The show was about a motorbike similar to knightrider if I remember the show was early 80's american show but I can't remember what it is called can someone please help I remember it had a speed boost that counted down 3,2,1, and the bike was black.

I believe the show you are talking about was called STREET HAWK, well at least that's what it was called in scotland when I lived there.

YouTube - Street hawk vs Knight Rider the Chase (http://www.youtube.com/watch?v=yXAh8sACK2Y)

After watching Street Hawk Vs Knight Rider,
You may want to watch John Carpenter's Christine Vs Knight Rider:
YouTube - KITT vs CHRISTINE (http://www.youtube.com/watch?v=3w2QFCSy1_A)