Provided you come back before it expires you only need to notify customs office at the border.

+ 1 on what richsuz said about the Guatemala TVIP

DO be careful not to misplace or lose that or any other document, .
Not finding these papers is a guarantee for a long delay at the customs
office on the return trip.

A bit of a headsup for the eventual return to Mexico Babbalouiex . Since you left
Mexico at an unstaffed border crossing you probably still have both your Mexican. Tourist Card and TVIP . The TVIP will not create a problem because
you would have been allowed to keep it for the return trip on Mexico.
With luck and an understanding border worker your UNCANCELLED Tourist Card
also may be overlooked . Really, when crossing into Central America the Tourist Card must be cancelled and you should have had an Exit Stamp placed in
your passport below the Entry stamp of this trip when you crossed from
the USA..
Basically you are all set for the return through Mexico so when coming back to Mexico simply ride your bike
right through the border facility, show your documents if asked but
don't volunteer any information .At least you should have some
benefit from crossing out at the unguarded border .
Remember to cancel the MEXICAN TVIP before heading back into theUSA,
and be sure to get your bond refund........OR.....
If you sailed past blithely and avoided all the required customs processe when you first
entered Mexico from the USA then you will have to get the Mexican Tourist Card andTVIP and pay
the refundable security deposiit.
And take note, depending on where you cross to the USA you may
be able to that cancel and refund performed at a customs terminal/ checkpoint
many km before the actual border crossing in a city. Pay attention .

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http://advrider.com/index.php?thread....207964/page-5 then scroll down to post #93

Thank you for the information, guys. I still have my Guat and Mexican tvips so I should be good.