[gentoo-user] making bootable USB

[Joseph]

I'm trying to make my 4GB USB bootable and it is not working.

df -h
Filesystem      Size  Used Avail Use% Mounted on
...
/dev/sda1       3.8G  190M  3.6G   5% /run/media/joseph/B885-F1ED

fdisk -l
...
Device    Boot Start       End  Blocks  Id System
/dev/sda1 *     1064   7864319 3931628   c W95 FAT32 (LBA)

Here are the steps I'm following: 
 mount -o loop,ro -t iso9660 /home/joseph/Downloads/install-amd64-minimal-20140828.iso /mnt/cdrom/
 cp -r /mnt/cdrom/* /run/media/joseph/B885-F1ED
 mv /run/media/joseph/B885-F1ED/isolinux/* /run/media/joseph/B885-F1ED/
 mv /run/media/joseph/B885-F1ED/isolinux.cfg /run/media/joseph/B885-F1ED/syslinux.cfg
 rm -rf /run/media/joseph/B885-F1ED/isolinux*
 mv /run/media/joseph/B885-F1ED/memtest86 /run/media/joseph/B885-F1ED/memtest
 sed -i -e "s:cdroot:cdroot slowusb:" -e "s:kernel memtest86:kernel memtest:" /run/media/joseph/B885-F1ED/syslinux.cfg
 umount /run/media/joseph/B885-F1ED/
 syslinux  /dev/sda1

The above steps are from: 
https://wiki.gentoo.org/wiki/LiveUSB/HOWTO

Where is my mistake? 

-- 
Joseph