Yarp - and there's been some attempts to work them into a bicycle;
Potential problems include size but more problematic - shape, drive, and interestingly enough, many pocket bike engines in a similar price range are of no better quality than the China kits you don't like... as they're also made in China lol
I'm not sayin' it can't or even shouldn't be done - I'm jus' wonderin' about the distinct lack
of pocket bike repowered bicycles when the engines are so common...
For the dough - I'd still get a Morini, unless it's the MacGyverism yer after... then anything