sideways
Unfinished projects king.
A 150cc Chinese motor on a kart will fly. 
Yeah that's true, i'm checking gumtree and there's a fair bit of engines for sale. Is it normal for engines to cost more than frames?
found nice 150cc and such, but don't know if that'll be enough for a small buggy. It will be good for karts though, right?
But, for now, a 15hp electric start Honda clone may well doIt certainly would. If nothing else, it's a learning experience; my daughters kart (my first build) taught me what I can & can't do & what I should & shouldn't do so, by the time I got to my kart, I'd ironed most of the bugs out of the build process.
When I was building my daughters kart, I started on a mini buggy at the same time (which has now been hanging in the garage for nearly 2 years because I got inspired). By the time I get back to it, most of it will be scrapped because I now know better...