Typically, migrating a virtual machine from one Hyper-V host to another would involve System Center Virtual Machine Manager, however, if you do not have that software or do not want to use it, you can follow this guide to move virtual machines manually. The drawback to moving the virtual machines manually is the machine has to be powered off. The total amount of downtime depends on the size of the virtual machine.

Begin by shutting off the desired VM. Open the Hyper-V manager at Start > Administrative Tools > Hyper-V Manager, right click on the desired VM and choose Shut Down:

Now right click on the VM and choose Export:

Choose any folder to export the VM to (whatever folder you select, a sub-folder will be created with the name of the VM and all of the data files will be stored there). Depending on the size of the VM, this could take anywhere from 10 minutes to several hours: