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Thread: Backfire when decelerating?

  1. #1
    Join Date
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    Backfire when decelerating?

    I have a 1985 Honda BR 250es. When decelerating in gear I am getting "popping" out the exhaust, and very occaisonally a larger backfire when in gear with no throttle, such as idling down a steep grade. Any common reasons for this? Fixes?
    1985 Honda Big Red 250ES
    27x12-10 Mud Bug rear tires on ITP aluminum rims
    27x10-12 Mudlite on front
    *****************************************

  2. #2
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    adjust your mixture screw
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  3. #3
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    Incorrect fuel/air mixture. Sounds like its running a little rich.
    You will have to play with your carb and see if you can fine tune it a little.
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  4. #4
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    Also, you might have a slight exhaust leak that will tend to draw in fresh air into the exhaust when decelerating and will cause this problem. Had it happen to mine once.

  5. #5
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    Quote Originally Posted by ATCwithdrawals View Post
    Also, you might have a slight exhaust leak that will tend to draw in fresh air into the exhaust when decelerating and will cause this problem. Had it happen to mine once.
    How far back in the exhaust system would this be a problem? I don't have a factory muffler on it, and I may have a slight leak where it is connected because it is not an OEM size pipe, but I didn't think that would casue a problem if the leak is that far back.?
    1985 Honda Big Red 250ES
    27x12-10 Mud Bug rear tires on ITP aluminum rims
    27x10-12 Mudlite on front
    *****************************************

  6. #6
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    Quote Originally Posted by Rustytinhorn View Post
    Incorrect fuel/air mixture. Sounds like its running a little rich.
    You will have to play with your carb and see if you can fine tune it a little.
    Are there any instructions on doing this anywhere? I can only find base instructions for the pilot screw, but no other instructions in my repair manual or owners manual.
    1985 Honda Big Red 250ES
    27x12-10 Mud Bug rear tires on ITP aluminum rims
    27x10-12 Mudlite on front
    *****************************************

  7. #7
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    Quote Originally Posted by ATCwithdrawals View Post
    Also, you might have a slight exhaust leak that will tend to draw in fresh air into the exhaust when decelerating and will cause this problem. Had it happen to mine once.
    I would have to agree.
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  8. #8
    stoney420's Avatar
    stoney420 is offline At The Back Of The Pack Arm chair racerAt the back of the pack
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    this should give u a pretty good understanding of carbs..
    http://www.3wheelerworldforums.com/s...ad.php?t=55086

  9. #9
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    Quote Originally Posted by 01ps View Post
    Are there any instructions on doing this anywhere? I can only find base instructions for the pilot screw, but no other instructions in my repair manual or owners manual.
    Quote Originally Posted by stoney420 View Post
    this should give u a pretty good understanding of carbs..
    http://www.3wheelerworldforums.com/s...ad.php?t=55086
    Thanks Stoney.
    A few wheelers, + an
    '73 Honda 49cc Mini Trail
    '85 200 Big WHEEL

    "Despite the cost of living, its still popular."

  10. #10
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    Quote Originally Posted by ATCwithdrawals View Post
    Also, you might have a slight exhaust leak that will tend to draw in fresh air into the exhaust when decelerating and will cause this problem. Had it happen to mine once.
    I did find a leak right at the joint near the kickstart, havn't fixed it yet, but it was a fairly large leak that was not loud (compared to the muffler), so I didn't notice it till I blocked off the muffler.
    1985 Honda Big Red 250ES
    27x12-10 Mud Bug rear tires on ITP aluminum rims
    27x10-12 Mudlite on front
    *****************************************

  11. #11
    Join Date
    Oct 2003
    Location
    Maine
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    My freind put a aftermarket on his BR and had a leak in the same spot as yours and after we repaired the leak it never backfired again, so I'm almost positive that when you repair this leak you will stop the backfiring..
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