I have this brand new Tao Tao 110cc (CT110-2) and I have never been able to get it to go faster than 15mph. I have removed the throttle screw but it just hits 15 and then acts like it cuts the gas and then gives it back like it’s being governed or something

 

Just possible it is governed to 15mph. Tao Taos were not governed in the past but who knows now. A few years back I remember having trouble getting a Suzuki 90 to rev on the bench, after cleaning the carb out, then actually tried it out and found it was governed to walking pace via the internal CDI rev limiter.

 

Can you hook up an inline spark light/tester and see if it's the spark being reduced? If not, the only other thing I can think would be the carb.