Jeff's advise is perfect!
He has explained details I forgot from a year ago while doing the same route.
While doing Baja I decided to keep going (unplanned) and invited Friends to fly and meet me in Costa Rica in 11 days and later continued to Yaviza Panama.
So most of CA was done in a rush but still through secondary roads, with border crossings taking a big chunk of time.
Now as Jeff described, you will have to export and import your bike at all borders, and as a rule (except for a few borders), this is best done on weekdays during office hours because some of the 2 or 5 officers ,agents or banks you need to talk or get signatures, stamps or pay may be off.
If it wasn't for your bike or car you can go through 24/7.
Read Jeff's advice, print it
and keep it in the map drawer to read again before you leave to CA, it is SPOT ON!!
Being fluent in spanish and knowing most coloquialisms and gestures I hepled a few traveling gringos at the borders who would have done things a lot faster (and often cheaper) if they had some basic Spanish.
Again, Jeff is right... learn some Spanish.
Thanks to Jeff for taking the time to write all this for the rest of us!!!