I saw some of this movie on tv a long time ago but I don't know what it's called. What I remember of it is that there was a guy on a motorcycle and A girl in a mustang (I think a convertable) cuts him off or something. Then he runs off the road and falls off the bike. Then he gets the bike running again and catches up with her. He rides along side the mustang and kicks in the door as he rides by. Then somehow she has a flat or something and she rides with him. They stop to work at a brickyard in one part and then later he bets her earings or maybe a ring of hers in a hillclimb he enters with the bike. I have no idea what this movie is called or who is in it. I'm pretty sure it's an older movie, maybe in the 70's. I tried searching google for stuff i could remember from the movie but it keeps coming up with stupid unrelated bull that I don't care about.

Then Came Bronson

It was actually a TV show, but they made the pilot episode (which is what you're describing) into a movie.

Tarantino was a huge fan of it, and had the motorcycle guy (Michael Parks) in like 3 or 4 of his movies. He's the sheriff in Kill Bill who's talking about the wedding massacre, etc.

The whole thing is on youtube:
http://www.youtube.com/watch?v=4ebZsLrG3lQ

Not the version with the topless scene though