I got a used crank under drive pulley, and it looks like it has been powder coated.

Not sure if it came like that new or if it was done by someone. It isn't the best finish, has some flaws in it.

Could this add weight to it, and throw it off balance? I think it will be fine, but thought I'd ask.

 

I can't imagine that it would cause any problems. There are bigger things rotating around on the car with imperfections and they don't cause problems. Got any pictures of what you are talking about though?

 

Once bitten!twice shy!