K&L Supply Air Cut Off Valve Set 18-2792 Heres an inexpensive kit as an alternative to the costly OEM assembly To prevent afterburn generated by a lean fuel mixture when closing the throttle, the cut-off valve temporarily closes the slow-jet air passage, creating an instantly richer mixture Included in these high quality kits are all parts necessary for a complete rebuild. (diaphragm, spring and O-ring) Made in Japan