Trusted mechanic in southern Mexico?

[roadgoeson]

Hey all,
I am traveling with south along the Pacific coast in Mexico with a buddy on a couple of Yamaha WR250Rs, with the intent to continue through Central America and beyond. We haven’t had any major mechanical problems so far (knock on wood), but want to keep it that way. So we’d like to have a good mechanic take a look at the bikes to make sure that we, a couple of guys with no mechanical experience to speak of, haven’t overlooked any actual or potential problems with the bikes. We’re tentatively planning to head through Oaxaca (city) and then through Chiapas on our way to Yucatan. If anyone has had any good experiences with a quality mechanic in these areas (especially one familiar with adventure/overland travel and/or Yamahas) we’d be grateful for a recommendation!
-Elijah