Hi
welcome to the forum!
The Kawasaki's use power-jet or econo-jet carbs. Depends who is talking about them what they are called.
There is an orfice in the bottom of the carb bowl. At higher rpms the carb sucks extra fuel through the hose .
That is a very quick explanation. If you google power-jet carbs you will learn lots.
They are both loved and hated