Old and faulty radiator caps can cause steam and fluid to be pumped out of the radiator overflow hose. A replacement cap is the least expensive and easiest way to solve or troubleshoot your liquid cooled bike/ATV radiator problems. Upgrading to a high-pressure 1.6 bar, 1.8 bar or 2.1 bar from the stock radiator cap is the simplest and least expensive way to avoid over-boiling your engine. Raising your cooling system's maximum operating pressure increases your coolant's boiling point, allowing you toride harder and longer. Black finished cap. Universal fit for most Japanese models. High-temperature corrosion-resistant silicone seals.