Savage
Actually that bike is manufactured in the same plant as the Yamaha PW50. These where sold by dozens upon dozens of off brand companies here in the US.
Xtreme is Xtreme ATV from Arizona
http://www.xtrememotorco.com/ , that is the company that sold that one but they might not admit it.
United Motors, Trans-National Outdoor Power {under The Name Madami}, Terminator Scooter, SunL, and dozens of other importers sold this bike. They are basically a PW50 with differences so not to infringe upon copyrights. There are a lot of Yamaha parts that will work on the bike, everything on the engine is Yamaha.
I have {2} 2004 Brand New ones left, with The United Motors name & 3 yr. warranty on them, one Green & one Blue.