that sucks dude. stump jumper probably used to be a real fun bike.
plus all the effort of trying to make those kits work
also, it's hard not to talk trash about what shit those china motor setups are, but this isn't really an appropriate venue - let the dude get his shit back, then shame him for it lol.
And certainly it's not a moped, and the differentiation is wholly worthwhile, especially since there are other forums dedicated to those type of bikes which are better informed and more enthused about them. However it is totally legit in my opinion to post here cuz I'm 100% in favor of dude getting stolen shit back, and we are all regularly scouring the classified everywhere for scooters/mopeds and would also be pretty likely to spy this if it popped up.
I ramble. good luck