Strange Vibration

[His Dudeness]

Did this problem only start after you worked on the carb or was it there before? Between fully open and fully closed what throttle position are you having the problem? From what I picked up the problem is at low throttle input and things get better as you open the throttle wider. Is that right? That would suggest to me a problem with pilot jets, mixture screws. At small throttle inputs they make a large contribution but as you open the throttle they have less influence and the main jet and needle contributes more so if it's a problem at small throttle input I'd guess blocked pilot jets, mixture screws not right. A quick test you could do that would help confirm that would be to richen the mixture by giving the bike a bit of choke and see if that improves the problem. If it does then you have a weak mixture. Another trick to help pinpoint the problem is to throw water on your headers after a test ride and check to see if they dry at the different rates. A lean cylinder will be hotter so should dry quicker than the others. Your mixture screws should be close to the factory spec they shouldn't need much adjustment if the do then something is wrong.

There's a graph of throttle position vs what part of the carb is having an effect http://www.ducatitech.com/2v/img/fcr_graphs.gif