I believe that livecd-creator default iso size is about 4G. You need to change the size of the / partition to 8G, etc.
Here is a copy of the fedora-base-live.ks (beginning part, at least) which is where you make your changes to iso, language, keyboard, etc:
# Defines the basics for all kickstarts in the fedora-live branch
# Does not include package selection (other then mandatory)
# Does not include localization packages or configuration
# Does includes "default" language configuration (kickstarts including
# this template can override these settings)
auth --useshadow --passalgo=sha512
firewall --enabled --service=mdns
part / --size 8192 --fstype ext4
services --enabled=NetworkManager,ModemManager --disabled=network,sshd
I have already changed the size of "/ part" to 8192 megabits (8G). livecd-creator will always stop with an error if you try to create an iso larger than what is configured in the fedora-live-base.ks. If you are not using this file then add these configuration lines (9) to the beginning of your kickstart file. Make sure you place these lines before "%include, %pre, etc."
Hope this helps.