I acquired a 15hp Yamaha recently with the carb in a box. There is a small diameter tube that is attached to a nipple on top of the carb on the port side . I can't seem to locate where to attach the other end of this tube. I looked on the air box, the other side of the carb, and just about everywhere else the tube will reach. I can't seem to find another nipple. Anybody know where the thing goes? -- Ed.