I had the same problem getting a rear bearing for my 65cc Stihl four stroke. They wanted $200 for a complete crank rod and bearing assembly.It was easy to find a bearing with the same small dimension. It was the outer bearing dimension that was made a larger size than standard. As far as I could find out they were made in Equador for Stihl only. An aluminum sleeve was easy to machine to a press fit that adapted a standard bearing in its place. It works just fine.

Good luck