Carb Jetting really low

Mar 16, 2016
118
0
16
america
I have stock everything except an expansion chamber. The engine 2 strokes all the way down to size 64 jet. It has a good air/fuel ratio at around size 55 jet. This seems really low and even though she runs great I'm topping out at 30ish with a shift kit. How can I get more air to the engine so I can raise the jet size to get more power? From what I understand having a smaller jet results in less fuel per cycle thus less power. Thanks.