Ralph,
I have the same issue with my 06 TBA all you have to do is loosen the gas cap up and it will take care of the problem.
There is a vaccumm tube that runs down the frame and hangs down by the rear wheel there is a small check valve in the line that prevents water from getting sucked back up the tube. Locate the tube and put a 45% cut at the end of the hose it is squared off now and the problem will go away.
If your riding in the rain and it starts to quit just loosen up the gas cap and she will clear right up and keep going.
