BMW F650GS nice and clean ready to go...
Brought: a few basic tools, Zumo GPS, electric pump, quart of oil, replacement tubes, tent and sleeping bag (not used), change of clothes, fleece, rain gear, toiletries, flashlight, etc.
Highly recommended, almost essential: GPS with Mexico Topo Atlas. I purchased mine from the net at http://www.bicimapas.com.mx/ for about $150.
http://www.mapas-de-mexico.com/ has probably the best printable topo maps of Mexico.