Bootcamp startup problem after Winclone

hologram said:

I just installed Win 8.1 on my5k iMac internal SSD via Bootcamp. Everything went fine and it showed up in the Startup Disk preference, and at boot holding down the option key, as it should.

Then, using Winclone, I backed it up to an external drive and got the “successful” message when it was done, which should make it bootable and available in the Startup Disk prefs, but instead neither one shows up, either in the Startup Disk pref or at boot holding down the option key. If I disconnect the external, the internal Bootcamp still doesn’t show up in prefs or startup, even after a reboot, although it's visible on the desktop..

The only way to get it to show up as a startup disk again is by disconnecting the external and using a free utility called BootChamp. With that I can boot into Windows from the internal, and then, when I restart back into OS X the Bootcamp partition shows up in system prefs again. Without using BootChamp the only startup option I have is the OSX volume.

As per the Winclone instructions I right-clicked on the external and chose Make EFI Bootable, and it does, but the disk still won’t show up in any boot menu.

Could it be that I’m using a a FW > Thunderbolt adapter to connect a Firewire 800 external? Does it have to be a native Thunderbolt or USB3 drive? Or does anyone have any other ideas?

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How about using these steps instead to directly install Windows (UEFI) into the external drive:

Connect external drive to Windows VM. You must have a Windows VM in VMware/Parallels/VBox, or a Windows PC. Any existing Windows environment will do.

What you need:
install.wim file (obtain this from your Windows ISO)

Open elevated cmd.exe (run as admin)

Note: All commands aren't case sensitive, including pathway to files.

Type diskpart
Type list disk
Take note of the disk you want to select
Type select disk 1 (if your disk is Disk 1)
Type clean
Type convert gpt
Type create partition EFI size=100
Type format quick fs=fat32 label=EFI
Type assign letter=S
Type create partition primary
Type format fs=ntfs quick label=W2G (or any other name you wish for label)
Type assign letter=E
Type exit

Open up File Explorer. In your C drive, create a new folder named WIN2GO.
Put the install.wim file in this folder

Back in cmd.exe:
Type dism /apply-image /imagefile:C:\WIN2GO\install.wim /index:1 /applydir:E:\ (this process will take quite a while)
Type E:\Windows\System32\bcdboot E:\Windows /s S: /f UEFI

Restart your entire Mac. After the chime, hold down Option and when prompted to select your boot drive, select EFI Boot.

Proceed installation normally.

After installation, install Boot Camp drivers. Feel free to trash the VM once you're done too.

For best results, use USB 3/Thunderbolt. If you don't have USB 3, use Thunderbolt. If you have neither, stick back to the internal drive