speedfight?

adam bike doctor i have a speedfight 2 ive had a lot of problems with it starting this is what ive done so far ive changed the head and pistons as they needed changing anyway ive checked the oil pump to make sure theres oil getting through and there is ive had new jets put in checked the wireing it will start but it takes ages and i mean ages ive been told its the cdi unit or box what ever you call it as ive tried everything else to see why it dosnt start all the basics i can think of and nothings worked you are my lkast hope