I agree that it's fake. I've responded to bike accidents like that.. And people look like that at 60 mph crashes.
What tips me off is that everything is all together in one frame. During a motorcycle accident it's common to have 200 feet or more between chunks of meat. To have all that land in the shot isn't believable.
Also, were it above a 90mph crash where the body looked like that, the bike shouldn't be as together as it was. Fire or not, that bike was too complete to believe something happened at 120+mph.