Hi, i am after some help on my rzv500r that i have not started for three years, i've put a new battery on the bike and cleaned all the carbureters out i have a spark on all four cylenders and fuel to all four carbs but it only runs on two cylenders, the frount two. but when i spray fuel in the inlet of the two carbs that it dosent run on it runs, please can some one help me. thanks nigel.