Need Help with Decel pop on dyno tune

Discussion in 'Engine, Fuel and Exhaust' started by NewtoHD, Sep 18, 2011.

  1. NewtoHD

    NewtoHD Member

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    Had my bike dyno'ed at the dealer with a SEPST, I am getting decel pop at 1500 and 2500 RPM. Took it back to dealer, they stated everything looks fine and some pop is normal, it is enough to be annoying. It also pops when shifting from 1st to 2nd or if I rev it up pass 2500 RPMs in neutral. If someone with experience with the SEPST could tell me what changes I could make to the tune, I would really appreciate it.

    Thanks,

    2011 Limited, 103 with SE AC, Rush exhausts.
     
  2. Hoople

    Hoople Account Removed

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    Before you make any adjustments, you have to know for sure there are no exhaust leaks. The Rush exhaust pipes come attached to each and must be installed as a "pair" correct?
    If so that could be a problem.

    I was truly AMAZED at how small of an exhaust leak would cause popping.
     
  3. NewtoHD

    NewtoHD Member

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    I have looked all over and have not found a leak yet. I have V&H power duals headpipe and the Rush is slip on exhaust. I have tried several techniques that members have suggested to find leaks. Short of taking the pipes off and reinstalling with new gaskets, I am not sure what to do.
     
  4. glider

    glider Veteran Member

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    To locate any leaks you may have at the joints in the exhaust or at the mufflers, try starting the bike and with some heavy gloves on, block the exhaust at the outlets and listen for a hissing. You can locate any leaks this way.
    It may be better if you have a helper listen for the hissing while you block the exit of the exhaust from the mufflers.
     
  5. Hoople

    Hoople Account Removed

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    What was the sequence of events that took place. I take it you purchased the bike New and the factory setup had no popping. Did you install the entire exhaust system yourself and all at one time. Then you took it to a dealership and had them hook you up with a SEST? Or did the dealership do header pipes/slip-on's & SEST.

    Are the V&H header pipes independent or attached/welded to one another. Would you know if new wire mesh gaskets were used when the header pipes were installed.

    You can try adjusting it out using the SEST. Do you have the software, cables and can navigate within the program. Knowing how to perform a VCI recording while riding the bike would be almost a must.

    Which popping do you experience more,, and to what degree.
    Example #1: Your in third gear. You accelerate under full throttle to 5000 RPM and you CHOP the throttle WITHOUT PULLING IN THE CLUTCH LEVER or shifting. Your using the engine as a brake. Do you hear popping?

    Example #2: Your in third gear. You accelerate under full throttle to 5000 RPM and you CHOP the throttle and at the same time you pull in and hold the clutch lever without shifting. Do you hear popping.
     
  6. kstrohs57

    kstrohs57 Active Member

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    Hey did you ever get your decel pop fixed ? It took me (3)times @ my local dealer to get proper tune on my 2004 ultra with 103 & race tuner. It backfired like shotgun during decel & i had no exhaust leaks , it was the air /fuel mix on the tune .
     
  7. Nuke99

    Nuke99 Member

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    You might not want to go this route, but I had the same problem on a 103. Dyno'd fine. I added a Power Commancer and added fuel at zero throttle 1750 rpm and above (as recommended by Fuel Moto). Almost all popping is gone. Sometime just a low rumble, but no loud popping. If no leaks, then it is just running lean.
     
  8. NewtoHD

    NewtoHD Member

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    Hoople,
    I bought the bike new 6 weeks ago, no problems stock, at the 1000 mile service had the dealer install SE AC, V&H headpipe (one piece from cylinders to the crossover) and Rush exhausts, then dyno it with the SEPST. I left the shop with popping upshifting from 1st to 2nd, 2nd to 3rd. Decel pop on thottle release in the 1750 range. Will also pop if I rev it up past 2500 in neutral. I have taken it back twice to the dealer, they keep it for a few days and say everything looks fine and that I should expect poping since I have more open exhaust that stock. I have tuned several changes in the decel enleanement but may have not been bold enough with the changes. I have also bumped the VEs at idle by 10 but nothing seemed to fix it yet. Plan to try bolder changes in the near future but just spoke with indy tuner who thought my AFR and VE are not anywhere close to being matched which may be the reason for my poor performance and the poping. Sounds like I wasted big bucks for a dealer dyno, I would have been better off with a canned map from the SEPST software.
     
  9. Hoople

    Hoople Account Removed

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    Your Indy may be 100% right but this is my take on your popping...

    I found it very difficult to install the header pipes "as a pair", keeping them aligned to the cylinder heads and support brackets,,, allowing EACH to seek their own position,, tightening down the flanges and having no leaks. That's a tall order. It's easy to do with independent drag pipes but as a welded pair I found it tricky. I took my time with new header gaskets and would have bet a grand I had no leaks but I did have a rear cylinder leak on the first & second go around. They were small leaks but they were there and I had popping.

    I was able to borrow a friends EVAP smoke machine (used to find leaks on automotive EVAP systems) and nailed the leak in minutes. I also used Walker high temp acoustic sealant on the wire mesh gaskets and slip on's. Yes, it makes it hard to remove them if you need to but I did not care. I wanted absolutely no leaks from the piston to the exhaust tip.

    Before you jump into the maps, you may want to check around at a few local automotive repair centers to see if one of them has a smoke machine. Just jack the bike up and remove both spark plugs. Using a plastic straw, place the cylinder you want to check on the exhaust stroke. Pump the smoke into the spark plug hole (not the exhaust pipe) until the smoke comes out the pipes. Now jam a rag in the exhaust slip on's. You will locate the smallest leak in seconds.

    It took 3 attempts to finally get it completely sealed for me. I am glad that I did not jump into the maps in order to correct it. It just would have compounded the problem.

    If you do "smoke it",, I would like to know what you find. I put $10 on you having a leak,,especially since your header pipes are joined together and must be installed as one..
     
  10. Grillfish

    Grillfish Junior Member

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    Some ideas on what I changed for the same situation.

    1) Save the map that they installed on your laptop. you paid good money for it and you do not want to loose it.

    2) Copy that map with a new name then....

    3) assuming your VE tables are calibrated properly (and they should have after the dyno) drop your AFR table in the 20 MAP collum (farthest left) from 4K down to 1250K. I dropped mine down to 13.8. This should help the decel pop when you have the throttle closed (not turning it) and the engine is braking.

    4) go into your decel eleanment table (this adjusts the volume of fuel when closing the throttle (i.e. when you shift) and either increase it (reduces the fuel when closing) or drop it (increases fuel when closing). I decreased mine slowly until it stopped.

    5) What is your AFR map look like? I've noticed if your idleing at 14.6, and you take off, the exhaust is so hot it ignites in 1 to 2nd gear shift (pops). I'm only running closed loop for my cruise range (1250 to 3000 from 30-70 MAP). Still getting solid 42 mpg.

    6) I also changed timing to what the canned map was from the SEPST program and that helped, but the dyno guy should have adjusted timing as well as all other aspects of the map when your bike was dynoed.

    Hope this helps...