Ok I have only had my bike for three or so weeks. When I first bought it the engine ran real smooth. Then after about a week I could kinda start hearing a sound like it was missing, but only when it was cold. Now I can hear it when its idle or when I am at a constant throttle. If I am accelerating I can't hear it and it sounds smooth again. So I'm thinking it was the plugs. THe guy I bought it from said he just put plugs(iridium) in the bike about a month before I bought it. I pulled them anyway, and they still look good. Now I'm thinkin its a fuel issue, but I'm not sure. What could it be?