REBUILD KIT, CARBURETOR, MIKUNI BST40, Full list of parts contained in the kit: float needle, needle seat o-ring, cold start enrichment feed pipe o-ring, float bowl gasket, pilot screw o-ring, slide guide o-ring, cold start plunger retainer to cable seal, 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