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  1. #1

    Default Butterflies and Throttle Hesitation

    Hi guys..

    My 2006 FZ1 now has Graves stacks, CopperDawgs flies and Hindle exhaust, with emissions stuff blocked off.

    The mods helped. My dyno tuner got another 15 hp out of the bike.

    That said, the bike now has a new throttle hesitation. Rolling the throttle from closed back to open, however gentle, results in a cough or sometimes a backfire.

    The bike did this when I got it, before the mods, but my tuner did the standard ECU fix at that point, which completely eliminated it.

    Another tuning session yesterday, in which my guy tried to adjust the timing of butterflies opening, to remedy the new hesitation, just made it worse. We reverted to his original tune and kind of gave up.

    One thing I noticed throughout. While doing the first dyno session following the mods, I saw that, at idle, the flies were horizontal, or fully closed. At full throttle they only opened to the 3/4 point, never fully. I dialed the range adjuster to make it so the flies would open 100% at full throttle. That made it so they wouldn't close all the way, but stayed open about 1/4 of the way at idle. This gave the best hp numbers so I stayed with it.

    Now the cough. I tried readjusting the flies back, so they'd close at idle and only open 3/4 at full revs, but the cough stayed the same.

    My dyno guy thinks the shape of the CopperDawg flies, with the extra air flow, is causing the cough. I'm not sure [I]what[I] I think.

    I could try putting the stock flies back in to see what happens. It's also possible the butterfly actuating mechanism itself is faulty.

    Is it normal for flies not to move in a full range, from closed to open?

    WTF a bit at this point. I don't see a single question or complaint on this site about CopperDawg flies.

    Any ideas..?

    Thanks - - - Mark

  2. #2


    Put stock flies back on, should fix the issue, it's letting air past when it's not supposed to. Most ecu flash tuning I've seen shows stock flies work best.

  3. #3


    Hi folks..

    Got hold of Ivan at Ivan's Performance Products. Sent my ECU to him, got it back within a week, installed a Power Commander and followed his instructions.

    Ivan was helpful over the phone and we got the setup dialled in.

    Problem solved. Throttle hesitation is gone, and power has increased across the rev range.

    Smooth and fast. Great investment..




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