Hi, I was just in the process of replacing the head gasket on my 03 YZ450 and I also ended up finding that the valve lifter bucket on one of the exhaust valves is broken. According to the service manual it says if there is any damage to the bucket to replace the bucket and the head. I was wondering if anyone has had a machine shop clean up the area successfully? I'm also trying to figure out what caused the bucket to break. I cannot find anything wrong with the valve or spring so it looks like the damage is only concentrated to the bucket and the bore the bucket rides in. Any help is greatly appreciated, thanks.