Not an expert, but I had similar experience with my 46Fx, and it ended up killing my ultrastick One of the trainers at the field did a mini-tuneup for me after I bench ran it, and had similar results to yours, no problems. What he did is actually turn it upside down when it was running, and leaned ou the low idle screw a bit, then readjusted the needle valve. Been running great since.

Dave