Needle and Seat Kit For Tecumseh Part # 631021, 631021B, Made To Be Compatible With Up To 25% Ethanol In Fuel. Quality Aftermarket Carburetor needle and valve kit Made to exceed FSP specifications, can use with ethanol in fuel. Repair Kit For Tecumseh 631021, 631021B OK to use fuel with up to 25% Ethanol with this kit Includes needle valve, seat, and bowl gasket.