Check this out. I was surfing the web the other day looking into something I thought was cool. Outside of mopeds and scooters I had no idea there were 50cc street legal "motorcycles" still available. My favorite, hands down, is the Aprilia RSV4 50 Race Replica. There are YouTube videos about the Aprilia and I'm sure others, I'm on my way to look myself. Wouldn't it be fun to have one just for awhile?
Now this one is called "Ninja" but I'm not sure it's made by Kawasaki.
Aprilia's RS4 50cc race replica. Two stroke. However, I believe this image, even though it came from Aprilia, is one of their larger RS4 models. I could be wrong but the tires look somewhat larger than the 50cc model's. The engine does look pretty small indeed. I know this is a larger version because it's a RS4. "4" meaning 4 cylinders. The RS50 single cylinder 2-Stroke.
Tao Motor 50 Racer Motorcycle.
Honda Magna Fifty