Not sure about with synthetic oil, but all the two strokes I have ever run, blow blue grey smoke when too rich. I have never seen anything even approaching black.
I think he's talking about the small exhaust exit at the end of his muffler. The little stub pipe that is about 1/2" in diameter and is welded to the end cap. To answer his question based on that assumption; no that would leave your exhaust wide open and would effect your power and make your bike more than a little annoying to you and everyone within a block or two. We need to know if your "red hot" statement was figurative or literal.
Tom