Yamaha TDR 180, a Brazilian makeshift approach to the overseas TDR 250
Brazil has always held some peculiarities when it comes to the local vehicles market, not just the cars and commercial vehicles but naturally the motorcycles too. It's important to point out there were restrictions against imports from '76 to '90, which in a market where motorcycles previously had been considered more like a leisure vehicle than an affordable commuter, low-displacement models were setting the change to that point of view. Stricter local content policies were also not so inviting to set a local production of a wider range of models in higher displacement classes, since not just the domestic market demand for them wouldn't justify the investment but the logistics to export most of the output posed as another challenge.
So, while a motorcycle culture was starting to ressurge in the '80s, the easiest way to provide newer models presumably more up-to-date with the international offerings was the adaptation of whatever locally-built engine available. One of the makeshift versions from that period is the '89-'93 Yamaha TDR 180, which relied on the very same single-cylinder air-cooled engine fitted to the DT 180 at that time instead of the liquid-cooled parallel-twin from the '88-'93 TDR 250 marketed elsewhere. It might be quite arguable that a milder version of the parallel-twin from the Brazilian Yamaha RD 350 LC could have been a better choice in order to retain a performance level more consistent to its purpose, but once again it's worth remember the Brazilian economy downturns right after the end of the military government, and then the choice for a cheaper engine to be shared with the DT 180 makes some sense.
Other cost-cutting measure that might spark further controvery is the rear drum brake, in opposition to the all-around disc setup fitted to its foreign counterpart. Though back in the day it didn't really seem to bother anybody so badly, now it's occasionally pointed as an example of disregard to Brazilian customers who were offered a supposedly "inferior" product much like the automobile industry still does nowadays. Nevertheless, in spite of any criticism that may arise against either its performance or other features, the Yamaha TDR 180 was actually an interesting development once we consider the context of the period it was introduced. And it still looks cool at all.