Causes and Cures for Popping on Deceleration

QuestionThere’s a lot of discussion about popping on deceleration and I have this problem myself. What are the most common causes and cures for this problem on a fuel injected twin cam motorcycle?

AnswerNote from the crew:

Popping on deceleration is due to unburnt fuel being ignited in the exhaust. The reason you do not hear this on a bike with a stock exhaust is due to the baffling of the stock exhaust. It is not only much quieter but also does not allow the fresh air to enter the exhaust due to reversion. This fresh air makes the exhaust hotter (think of letting a fire have more oxygen) which aids in the combustion of the unburnt fuel.

To REDUCE (it may not totally go away) popping on deceleration first make sure that you do not have any intake or exhaust leaks. If all that checks out then you can alter the fuel curve at closed throttle to help this problem. If you are using a PCIII then go into the 0% column of the software and alter the fuel curve from 1750-5500rpm. The value you enter depends on your model and setup. Some Magnetti Marelli bikes responded by having a -60 put in this column while most Delphi bikes respond by inputting a +25. Also make sure that you synch the Throttle Position so that it reads 0 while the bike is idling.

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25 Responses to “Causes and Cures for Popping on Deceleration”

  1. Shirley

    F*ckin' amazing issues here. I am very happy to see your article. Thanks a lot and i'm taking a look ahead to touch you. Will you please drop me a e-mail?

  2. Paul

    Rapid City Harley said my 2012 street glide was backfiring due to a faulty voltage regulator. They installed a new one and my bike still backfires on deceleration

  3. Harley

    I own a 14 CVO RK Tour. Push rods failed on the way to Sturgis 2s. Shop said no damage. Replaced push rods with adjustables and also replaced tappest to Fueling. Had the bike dynoed before the trip, but after the parts were replaced I have occasional popping on deceleration. V&H true duals, stg 1 intake, and power commander. Thank you.

  4. edward przydzial

    i have a 2013 softail heritage and i want to stop the popcorn decel backfiring issue...

  5. Douglas Kata

    My 2015 Low Rider has a stage 4 motor kit with Bassani 2 in 1 exhaust. Bought it this way. Was told to expect the deceleration popping (kinda like it). Is that harming the engine?

  6. drew ding

    how to get harley tuned with no tuning MODULE

  7. David Belisle

    Hi , I have watched many of your videos. I have a question I have a 2017 CVO stage 3 117 cid zippers rs468 cam. I have a power vision. I had CVO cans with fullsac baffles bike run good. I just changed the muffler to ones with a 2.25 baffle there a lot more open sound deep but the bike now has a big flat spot no power from 3400 to 4000. I can roll on throttle slowly ok but still feel it but if I try to juice it in that range the bike falls flat no power all most like cuts out. I added fuel using the global selecting changing the whole map by 1 percent the other areas seem better but big whole in the middle. I continue to add fuel in the mid till 5 percent with no real improvement once I can get passed the flat spot theirs power do you have any idea's thank you.

  8. TIMOTHY

    I need information on "non" fuel injected mapping

  9. Brendan Mummart

    I have a 2012 Harley dyna with alot of decel pop. I installed a stage 1 air cleaner and the vance and hines big radius exhaust. i went with the harley now illegal super tuner. does anyone have any suggestions for what to change on my current map? I bought the software and cable kit to do it myself. not throwing money down the drain by letting harley do it. thanks

  10. Paul

    What would cause my Harley Davidson St., Bob to backfire and act like it’s going to stall them Surge