The previous owner took his DRZ to a Vancouver Suzuki dealer to have a big bore kit installed. He was not confident so he dished out the big bucks and had it "professionally" installed. Fast forward 3 months and I buy the bike. After daily abuse I could see some oil leaking from the valve cover. I pulled it off and found silicone all around it. I could not understand why there was silicone until I looked at where the valve cover mounts to. It threads into the top of the cover that holds the exhaust camshaft. The cover was over tightened upon reassembly and then taken apart, siliconed, and then reassembled. No word to poor owner. Really, I doubt the mechanic even told his/her superiors. I can't buy the cover because it is a mated fit so I have to find a fix. Any suggestions, machine shop, mechanic? I thought about using a heli-coil but I don't have any experience and I would prefer a mistake to be less costly.