Moped Army

so i picked up a 77 motobecane last week with the av7 motor. i put on a 30mph cylinder and piston with some porting to match what the guide said in the wiki. it has a dellorto 15mm carb with a 68 jet. that seems a little high to me but the plug is running a nice coffee brown color.

the bike will do around 32 on the flat ground. not nearly fast enough to keep up with my friends puchs with 65 or 80 cc metra kits.

on to the questions, what would be a good kit to put me near the 50mph mark or higher? what exhaust should i run? bigger carb? any suggestions on what i could do to make what i have run better?