I own a '98 454 with 3800 miles. Have changed all 4 ball joints and front shocks. Front wheel fell off when ball joint came apart last winter. No previous sings of wear. Same thing happened to a friends '96 454 this spring. Bike had about same miles. No previous signs of wear. Also have problems with back firing same as the 300's. Friends does the same thing. Anyone have similar problems with ball joints? Any ideas to solve back firing?