My 2001 gs500 is running rich (black / sooty tip spark plug). I have adjusted float height. What else can i do
Use hot type plug?
Adjust mixer (if yes how)?
Anything else?
Thanks for answers.

Put pods on it and I can tell ya it won't be rich. The GS is one bike that's well known to be lean and not rich. If you know how check your floats. My bet is they are off.

It just started running rich, and you didn't change anything? It could also be a weak spark which doesn't create good combustion. Check your air filter to make sure it isn't clogged too.