Slight pop

Discussion in 'TFI Questions Answered By Dobeck' started by hogtyd, Jul 12, 2010.

  1. hogtyd

    hogtyd Member

    hey y'all
    I have a small annoying problem with my 07 lowrider. I have changed my pipes from stock pipes and rush slipons to v&h staggered duels. I am still running the same stage one air cleaner and the tfi. after changing the pipes I now have a small pop just as i let off the gas and pull in the clutch. It seams to be worse when outside temp is above 90 deg. I have tried leaning out my tfi and riching it up but to no avail. It does better at a richer setting than leaner, but still has that little pop. I have my pots set at 3-3:30-4-7 can anyone give me a hint as to why I can't tune this out or is this just the way it is, The bike runs great at this setting. I would just like to get rid of that pop! It didn't do this with the rush slip ons. Oh and yes I changed the gaskets when I did the pipes and they are not leaking.

    BUBBIE Well-Known Member

    On MY 09 FLHR with V&H slip-ons SE air TFI. The settings similar to yours.. BUT i don't set the last one at 7.... I use #4 setting suggested by the TFI book.. Maybe ??? This may make a difference..

    I consider the slight popping as Normal on my bike.. The "air revision" into the mufflers will tend to cause a LITTLE pop..

    This would be a good question to ASK the Dobeck people on the TFI.... Question asked here on site,,,,

    Go for it! I'll look to see their opinion if You'll ask them.

  3. Hoople

    Hoople Account Removed

    I have nothing to back up my theory but I would think for a bike to be completely and I mean completely "Pop Free", all the pieces of the puzzle would have to be perfect.

    I can see reducing it to a point of it not being a problem, but to be pop free I would think you would have to be more lucky than smart.
  4. hogtyd

    hogtyd Member

    Actually, I have already put this question to dobeck last week and as yet have not recieved an answer.
  5. glider

    glider Veteran Member

    If you set the #4 pot (high speed) to 7 on the dial, it then makes the crossover from low to the high speed circuit at 4500 RPM instead of the usual 4000 RPM when set at 4 on that pot. It also removes the extra fuel that is added by the green (low speed pot) until approximately 2000 RPM's.
  6. Hoople

    Hoople Account Removed

    There was Graph (throttle position VS rpm) that Chopper had posted a while back. It showed the different areas of the graph that was responsible for bike performance. It showed that the RPM range from 1500 to 6500 @ a Zero throttle position was the area of interest for popping problems.

    Don't know if you can cross translate that area to tfi and make the mixture different for that area only.
  7. DobeckTechSupport

    DobeckTechSupport Active Member Product Contributor

    Hey guys,

    We get numerous inquiries about backfiring (popping) on deceleration (slowing
    down). In order to have backfiring or popping on deceleration you must have three things present in the exhaust system: SPARK, FUEL, and AIR.

    A properly tuned fuel injected Harley Davidson cannot backfire (pop) on
    deceleration from redline to about 2800 RPM’s or (example:2nd gear) 30 MPH to 55 MPH. The reason is that when you shut the throttle down on deceleration the INJECTORS SHUT OFF in that RPM or MPH range which removes an essential part of the explosion. Spark, NO fuel, and air means….. no explosion. If your Harley Davidson is backfiring (popping) within that range of RPM or MPH it could be one of the following:
    1. Your bike is not fully warmed up.
    2. Malfunctioning cylinder head temperature sensor.

    If your Harley Davidson is backfiring (popping) below that RPM or MPH it could be one or all of the following most common reasons:
    1. Air being drawn in through the left hand exhaust pipe on touring models
    (aftermarket, or modified stock). Which can easily be determined by plugging off left pipe and making a test run.
    2. Leaking exhaust flange gasket or pipe connection.
    3. Intake manifold leak.

    The problem is AIR getting into the exhaust system. By adding more fuel you can see a reduction in backfiring (popping) but that isn’t fixing the problem and it usually results in drivability and/or mileage issues. It is always best to eliminate the cause (AIR) rather than changing the effect by adding more fuel.

    Hoople stated it best by saying that to be "Pop Free all the pieces of the puzzle would have to be perfect."
  8. hogtyd

    hogtyd Member

    Thanks for all the attention gentlemen, I think you have solved my problem. I changed the 4th pot back to 4(it was on 7) I an=m not sure how it got dialed to 7 because I am pretty sure I did not put it there. I had it in to the dealership about a month ago because the rpm stayed up after stopping. glider solved that problem by suggesting I clean the air hole controled by the stepper motor in the air plentum. after turning the 4th pot back to 4 it made a huge difference. the bike is almost pop free. Itnow only has a slight pop when comming off a long steady run on the highway for 20 min, or so. Thank you all for your help. ain't hdtimeline the greatist place!!!