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Thread: 4 wheeler tune up

  1. #1
    Join Date
    Jan 2010

    Default 4 wheeler tune up

    i have an off brand 4 wheeler that backfires when riding. it is a mastiff bashan 125 cc. looking for information for tune up to prevent backfiring..

  2. #2
    Join Date
    Jan 2007


    Hi quadpayne,

    Unfortunately we don't have a manual for your quad. Does the backfiring happen on deceleration? If so, look for leaks in the intake manifold, and make sure your valves are adjusted within spec (I don't know what the spec is, but sometimes that information is included on a sticker somewhere on the quad). If the engine is equipped with a secondary air supply emission control system, sometimes called a "pulse air" (or PAIR) system, that could be causing the backfiring. If that's the case, there's not much you can do about it (except blocking off the system, but you're not supposed to do that).

    You might try checking www.repairmanual.com to see if they have any service information that would work.

    Good luck.

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