Avoid coolant leakage Tight closed cap, fully TIG welded and threaded with an Oring gasket to create a secure, sealed environment and prevent coolant leakage. Maintain operating temperatures The radiator coolant overflow tank helps keep engine coolant within the operating temperature range when the engine is running at optimum performance. Coolant returns to the radiator As the coolant cools and contracts, a vacuum valve in the pressure cap opens to the coolant that flowed into the overflow tank back into the radiator. Before ordering Compare the product image with the photo of your motorcycle radiator and verify your motorcycle model to ensure the part fits your model. Installation and compatibility notes Installation instruction is not included. Professional installer is recommended. Use scenarios For motorcycles used in long rides, sport touring, or hot conditions where coolant expansion is likely, to help maintain cooling performance. When upgrading or replacing an existing overflow system to achieve a reliable, sealed overflow and flow. During regular maintenance to ensure coolant can to the radiator as it cools, supporting stable engine temperatures.