Mexico is a huge country with everything from goat tracks to well maintained toll highways. Unless you're planning on going off the beaten track, any bike will do for Mexico. Toll highways are insanely expensive but will get you there much, much, much, much faster. Google "Traza Tu Ruta" for the rudimentary Mexican version of Mapquest. It'll give you toll costs for whatever route you choose. The peso is worth about 7.5cents US.
Things to watch for are livestock on the road; serious potholes appearing out of nowhere (on the non-toll roads); topes (speed bumps) marked and not marked. Extremely slow trucks on steep roads just as you round a corner. When a road is extremely narrow, such as the road between Durango and Mazatlan, expect trucks to be coming into your lane when they negotiate the curve. They have no other choice and you have no other choice than to come to a stop to let them make the turn, lest ye be crushed like a bug.
Driving in Mexico is actually quite a lot of fun as long as you know how things work down here.
On the highway a left turn signal means "go ahead and pass". When pulling off the road or making a left turn they usually use their 4 way flashers. Truckers and bus drivers are usually pretty good at using their 4 way flashers to let traffic behind them know not to pass them when the see other traffic oncoming.
Don't follow trucks too closely or you might suddenly be faced with a rim crunching pothole without enough time to react. Signs indicating curves don't seem to have a lot of consistency. The sharper the angle of the curve on the sign, the sharper the curve. But a sign for a sharp curve seems to mean anything from "slow down to no more than 40km/h above the posted speed limit" to "even think of staying at the posted speed limit and you're dead". Exagerating a bit, but you get the message.