Bbr did make a crf150f with a primmy frame and crf250r motor. I don't think they made many, there was an article about that bike but it's just about impossible to find. I met one guy who said he had one but sold it long before I met him and I believe that he really did, their family has had just about every bike ever known. If I had to guess it was probably less than 10 made, maybe talk to bbr and see what if they have any info about it.