Warped Chinese Sprocket!
I was getting some parts ready for another build and decided to stick this sprocket in the lathe and check it out. Some of these Chinese sprockets are terrible. This particular one ran out over .080. It just happened to come frome Zone 8. It's no wonder people have trouble trying to true up the rear sprocket coupling. It's hopeless with a sprocket like this. Lucky I had a couple spares I had purchased from Duane at Thatsdax that ran very true. Thanks Duane!