Contact cleaner, then a light spray with cable lube. My latest favorite is M1 synthetic spray, but any quality cable lube would be fine. The cable luber attaches by clamping to the outer sheath. Disassemble the throttle tube and free the cable. A spray of WD40 first, followed by cable lube and your throttle will be like new smooth. A small drop of silicone based grease on the throttle tube where the ball goes in, and a dab inside the housing run halves before you screw the assembly back together. Do the clutch cable and pivot while your there. You may be surprised at how different things feel. Remember.. chain lube is not cable lube. Chain lube gets sticky after the carrier evaporates, and makes the controls gummy instead of smooth. Just my .02 after wrenching for several amature MX riders and my own street bikes.