...are you saying that the twist does not return quickly??
..if so, then maybe you should lubricate the throttle cable..both at the twist-grip, and the throttle mechanism on your carburetor...
...there should be a rubber boot at the point where your throttle cable enters the sheathe, at the twist, and at the carb...
..pull the boots back, and shoot some spray lubricant into the sheathing, while working the twist...
..load it up really well, because at this point, more is better...clean up the excess after it's all fixed...
..use a lube that leaves a lubricating film behind, not just a "penetrating fluid"...
..i use SPX-50, which i get where i work...it's not commercially available, but there's such products on the market that work just as well...
..also might want to inspect the cable, if lubrication doesn't work...
..look for any kinks or bare areas in the sheath that might have allowed the introduction of moisture into your throttle cable...
..if you find a bad area, then just flood it with the same lube...working the twist to get everything freed-up, then dry the sheathe well...tape the sheathe well and secure it all in a fashion that will eliminate the possibility of future wear...
peace
