From 13/14 y/o till 18/19 y/o, I was quite a bit obsessed with 4 stroke/49 CC (one cylinder) Hondas. Owned 6 of them throughout those years. Some examples..
C50 (without the white plastic 'leg-protect-thing'.. that sucked and always had to go)
CD50
Still have one similar to this one in my garage.
The thing is as old as I am.
Or, to give you an idea of the gorgeous sound they make, this yatube vid..