could be a lot of different things and most brought on by the gas we are stuck with. usually end up taking carb apart and cleaning with carb cleaner. sometimes it will be the fuel line but since it will crank it is more likely the carb has lacquered up. once you get it running put a little seafoam in your gas can to treat whole thing while you work.
mr Butler did a good job on my seat and repaired a broken bolt for me while he had it. give him shout and see if he can fix you up and by the way I rode mine for two years with one bolt broken.
I believe Tony was watching the car in front of him and never seen the driver until it was to late if he seen him at all just wasn't looking for a person to be on the track.
X-2 on the cell phone advice, we are constantly telling my Mom & Dad and my wife's Mom and Dad to keep their phones with them. glad your doing good if you need something just hollor or use the phone.