I bought this bike in December, it looks great, runs great and everything works. Except yesterday I started it with the choke on and after a few seconds the tach dropped to zero. While riding I noticed that it wasn't running right as if not all cylinders were firing or the fuel was bad. Once in a while the tach came on and the bike ran good. I stopped, added fuel and started it up. All seemed fine until a few yards and the same thing happened. I took it to a dealer.............who is having a field day with it. I've been riding this bike 60 or so miles a day without any problems. Any thoughts?