KTM 525 XC Backfires
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  1. #1
    Junior Member Rookie
    Join Date
    Jan 2017

    KTM 525 XC Backfires

    I have an 2008 KTM 525 XC. Its an awesome ATV, but if there is one thing I would change it would be to eliminate backfiring. Under heavy acceleration, when I let off the gas it backfires every time and its annoying.

    A guy at work told me I probably need a jet kit and told me to check out JDJetting.com. I contacted them and they said instead of a jet kit, I probably just have a slightly plugged pilot jet so I should try that first.

    Does anyone have any experience with this backfiring and how they corrected it?

    Thanks all for your help.

  2. #2
    Senior Member Member
    Join Date
    Mar 2011
    Bickleton ,Wa
    These quads are notorious for backfiring. It is mostly caused by sucking in cold air on decel between the header and exhaust flange on the cylinder. Some people have welded the flange and header pipe together, some have trimmed the edge of the header pipe to make it fit tighter on the flange.
    08 525xc ≡ 12.5:1 570 bbk, +1 valves, Crower Cam, Houser Bounce Nerfs, Razr 2 rears, Razr fronts, Pro Armor Dominator Bumper, Scotts Steering Damper, Mino Water Pump, FCI intake, KTMBill Skid Plate, FastRanchero 41mm Carb

  3. #3
    Senior Member KTMATVHQ Member
    Join Date
    Nov 2015
    What throttle Jockey said, it isn’t really causing harm. If it bothers you enough I believe the updated part number is SXS02540506 that fixes it or you can carefully take off small amounts of the inlets on the header. I think someone said 1/8th of an inch needs to come off.

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  5. #4
    Junior Member Rookie
    Join Date
    Jan 2020
    Your head tube is likely to leak at the flange of the head. Very common on RFS engines. You will need to trim off the front of the pipe about 1/8 inch. Usually sealed after that.


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