Flat Spot / Throttle

Discussion in 'Engine, Fuel and Exhaust' started by M/C Dave, Apr 18, 2012.

  1. M/C Dave

    M/C Dave New Member

    I have a 2009 Harley Ultra Classic, stage 1 kit with Screaming Eagle Super Tuner and Bassani 2 into 1 exhaust. (the bike has a fly by wire throttle.)
    The problem is that there is a very noticeable and annoying flat spot in the throttle under 2000 rpm.
    The local dealership's service manager said there wasn't anything that he couldn't straighten out on the dyno.
    He was wrong... when I got it back it seemed to have actually gotten worse and the service manager said that it was because the Bassani is too high performance and isn't creating enough back pressure.
    I have also heard from another HD mechanic that it's the fly by wire set up, it's a common complaint due to the throttle positioning sensor and can only be corrected by using an add-on part that Kuryakin sells.
    Can you offer any insight?
  2. 89stroker

    89stroker Active Member

    Have you had this bike since new or did you just purchase? I thought I noticed this when I first bought my 2010, but have long since forgotten about it, as I don't ride the bike below 2000RPM very much, that would be lugging it.
    Vance and Hines sells whats called a throttlepak, supposed to take all the throttle lag out of the fly by wire bikes, check it out, just go to their website to have a look.
  3. Hoople

    Hoople Account Removed

    Really need to know what a "flat-spot" means to you. I have cable pull throttle, so I have no clue what TBW feels like.

    Is it similar to a bog where it feels like the engine wants to die, then it grabs and takes off?
    Does it only happen when you suddenly increase the grip position?
    If you were to gently increase the throttle, is the flat spot gone. The bike just gently pulls harder?
    Is it less noticeable when the engine is cold. And I mean cold like in under 90 seconds of running time?
    Is it only an "off idle" flatspot. If your cruising along at 3K RPM and nail the throttle, does the engine go flat for a second or does the bike just start pulling.

    There are values & Maps in the ECM that deal with some of the above issues.
    There are no historical codes stored? A WOW test shows there are none.