I would like to buy a used 99 XR650L that runs perfectly.. A little black smoke from running rich but seems to be in excellent condition. However, I noticed that the "Pair Control Valve" is missing?? What is this and does it need to be on the bike. It runs great without it and the current owner has put 4000 miles on the bike without it.. Someone please help. I will email a beer to however answers first For those of you who don't know what this is; it is the valve/part that sits on the left side of the cylinder head.. It is completely gone and previous owner said he bought it that way.