How do I change the mix ratio on the XP Proportioner?

To change the mix ratio, one or both high pressure displacement pumps need to be replaced, the air motor needs to be re-positioned, and the over pressure relief valves may need to be changed. Check the XP Pump Assemblies table for correct pump sizes, remove and replace the pump, adjust the motor position, and if changing between XP system types (e.g., XP50 to XP70), remove and install the correct Over Pressure Relief Valves. Also change the Air Pressure Relief Valve (MG) as required depending on the ratio. (Page 42)