I've been trying to get my old bike running, but I'm not getting spark on the left cylinder. Its getting a nice spark on the right cylinder, but the left cylinder just sparks once when you hit the start button and once when you let off. I tried replacing the coil, but the new one acted the same. I checked the wiring connections and everything looked ok. Could this be in the ignition control box or is there somewhere else I should look? Thanks for your help.