This is a friends bike. What piece is missing? It was lost during a hare scramble. I believe the rider said there was some oil dripping out. My guess is that is an auto decompression release. I tried to look the part #'s up on bike bandit. Any info will be greatly appreciated. Update. I don't have a photobucket account so I could not attach a picture. It's located on the right side of the head directly above the exhaust pipe. It's a WR 450.