While working on my 2000 YZ426FM, I noticed the seat base was wearing into the subframe cross bar just behind the air cleaner box on top of the subframe. To remedy this, I cut a strip of bicycle inner tube about 1" wide and just long enough to cover the cross bar support between the subframe square tubes. To attatch it I used contact cement(a little on the frame, a little on the inner tube piece), problem solved! This will also work on other wear points of the subframe as well! Good luck and ride safely! David.