I have a fastrider engine on my zip. I got it with stock 50cc cylinder , 12.5mm carb and stock exhaust. It didn't have a good top speed and i also f*ked the cylinder putting a sport exhaust on it without putting a bigger carb or upjetting. Anyway that was before i knew anything about scooters, so then i got a 70cc dr evo kit, fitted a 17.5 carb with 72 jet. It went nice, nothing to good. Anyway now i use this scooter daily most of the day and it drinks a lot of gas. Then i put a stock exhaust and down jetted a little bit. It still drains gas. I remember on the 50cc with 12.5mm carb it didnt use a lot of gas and was perfect. So i'm wanting to put back 50cc cylinder and a 12.5mm, my question is how to get the max out of this (what jet, etc.). THanks. I know ill probably get hate on my post but im not too experienced, so yeah if anyone can help thanks.