You have an X series Mid -Bike, with a 49cc piston port engine and a 15mm Walbro WYK pumper copy carb. Even a new engine in the bike it will do about 25-30 mph. The biggest problem is your bike weight, 70 to 90 pounds, alot for a 3hp engine. My A1 Cag is less than 40lbs. My piston port scooter ia about 48lbs. You can do alot of mods to the engine, and double your horsepower. My scooter has a Boosted306 ported head/cylinder. I also built one with an alum alloy head on a cut stock cylinder. The wiring on these China bikes sucks, probably wires touching inside the switch.