I have a 03 kx250 that had a problem like that. found out that when I turned right it did the same thing and it was the handlebars were to high off the bike and the clutch lever was to far out. And when you turned right the cable would tighten up and pull the clutch lever in. check to make sure the cable isnt tight turning both ways while you have it on a stand . you might have to adjust it. You should have play in the cable when turned all the way lef or right.... good luck muckyman