Im gonna say FPR, but like dave said check the dumbest thing possible 1st choke. (we've all done it man or we wouldn't know)
Not to familiar with the inards of the 929 but do a google search on "Fuel pressure regulator test cbr 929" it's easy and free to test if you read up on it and easy to replace. I bet thats it, or do you have a Power commander or something like it? If so disconnect it and plug the wiring harness back together like honda had it. Ive seen those go spooky on several bikes.
Mabye someone more familiar with the 929 with chime in, I wonder if a simple vacuume leak would do this???