You know Bridgestone as a tire manufacturer nowadays, but for a few years they produced very competitive small motorcycles ranging in displacement from 50cc to 350cc. Here’s one of the smaller models, a 60cc Sport.
The two-stroke rotary-valve single was good for 5.8 horsepower and it was paired with a 4-speed rotary transmission. I can’t determine if all of these Sports were offered with rotary transmissions – Bridgestone offered a ‘normal’ option on the 175, for example. Either way, make sure you don’t shift from 4th to 1st!
This example (VIN: 15n002200) is claimed to be a ‘great survivor example’ that runs. The original seat cover may need to be replaced, depending on your aesthetic sensibilities, but it’s titled and ready to go. Find this Bridgestone for sale here on Craigslist in West Salem, Oregon for $950.