VINTAGE to me... I'm with Tony, it's air cooled, twin shock, drum brakes. Say Pre 1980-ish. I used to believe it was only Pre 75, but I am relenting. That said, I love OLD dirtbikes, maybe I could call it CLASSIC? Pre 85. I don't agree that Pre 90 is CLASSIC or VINTAGE, but I wouldn't die in a ditch over that.
Of course, I realise that VINTAGE to a 30 year old would be a different thing...