Right off idle it should pull pretty cleanly. Theres not alot of power right there, but it should not stumble. I went to a 42 pilot with a 155 main, and with 1.5 turns out on the airscrew i had a stumble right off idle. I held the throttle right on the stumble thinking lean bog, and then looked at the plug. It turned out to be rich. At 2 turns out on the airscrew, whap, it runs like a scalded dog right off idle.
I'd say warm your bike up, put it in 3rd gear, crack the throttle open just a tad and run it for a minute. Cut it and look at the plug. I bet your a bit rich down there.
This is with a fmf gnarly (torque) pipe, stock silencer, mix is 32:1, airbox lid is drilled a little, 500ft, 65F.