Increases the cam plate pressure relief pop-off pressure. The Feuling spring has the proper spring rate to control the pop-off pressure and oil flow in the by pass port. Bench testing recommended with the Feuling cam plate pressure test tool (566117 for Twin Cam only) allows you to set your pop-off pressure to your preference. OEM replacement reference 26210-99. Note: Feuling recommends bench testing with the Feuling cam support plate pressure test tool; 566117; to set pop-off pressure to your preference and to ensure correct valve seal and valve operation.