REBUILD KIT, CARBUERTOR, MIKUNI BST34, YAMAHA. Full list of parts contained in the kit: Japanese-made float needle, needle seat o-ring, genuine Mikuni float bowl gasket, Japanese-made fuel screw o-ring, two slide guide o-rings, air cut valve housing o-ring, two diaphragm cover vacuum passage o-rings, two genuine Mikuni throttle shaft V-seals, two stainless steel flat hexalobular throttle blade screws and instructions. All o-rings in this kit are FKM. NBR vs. FKM o-rings