Is there any way to beef up my 300ex starter so it wont have trouble starting my bike ??
I put a more compresion piston in it, and it could barely turn it over.

 

If you know a good engine builder, or contact CTRacing, FST, Denton, etc., & see if there is a way to adapt a compression release from another machine to your ride. Many quads with backup recoil starters employ compression releases to allow one to use the recoil starter when necessary.