For permanent (re-)import into the US, a critical piece of information is
whether the vehicle's original VIN number shows that it was originally
manufactured for sale in the US (rather than in a non-US market), i.e.,
that it was originally manufactured to meet USA safety and emissions
standards.
From your description, that it was originally imported into the US, then sold by
a TX dealer, then taken by the buyer and re-registered outside the US/ in Chile, it's HIGHLY likely that the original VIN number will show that it was originally manufactured to US-spec.
You may want to try to verify, if possible from the TX dealer, or from a
Kawasaki corp representative, that the VIN is indeed a "USA" VIN.
IF you're able to verify a US VIN in advance, and if you intend to RIDE it, as its registered owner on a Chilean registration/ plate, across the MX-US land border, THEN you may try to enter it into the US as a "temporary" tourist import, as if you're simply riding here on a short term basis. If you make a "temporary" tourist vehicle entry, then you should be able to do a "permanent" registration in whichever US state you intend, because (under those circumstances) the VIN will show up as a US VIN vehicle when the state motor vehicle agency checks against the VIN database.
BUT, if for any reason, the bike was originally manufactured NOT to US-spec,
and the VIN is therefore NOT a "USA" VIN, then you could be screwed. Under those circumstances, even if US Customs had allowed the bike into the US as a temporary tourist import, any state motor vehicle agency would turn down your permanent registration application.
If you learn in advance that the Kawi is NOT a US VIN/ spec bike, don't even
attempt to bring it in/ re-register it permanently in the US. That's because you would have to pay way more than the bike is worth to [attempt to] conform the bike to both/ separately US DOT safety, and US EPA emissions standards.
See generally:
Vehicle Importation and Certification Requirements
good luck