xe004ADNOH

i have a 2005 honda 400ex that started pulling to the left. tie rods, air pressure are all good. but i noticed my rear axel is tweak a little. i measured the distance between the front and rear wheels at the center of the axles on both side. the distance betwen the right side is shorter from what i mesured on the left side of the quad. witch is what i think is causing it to pull to the left. does anyone know how i go about aligning the rear axle? thanks