Howdy everybody. My first post. I will say I have 3 KX500's a 1987 a 1994 and a 2000. I picked up a clean 87 in January and it needed some tlc, one of the first things I noticed was the left exhaust valve was missing. I am just not seeing them on ebay. I did a fresh top end on it and removed the remaining one. I don't notice any difference. I'm about to order a fmf pipe for it and see if my power picks up some from the stock one which is clean and dent free.