My kitten also has bad breath, but I'm finding it is getting less offensive as he gets older. He has lost almost all his baby teeth now I think (I found and kept 3 canines!!!) and it seems that as his new teeth come in his breath gets better.
We have breath fresheners for cats at my store....we also have bottled water with chlorophyl (spelling??) in it to freshen their breath working from the inside. It's like minty water. We have sprays you can spray in their mouthes, and we have these things called Pit'r Pats....they smell really bad but cats love them. I have NO idea how that is supposed to freshen their breath. I have never heard any feedback on any of these products.
Bad breath could also be a sign of indigestion. Is your kitty gassy at all????
I heard that kittens are known for having bad breath. Keep an eye on it though, if it's horrible horrible maybe take him to the vet...or at least ask the vet. But it might be because he's losing teeth and teething like it was for my guy.