Never had one myself, but when I was 15 years of age (many moons ago) I visited a mate who lived on a farm.
Farmers sons, mad as they are (this guy was certainly no exception to that rule), he'd taken an old Vespa 50cc scooter and fitted a larger (ill-fitting) 125cc engine to it. This meant meant that the engine was too big for the rear wing, so he'd cut out half of it to get the engine in.
More importantly, it was so side-heavy that you had to counter-weigh the scooter by leaning to the other side while driving. AND the brakes were not working at all.
I was persuaded to test drive that lethal thing, and I remember that it went pretty fast on the country lane outside their farm. I came at some speed with no helmet, knowing that I had no breaks, but then the local bus suddenly appeared in the middle of a bend.. ! It is a miracle how I missed it, and I still don't understand how I escaped what would have been a nasty collosion - with me killed, for sure.
That was a true near-death experience, and I've never been on a scooter after that.