Re: What's this?
I can't tell you what it is. But it reminds me of a Suzuki that was in my neighborhood a few years back.
This bike had a similar profile. And, from the looks of that curb and the bushes in your photo, a similar overall size.
It had an upright single cylinder with an exhaust pipe coming off of it that looked to be nearly the size of a tennis ball. The model was 'some letter' followed by 45.
I found myself wondering it that could be a 45 cu inch single. It's not impossible.
If so, cool bike.
But I'd even be okay with that 125 cc lifan. Or whatever. Small is not necessarily bad.