Question about Yamaha DT 125 R Motorcycles
Had a fault with the cdi unit so have managed to source and change the unit. The bike now runs smoother. However at higher revs the bike cuts and stalls. As soon as the bike stops you can kick it over and start teh engine without a problem, but once it has been running for half a mile or so it cuts out again
Posted by Anonymous on
Hi, Anonymous the following applies to carbureted also fuel injected models and the usual suspects are:
1. Severely discharged or a damaged battery, 9 volts or lower.
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. Water or dirt in the fuel system, carburetor or filter.
11. Restricted, blocked or kinked fuel line.
12. Fuel tank empty.
13. Gas cap is not venting properly or fuel tank venting system blocked.
14. A failed fuel pump, pressure regulator and or fuel injectors.
15. Vacuum line from intake manifold to petcock broken, cracked, or not attached, carburetor vent line plugged.
16. Needle and seat stuck closed in the float bowl.
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OEM parts for Yamaha
Posted on Mar 11, 2016
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Posted on Jan 02, 2017
Sounds like you have a fuel delivery problem. First check to see if there is a inline filter from the fuel tank to the carburators that is partially plugged. If not, you will have to remove the fuel valve from the fuel tank and clean the screens on the fuel pick-up tubes. The only other thing that would cause a fuel delivery problem would be the vacuum line from the carburators to the fuel valve has a split causing insufficient vacuum to open the fuel valve.
Posted on Nov 16, 2009
Hi there, you likely still have the restrictor in the exhaust header. Mine was the same, they are shipped like that as standard. Take the exhaust off the engine and remove the the concentric tube that's in there (you need to cut it out). Instant +100% power, if that is your problem.
Posted on Mar 05, 2012
SOURCE: bike running rough at lower revs
If the bike sat without being used over the winter It could be bad gas. if gas sits without being used for an extended period of time it destabilizes and gums up carborators and fuel injectors, you need to add a fuel stabilizer to gas when storing for winter. To fix the problem the gas has to be drained from tank, then refil with fresh gas and appropriate amount of carborator/fuel injector cleaner/treatment. Then start the bike and let it run it should clean itself out and start running smooth. If bike did not sit unused for winter its possible they installed the wrong plugs sometimes they talk you into spending more money on platinum or split fire/gimmick plugs (always use the exact same plug that came in the bike when it was new!!!!!)
Posted on Mar 17, 2012
fuel air is my first thoughts
Posted on Oct 30, 2012
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