Stem Seals For Lifan YX 125cc 140cc Engine Pit Dirt Bike Motorcycle Spare Parts Designed to match Fit For Lifan YX 125cc 140cc pit dirt bike engine stem diameters for accurate installation Forms tight oil blocking seal around stems to stop excess from entering combustion chamber Reduces blue emission prevents carbon buildup on spark plugs, valves cylinder head parts Made of temperature rubber composite material that withstands continuous engine operating Uniform dimension consistent with seals, no required during engine rebuild assembly