I don't want to pull the carbs off (again) but my engine doesn't idle good and if I pull off #3 and 4 plug wires it don't change anything, pull off # 1 or 2 it will die. at faster rpm all pistons are firing but it still don't run good at that. I just put the engine back in and also cleaned the carbs. the bike ran great before I pulled the engine. what would effect only the back two cylinders? a weak coil?