I use a spray can lubricant called "6-in1 oil". Just spray it down the cable end and it cleans and lubricates at the same time.

 

Halfway down the cable between the front fender and engine is an adjuster with a pleated rubber cover. Slide the cover back, loosen the lock nut, and you can adjust your cable tighter or looser as needed. Spec is 1/16-1/8" of gap when the clutch lever is at rest. Put a light coating of grease on the metal parts of the adjuster and the boot will slide easier in the future. Don't forget to tighten the lock-nut when finished.

It is advisable to first make sure your clutch is adjusted at the primary first, however. Remove the Derby cover and you'll see an Allen screw dead-center of the clutch basket with a lock-nut around it. Loosen the lock-nut while holding the Allen screw, then turn the screw in by hand or very lightly with the Allen wrench 'til it stops, then back off 1/2-turn (CCW). Hold the Allen screw in that position while tightening the lock nut firmly without over-tightening. Spec is 72-120 in. lbs., but since torquing is difficult on this nut because a socket won't fit while holding the screw, I just tighten firmly with a box-end wrench being careful not to over-tighten. If you want to torque the nut I think you'd have to use a crow foot.