I started this thread last year and thought I would give a final update. I have had the bike out a lot in the last month and enjoying exploring its performance. The noise is still there but I am convinced it is a fluttering of the butterfly vale / valves on the intake. It happens in any gear about 2 cm of throttle on and then clears with more throttle. I had seen this referenced in other postings and even some solutions about rotating the throttle body but I don't want to start tinkering. I am just leaving it as it is and enjoying the bike.