Don't know the kind of ridin the 450 has been through but i would look at thr frame real close for any kind of cracks,check for looseness in the wheel bearings. check for slack in the bearing carrier, look at the air filter and box make sure it is clean and been kept clean check the ball joints for excessive looseness,listen to the motor for any tapping or rattleing noises, just give it a good lookin over. Hope this helps.