I'm having the same problem with my k7 750, when you dump the clutch in 2nd gear, there is something keeping it down, I've tired it around 35 mph, I've tried it riding at 7k rpm and dumped the clutch at 14k rpm and it won't come up, it loses power and comes back down, I was wondering if it was because I just didn't know how to do it, but I let a guy at one of the local shops ride it that's been doing wheelies and working on bikes for years, and even he can't get it to come up standing on the back pegs, so any help with this would be appreciated.
It's because you're in second gear at 35MPH, that bike will wheelie like the day is long. You jut gotta figure it out. I'll agree the gixxers are a little tougher to wheelie with stock gearing but in 2nd gear your gonna need to have it pined at 35 MPH to do anything. First gear is a different story and no you don't need to change your gearing you just need to change your approach.
06 GSX-R 1000
06 GSX-R 600