4. LUBRICATION SYSTEM MXU 550EXi/MXU500i Oil Pressure Relief Valve OIL PRESSURE RELIEF VALVE REMOVAL Remove the right crankcase (refer to the "RIGHT CRANKCASE REMOVAL/INSTALLATION" section in the chapter 11). Remove the pressure relief valve and O-ring from the right crankcase. O-ring Piston INSPECTION Check the operation of the pressure relief valve by pushing on the piston. INSTALLATION Apply oil to a new O-ring and install the pressure relief valve groove, and install the relief valve to the right crankcase. Oil Pressure Relief Valve 4-14