I have a 93 Sportster and when turn the ignition on the speedometer cable gets real hot and starts smoking. I have followed the wires I can see and i don't see a short anywhere. Anyone have an idea of what to take off and look at.

 

Disconnect the speedo and see if the cable still gets hot. I suspect it won't.
A wire shorted to ground will get hot between the voltage source and the point of the short.
I think you may have a bad speedo.

 

A short in the speedometer would not cause the cable to get hot, it would cause the wire between the speedometer and the fuse to get hot...

The problem is a bad ground...

The speedometer has a black ground wire that should be connected to the upper fork bracket, if this ground is bad, the voltage will simply find another way to return to the battery, in this case it is running through the cable until it gets back to ground.

 

With 'cable' being a multi-purpose term, I was thinking electrical cable.
What Dan said is correct, if the speedo unit is seeking ground.
The ground wire on the fork tree is usually a culprit of electrical issues.