Severed the speedo cable on my 18 klx 250s today. Noticed it was full of wires. So what do I replace it with if it's not repairable.... Anywhere online sell them?

 

Looks like the same hall-effect sensor on my '12/
If it hasn't ripped out the harness directly from the sensor, you should be able to splice/section the damaged portion of the harness to get it working again.
One of the first things I did on my bike was to reroute the harness to a more protected location on the fork leg.
Just connect the same color wires on the damaged harness and it should work.

 

Thanks for the reassurance and suggestion m8. My mechanic buddy is going to give it a whirl for me this week.