REBUILD KIT, CARBURETOR, MIKUNI BST33, SUZUKI. Full list of parts contained in the kit: Needle seat o-ring, cold start enrichment feed pipe o-ring, main jet access plug o-ring, slide guide o-ring, two felt throttle shaft seals, two stainless steel flat hexalobular throttle blade screws, genuine Mikuni float bowl gasket, Japanese-made float needle & pilot fuel screw o-ring and instructions. All o-rings in this kit are FKM. NBR vs. FKM o-rings