Probaly a KLX engine bored out to somewhere close to 400CC in some KX frame. I don't think kawasaki is working on a fourstroke but I wish they would come out with something new.
CRG
The bike was built by a company called "Metaltek" If I remember right it is a KLX frame with a KX subframe modified to fit and a handmade aluminum gas tank.
They may not have released any public info, but you know they are working on something. I can't imagine a manufacturer NOT developing a racing four-stroke right now.