Truthfully speaking, I get annoyed when companies BUY a motor from another company, put it in their bike and call that bike their label. What did they do then? Nothing. That bike is just a Rotax, it's not a Maico.
EDIT: Note I am only referring to companies that just buy a stock motor from another company, some companies do work with other companies on design and that's a different story. But to go to buy a pretty much off the shelf motor, like a rotax, is what I am talking about. Like if I bought a Zabel or Maico engine from Koestler and put it on a frame and called it an OpfermanMotors bike.