Here's a photo of my moped and my carb. I'm willing to spend whatever is needed. I've read everything everyone has wrote and I think I'm going to start by turning my current carb and if I need to, put an aftermarket intake on. After doing that if I don't see any improvements I will look into getting a 17.5mm. I'm not putting the old piston and cylinder back on because I'm pretty sure the piston is broken and the cylinders are very dirty and very used.
Also about the air filter you linked. that tyoe of air filer would not fit nicely on my moped because my current stock air filer in long and rectangle and it fits nice under the side plate. the circle air filter would not fit under the side plating.