[blackduc238]

Broken/loose fuel line inside. Fuel line to/from fuel pump might be the issue.
I had it happen off and on with a duc I used to race. Finally gave out on the track when I pinned it. In the pits with the tank open I could hear the gurgling.
Drain, pop off the fuel pump and check the lines.
On a side note. I've not been playing with my R1100S much yet but on my R1150RTP I did the fuel filter mod so I wouldn't have to take off the tank on the filter changes. Made it way easier.