ORIGINAL: gaRCfield
Isn't it possible that he's not getting enough tank pressure with the pitts muffler? I've heard that can happen, and other than his needle position I don't see a good indicator of the engine set rich or lean.
I would try the stock muffler just to see if anything changes. If the muffler is the cause, try plugging one of the exhaust ports on the pitts muffler to increase exhaust pressure to the fuel tank.
Just my thoughts...
Joe, the first clue to the OPs problem was 2 1/2 turns out. Just for grins turn in the needle on one of your running two strokes and I will bet money you are close to 1 1/2 turns out on yours, that is about the normal place on an engine. 2 1/2 turns is just where the factory says to start the engine to make sure it never goes lean on you, not even close to where they run at.
I have never had a Pitts muffler that didn't give enough pressure but I hear of it happening once in a while. I use Bison Pitts myself and they have a baffel system and produce pressure just like a stock muffler. Some of the older mufflers were just cans with two pipes and the pipes were too big, I don't hear of the problem much any more but I'm sure it still happens.
New bike?? What did you get??
Gene