650 V2 firing problem

Alright guys I could use a little help I have an arctic cat 650 V2 an so far its been a money pit. Just put $1200 in to get bottom end rebuilt. Mechanic finished motor and put it back on bike. trys to start it and no fire. Bought a new ignition(dynatek) now it sparks for maybe 2 seconds and nothing else. put on new stator, coils, and flywheel. still only firing at first push.:banghead: If anyone has any idea as to what maybe going on I could really use the help!!!!!!!