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2017 ktm 85sx. runs fine with new plug, after warm it rides for 5 to 10 mins then backfires and stops. Have replaced fuel from 40.1 to 50.1, Plug spark is weak after this happens, any ideas

Posted by Giles Tidball on


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  • 18 Answers

Hi, most likely your cdi unit or ignition coil needs replacing.

Posted on Sep 25, 2019


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SOURCE: starts runs min. or two then stops....

Go to then click customer care, then click manuals and parts. Type in model no. and download the owners manual. This should get you the spark and flywheel gap. Probably still something in the carb. Some orifices are very hard to find and to clean but they must be clean. Also check for dirt dopper nest in the muffler.

Posted on Apr 06, 2009



  • 8 Answers

SOURCE: car runs fine for about 5 min then bogs backfires

have you had the catalytic converter checked?

Posted on May 13, 2009


  • 78 Answers

SOURCE: craftsman riding lawnmower shuts off after 15 - 20 mins.

I have a Troy-Bilt push mower that does the same.

Try this - Run the mower until the point of quitting. Keep the hood up and be ready to remove the gas cap. As soon as you feel it start to stutter like it's going to quit, unscrew the gas cap and see if it comes back to life and doesn't quit.

If that works, then what is happening is that the gas in the carburetor bowl is getting depleted faster than the tank can provide it, possibly because of a clogged vent that's supposed to allow air back into the gas tank as gas is used.

You can try running with the gas cap not quite tight, to let some air seep in that way, but that's more prone to sloshing leaks. You could also try drilling a hole in the gas cap - about 3/16" is plenty, and stuffing a piece of natural sponge in to keep the gas in and dirt out. Synthetic sponge will deteriorate in gas.

Posted on Jun 09, 2009

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Jim Parker

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SOURCE: brand new honda lawnmower starts and runs fine then backfires

There should be 1 or 2 screws on the carb. You will probably have to remove the air breather to get to the screw(s). I've been seeing a lot of these types of questions, new equipment not running properly. Factory settings were not set properly.

When you find the screw(s), screw in a clockwise direction until it stops; DON'T SCREW DOWN TIGHT, JUST UNTIL IT STOPS. Then unscrew counter clockwise 1 1/4 turns. Try starting.

Continue this process, 1/4 turn at a time up to 2 1/2 full turns. If you forget where you are at on the turning process, start over by screwing back down. Then pick up process where you left off.

If you need further assistance, just let me know.


Posted on Jun 21, 2009


  • 1 Answer

SOURCE: 2002 buell blast is running rough - missing - backfiring

Wow, my 2002 blast is doing the same thing, or at least it was untill it blew a hole through the exhaust and quit running all together. Time for a sportster.

Posted on Sep 05, 2010

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I have a 2011 KTM 250 SX-F I purchased new in December with a total of 11 hours on my engine hour meter. The problem is that after 6 to 10 laps while practicing on the track, the engine starts to...

Thank you for contacting FixYa with your inquiry.
This is a tough one but I have had similar problems with other bikes usually an upgrade for a chip in the ignition systems computer or black box.
In this case it sounds like the stator winding's. When it's cool all is well in runs normal. When heat transfers to the stator (Basically an Electric Motor with Winding's around it's poles) it expands and the winding's could be separating and/or shorting out. You could test the leads with a good ohmmeter (meg ohms) after your runs and see if there is a different reading then from when it's cold. see figure #3 3 77139004000 STATOR $184.99 $184.99

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Have a 2005 ktm 525 exc,after 20 mins of riding it starts missing and stalls when slowing down for gate or log ect,when i try to start it takes a bit and will pop or backfire through exhaust, had jd kit...

sounds rich, especially if its a problem when it warms up, was the JD kit a much bigger main jet,might need to try standard main, is it standard exhaust, I assume the air cleaner is clean and good condition, the foam can deteriate over time.Not sure if you have a hot start button or lever, this leans the mixture, if you have one and it helps then its definately rich

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Car runs fine for about 5 min then bogs backfires

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