I've owned a 2007 Yamaha C3 and several Taiwanese 50cc two-strokes.
The C3 has the same fuel-injected and water-cooled 3-valve engine as the new Zuma 50f.
Throw some 4.5 gram Dr. Pulley slider weights in it and it will pull 45 mph all day long. It is the only 4-stroke 50cc scooter I know of that can keep up with a two-stroke, but it gets 115 mpg while doing it and has one of the most bulletproof engines ever put in a scooter.