REBUILD KIT, CARBURETOR, MIKUNI BST40, SUZUKI, CYLS 2 & 3. Full list of parts contained in the kit: Japanese-made float needle & pilot screw o-ring, genuine Mikuni float bowl gasket, cold start slide shank seal, fuel feed tee seal & vacuum port cap, needle seat o-ring, cold start enrichment feed pipe o-ring, main jet access plug o-ring, diaphragm cover vacuum port o-ring, slide guide o-ring, two felt throttle shaft seals, two stainless steel flat hexalobular throttle blade screws and instructions. All o-rings in this kit are FKM. NBR vs. FKM o-rings