Thunder on the swing arm 125 which does not allow wide tires wear my suggestion to find a replacement or cross the appropriate part.
Could use a swing arm that the 250 Thunder installation needed adjustments. To remember not too push too wide considering the size of 125 cc engine would be an impact on the pull, the second alternative with the alternatives in the form of custom reply can be more exclusive.
So from my hopefully useful, thank you. http://modofikasimotor.blogspot.com/