Im building a CA street legal XR50 motard. I need to work with the stock fram because it has the VIN. I want to put an "H" type swinger and rear disk brake. Has anyone seen or made a bracket that will hold the rear brake master cylinder?
BBR makes an adapter that you can purchase for use with their disc brake kit for stock style frames. Pretty spendy though for what you get. Part number is 550-HXR-5050.
With a bit of fab work its pretty easy to get something set up yourself if you have some basic fab tools / skills. If not contact Gary @ Sik Tendencies Racing. He is the disc brake guru when it comes to minis. His email is garymarshall254@hotmail.com
Here is a picture of the BBR setup:
Its under Products--->XR/CRF50---> Disc Brake (Rear)