YZF600R is a login theme for GDM - Gnome.
This login (GDM) theme is a variation of Andreu Sanchez i Costa's ZX6R theme.
The only changes were to change the image and relocated the username and password prompts.
The image is a '97 Yamaha YZF600R Thundercat.
Drag and drop this theme into the gdmsetup tool to install.