Magician Running Funny

[_skid87]

I had about 60 miles on the bike tonight and decided to ride it into town, about 8 miles one way. About half way there I notice it running a little funny. Best I can describe it is a surge. Riding at a constant speed it would randomly bog a little for a second every few seconds. I was WOT. All I have done to the carb is adjust the mixture screw out to 2 turns and shimmed with a couple washers. I figured it was close to right as I can hit 65+mph on flat ground and sometimes 70 downhill. Suggestions? Have not checked valve clearance yet and know I need to. It's still cold blooded but not hard to start when hot....