Hi I have a 02 500 HO and this staring problem has been coming and going and now it has decied to stay. It cranks and cranks then lets out a huge backfire. I have good spark good compression. I then shot some starting fluid down the carb and it shot a fire ball out the exhaust. I belive it is a timing issue. When I contined to trouble shoot the bat. went dead. I put a charger on it and it started and ran fine. I let charge all night removed the charger wont start put it back on started took it off and wouldn't start again. I put it back on and started. once its warm starts every time. I checked the batter voltage and its 13.0 volts. What could be my problem I am beating my head on the wall.