up to a while ago i had a perfect moped. then it started to foul the plug so i bought the same one. then i ran it for 2 weeks and one day i got to start it up and no start. i check gas. ok and then compersion...ok....then spark and it gets spark. weak but its a spark. so i start to pedal backwards with my hands like hell and all i get it a couple of back fires and smoke. could it be the electronic ignition or the step up coil or the magneto coil? help plz.