i may be wrong but if your getting spark then it can't be the cdi... the cdi is what helps make the spark..basically if cdi is bad it would break the flow of electricity to the coil... now mine had a similiar problem as in started one day then next dat wouldn't.. i spent 2 days checking everythiung but never found any problems till i looked back by the grab bar and had a wire broke(split) going to the cdi box.. fixed it and fired right up...so you might check your wires and make sure they are all good mine was right behind the connecter so hard to see...also when you say you have spark and feul it should start .. when you say you have spark did you check both plugs maybe you just had spark on one side???just an idea