Ground AC output 1 Voltage
Ground AC output 2 Voltage
AC output 1 Ground ?
AC output 2 Ground ?
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.
DT125R Lighting Charging
http://racetechelectric.com/files/pdf/rte_troubleshooting_flow_chart.pdf
Yamaha DT125RE 2005 Service Manual
OEM parts for Yamaha
YAMAHA DT125R Owner Manual

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e

2001 Yamaha DT... | Answered on Jun 17, 2017


Hi, Gregorycnort for this scenario you will need your service/owners manual if you can't find the best tool you ever bought for your Yamaha, despair not, for a mere zero $0 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.
Fork Oil Quantities
1978 yamaha dt250 enduro fork oil change
Yamaha DT100A 1974 Service Manual
OEM parts for Yamaha
http://mybikemanuals.com/yamaha/yamaha-dt

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Yamaha DT 125 R... | Answered on Jun 12, 2017


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 zero $0 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.
front sprocket nut removal turn lefty loosey CBR Forum Enthusiast forums...
Removing transmission sprocket nut use torch Harley Davidson Forums
Yamaha DT125RE 2005 Service Manual
OEM parts for Yamaha
YAMAHA DT125R Owner Manual

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2000 Yamaha DT... | Answered on May 02, 2017


Hi, Anonymous sorry 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 visit the websites below. Good luck and have a nice day.
VERY IMPORTANT TWO STROKE THROTTLE CABLE ADJUST TIPS
Dirt Bike Throttle Cable Installation
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2000 Yamaha DT... | Answered on Mar 12, 2017


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 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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Yamaha Motorcycle Wiring Diagrams
Yamaha DT125RE 2005 Service Manual
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YAMAHA DT125R Owner Manual

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2000 Yamaha DT... | Answered on Mar 06, 2017


Hi, Anonymous 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 links below. Good luck and have a nice day.
http://www.thumpertalk.com/topic/824422-dt175-will-not-start
https://yamahaclub.com/forums/topic/27070-79-dt175-mistery-wont-run
Yamaha DT100A 1974 Service Manual
OEM parts for Yamaha
http://mybikemanuals.com/yamaha/yamaha-dt

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e

Yamaha DT 125 R... | Answered on Feb 01, 2017


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 zero $ 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.
https://yamahaclub.com/forums/topic/28097-yamaha-dt-125-sm-2007-starter-motor
Yamaha DT 125 RE electric starter removal
Yamaha DT125RE 2005 Service Manual
OEM parts for Yamaha
YAMAHA DT125R Owner Manual

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e


Yamaha DT 125 R... | Answered on Jan 16, 2017


Hi, Andy your oil tank may be overfilled 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.
http://www.raptorforum.com/forums/66-raptor-660-maintenance/17542-help-oil-coming-out-crank-case-breather-help.html
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YAMAHA DT125R Owner Manual
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Yamaha DT125 DT125R 1988 2002 Workshop Repair Service Manual Download...

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2000 Yamaha DT... | Answered on Jan 08, 2017

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