if it has an aftermarket clutch kit in it the thrust bearing is probably smaller than the original,thats why it has the clamp there but the correct way to fix it is adjust the ball that the fork pivots on . the thrust bearing doesnt need to be much shorter to cause problems because your clutch works on a leverage system .i have had this problem twice and have fixed it by adjusting the ball that the fork pivots on . it only takes 1-2 mm adjustment