I had a problem with my 06 America after installing a set ot Staintunes, re jetting to 135 mains and replacing the air screws to the after market ones from Brent. My choke quit working completely, the bike would "stumble" at wot and was very hard to start. I went back to 130 mains that I had in with the replaced set of D & D's and continued to have the same problem. I then replaced the 130's again with the 135's and removed the after market thumb screws and noticed that the "new" thumb screws seemed to have some sort of coating on them. I used some low pressure compressed air to blow out the holes where the air screws go and replaced the after market screws with the stock ones and it cleared up the problem. It seems that when I seated the "new" thumb screws to get to a start point for setting the number of turns out that something "rubbed off" of the new screws and clogged up the passages inside of the carb. After installing the original screws the bike runs great. I did notice that after installling the new thumb screws that the tips and the threads did look a bit more of a "brass color" whereas the rest of the new screw had a more "orange " color...like something was rubbed off from installing them. Anyway the bike runs great now and I only assume that the new screws were the problem.
