Well I have had my 05 R50 for a little over a month now. Everything seems to be working well.... However I sometimes notice a faint rhythmic clicking sound in the rear of the car when the car is quiet ( no radio). I notice it when I first start up or when at a stop light. It sounds very much like the clicking sound of emergency hazards. Any thoughts?
There is a pump in the left rear for the vapor recovery system called a Leak diagnosis pump. It is possible that might be the source of the sound as well. Diagram found here RealOEM.com  BMW R50 Cooper Activated Charcoal Filter/mounting parts