[AMSAT-BB] Tuning a circular polarized antenna?

So I just built my M2 yagis for 2m and 70cm. They are both circular polarized. My question is what is the proper way to tune the vertical and horizontal planes? I have always just unplugged one set from the splitter and tuned each plane on its own. But what about when you unplug one phasing cable you are leaving one port open. Does that make sense? Anyway I am just wondering if someone would share how they tune a CP yagi.

Thanks Chad KG0MW