The Voyager contains 7 banks of presets with 128 presets per bank (896 presets total).
The last 63 of those 896 are blank however, allowing you room to write your own patches without erasing over the factory ones.
Bank G presets 66-128 are blank by default from the factory.
You can switch banks by holding down the cursor button and then pressing the -1 or +1 buttons.