Yes another decel pop question

Discussion in 'Dyna Models' started by LENNYB3US, May 9, 2011.

  1. LENNYB3US

    LENNYB3US Member

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    I have a 2000 dyna lowrider. I just installed the V&H Big Shot Staggereds on it. The Bike seems to run ok.I replaced the Intake gasket on the back of the carb and still the pop happens, not all the time but when I accel hard it will do it on decel, normal driving doesn't seem to make it happen. I checked the jets and I have a 48/190. It doesn't seem to have an exhaust leak. I'm really kind of stumped. Should I goto a 46 instead of the 48? PLEASE HELP
     
  2. BUBBIE

    BUBBIE Well-Known Member

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    HMMmmmmmm It sounds like a problem that THAT exhaust has... Many have complained about that same thing..... Being Not bad in your case,,,, I would live with it.. Your jetting sounds about right and I doubt worth a change for a pop or two..(lack of back pressure pop)

    Just My Way

    signed....BUBBIE
     
  3. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    You did not discuss the A/C. Has that been upgraded too?

    With the freer exhaust, you will notice a bit more sound that may not have been apparent with a more restrictive one. Still would be good to rule out an intake and exhaust leak both of which can cause decel popping. Check these out:

    Finding An Intake Leak - Harley Davidson Community

    Exhaust Leaks - Harley Davidson Community

    On the carb tuning, what you have does sound a bit large. Have you modified the engine? If not, I would go back to basics and see if you need jets that large:

    *Twin Cam CV Carb Rejet Suggestions - Harley Davidson Community

    CV Carburetor Jet Adjustment/Trouble Shooting - Harley Davidson Community

    Understanding CV Carbs - Harley Davidson Community

    TQ
     
    Last edited: May 9, 2011
  4. glider

    glider Veteran Member

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    The 48 low jet is a bit fat, you may want to try the 46 low jet and see what results you get. It could be a bit of gas in the exhaust causing the pop. Low restriction mufflers will also make the popping more noticable than stock mufflers on decel.
     
  5. LENNYB3US

    LENNYB3US Member

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    I have not modified the engine. If I go with the 46 won't that lean it out and possibly make it worse?
     
  6. glider

    glider Veteran Member

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    Typically the 46 is the one that will give you better throttle response. One way to find out.:s
     
  7. ultra...good

    ultra...good Banned

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    On my old ironhead I had the decel pop and got rid of it by putting a bigger jet in for the low range. I had to go way bigger, not just a little bit. If you want a few pdf's about jetting carbs, pm me an e-mail address and I will forward them to you.
     
  8. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Bit of a balancing act. For decel popping, you need fuel, air and spark or high heat source. Eliminate the air (leak) first. Then try a slightly smaller low speed jet (#46) and add a couple of #4 SS washers under the needle to get up in the response range quicker. I would suggest starting at 185/46. See how that does. The test in the link I gave you above is pretty good for tweaking the jets.

    Quick and easy way of testing the main jet size.

    Run the bike through the gears into third gear and run third up to 60-70 MPH full throttle, then chop the throttle about 1/8 to 1/4 back and see if the bike either surges ahead or stumbles then recovers.

    If it surges ahead, your jetting is lean
    If it stumbles and recovers , your jetting is rich
    If it makes no difference, you're pretty close.


    This will give you an idea of the adjustable jet needles and how to richen up the mixture.
    Using the stock jet needle, you shim it up with 2 - #4 washers under the head to raise it up in the slide. The stock needle does not have the grooves for adjustment.

    If the bike pulls harder at high rpm when cold and less hard when fully warmed up, the main jet is too large. Install a smaller main jet and retest until you find the main jet that pulls the hardest at high rpm when fully warmed up. This must be done first - before moving on to the other tuning ranges.

    If the bike doesn't pull well at high rpm when cold and gets only slightly better when fully warmed up, the main jet is too small.
    In order to properly tune the mid range and low rpm mixtures, THE MAIN JET MUST FIRST BE PROPERLY SELECTED after 10 to 15 minutes of hard use!
    Do not pay too much attention to the low-end richness when you are changing main jets - you still need to be using the main jets that produce the best power at high rpm. You will deal with the low-end / cruise later .

    To get the best power at full throttle , adjust the needle height, after you have already selected the best main jet.
    If the engine pulls better or is smoother at full throttle in a full throttle roll-on starting at 3k when cool but soft and/or rough when at full operating temperature, it is too rich in the mid range and the needle should be lowered.
    If the engine pulls better when fully warmed up but still not great at full throttle, try raising the needle to richen.
    If the engine pulls equally well between 4k-5+k when cooler as compared to fully warmed up, the needle height is probably properly set.


    TQ
     
  9. LENNYB3US

    LENNYB3US Member

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    A/C? Please forgive my ignorance, What are you referring to with a/c?
     
  10. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    Air cleaner

    Brian