I picked up a used yz450f yesterday. The bike was a JGR factory bike. Started first kick when I tested it. Seemed like a quality bike. Got home late so I didn't try starting it. This morning I tried started it for the first time and it started first kick. I was letting it idle and warm. It ran for about 45 seconds and then shut off. It wouldn't start again. Almost like when a carbureted bike has the gas turned off. I've been kicking and trying different things all day. My foot is bruised from kicking so much... anyone else have a problem like this? I replaced the fuel and made sure there was a spark. I'm following the proper start procedures. It won't even bump start. Any help is appreciated.