I dont know what the Colombian was thinking when he bought your Chilean plated bike There is no way in Hell its going to be Plated Colombian
But Its Colombia they have ways That I would never Try
I entered Ecuador in November last year from Colombia I returned this year in feb into Colombia I had ten days left on my tourist visa and the lady at the San Miguel crossing asked if I wanted to extend my visa for another 90 days, I said no thanks ill pass and asked her about how much time I would be allowed coming back to Ecuador this year
she replied 10 days and I would have to apply for a 90 day extention
Ecuadors system is different and I'm not sure on how they reset your time to stay 90 days then apply for a Extention for 90 more
In Colombia this is strait forward
As far as buying and registering a bike in South America, crossing borders shouldn't be a problem, you won't need a temporary Import Permit This only applies to vehicles that are not from SA
When I entered Ecuador in November at San Miguel the crossing was easy peasy Going into Ecuador the officials never even looked at my moto Though I was standing in Migration with riding gear and helmet, Same coming back to Colombia
The Colombia/ Ecuador migration officials are 10 feet apart Stamp out stamp In
it doesn't get any easier, Colombian plates rock