Technically it is a Throttle Friction Adjusting Screw. Like many of you I have had mine apart. It is obviouslly NOT for anything but what it's name says. With the bike not running, I turn the screw until I can feel it add a little friction and leave it there. Then make sure that the throttle returns to idle on its own at a decent rate. Not slapping back, yet not dragging and hesitating. I would not use it as a throttle lock