Just a thought but I have always thought that the manufactures of our little and beloved ChinaGirl engines designed them with the U.S. federal government guideline of 20 MPH top speed. So they are geared to be optimal at 20, 22 MPH tops.
Any, well most to my understanding, engines of any sort work best at 75% throttle for fuel efficiency, longevity and power out put.
And I still ride the poor dumb and over taxed thing at WOT and yell at it for the vibes and lack of performance.
Really, this poor little 2 stroke engine is turning a 26" wheel and moving my 175 lbs butt at a speed of 30+MPH. And I beech and demand more. (At a lower initial cost and better MPG)
Just funny. I want more but want to pay less.