Moped Army

First thing i would do would be to mess with your exhaust. Either re do your silencer or buy a performance pipe. Stock pipes have too mutch back preasure, you can get another 20% or more out of an engine by changing the pipe. I would also mess with the tunning mixture, perhaps air screw, jetting, and neadle adjustment, and I would try to reduce any resistance in the air filter assembly, if it means putting on a different filter. BTW you can buy sweet cold air intake filters for Brigs and stratons at a local hardware store. There about 5 or 6 bucks. I personally really like them.