Short and to the point, \ changing battery and briefly crossed leads on battery. heard crack and instantly removed terminal from battery. Engine turns over but no spark. I removed the CDI box and removed the white / black wire from the center of the wiring harness to disconnect the safety devices but still no spark. Any thought or suggestion would be greatly appreciated.

 

You have probably blown the CDI or voltage regulator. It is just possible a fuse has gone but reversing the battery terminals usually blows the main one, so nothing works afterwards, as your engine turns over the main fuse is OK.