Spark plugs inconsistently colored

[Berkhous]

Hey guys my name is jerry I have a 94 fzr600 track bike that I just bought it has a dead spot at about 5000 to 8000 where it just drops off. I pulled the carbs apart because it was sitting in the previous owners living room for 4 years and I cleaned the carbs and put it back together and it didn't seam to help so I pulled the plugs out and the electrodes are all different colors from black to almost white. It has a d&d slip on and I don't think the carbs have been jetted looking at the grime in the float bowl. So my question is what is the color difference would it be a float issue. I'm no professional. Thanks guys