Motorcycle Repair: 1978 BC 750K, amp fuse, fuse box

Question
The main fuse, a 15 amp gets very hot. The ground wire from the rectifier got very hot & was melted almost all the way to the coil.  So was the fuse box that held the 15 amp fuse.  I replaced them both. And the main ground wire all the way to the coil, where it grounds.  It's still gets hot.

Answer
Brad, it sounds like the main grounding strap from the battery to the engine case is not making a good connection.  Make sure the terminals are clean, tight and there's no paint or anything under the connections.  The wiring harness ground should not be carrying much current but if the battery cable is not carry the bulk of the current, the little ground wire will be forced to carry more that it was designed for and gets hot.  

Regards
Rich