Thanks for the ideas. Yeah I do cover it up every night, but it rained when I went to class yesterday so water got in the throttle. When the temperature droppped overnight my moped was covered, but the water inside the throttle froze.
I'm thinking of fabricating a loop from a plastic bag and keeping it down with 2 rubber bands (one on the throttle, one on the handlebar). I hope this works. I'm also trying to figure out a way to keep water off the throttle body on the carb (maybe more plastic bags).