What do you do if the clutch cable will not adjust on a harley?

It depends on the year and type of Harley, but on a late model Big Twin if the clutch cable can't be adjusted it can mean one of several things, the worst being a fried throwout bearing.

If there's no indication that the throwout bearing is bad, it may mean the ball & ramp clutch actuating mechanism (in the tranny end cover) is temporarily stuck in the "disengage" position. Usually just moving the cable end in and out will put it back into its default position.

It's also possible the clutch itself (not the cable) was incorrectly adjusted, in which case it's simplest to:

A) Fully shorten the cable sheath (at its adjuster)

B) Loosen the locknut at the center of the clutch

C) Screw the adjuster all the way in until it stops then back it out 1/2 turn

D) Retighten the locknut

E) Readjust the cable