Haojue motorcycle hj 125-2 has a tight throttle. Why?

Check whether the balance weight on the right side of the handlebar squeezes the handlebar too much inward, check whether the inside of the throttle line is rusted, whether there is too much dust between the handlebar and the handlebar, whether the right handlebar seat is stuck, whether the carburetor throttle is stuck with the carburetor, and whether the throttle line is aging and damaged.