its more likely to be the neighbour who seems decent and chats to you thats stuck you in to try and put the suspicion onto someone else. burn everyones houses down just to make sure.
you can nip it in the bud by telling them who owns the motors to put an easy end to it or you can make it awkward for yourself by not co operating but if you make it awkward theyll all be harassing you for all sorts of bollocks in future..