Since this type of fuel tends to absorb water, is it possible you've simply got a "bad batch" of Ethanol with too much water in it? Maybe drain it and fill up at a different location/brand? When fuel storage tanks get low, the last 10% to 20% of capacity at the bottom tends to have a LOT of water and crud in it.
Maybe talk to locals to find out which brand of fuel seems to work best. As I recall, Brazil used to have regular petrol as well as Ethanol? No? I'm sure you would have found this by now. Or have they converted to 100% Ethanol everywhere?
Checking/adjusting Jetting and mixture:
Using the choke will richen mixture, hopefully enough to determine if that is the problem/solution.
To go the other way (lean) , open the air box cover/door, or pull the air screen out or air filter to add more air flow. (temporarily of course)
Any change? Better? Worse?
If water is in the fuel perhaps you can find products that absorb water from fuel that allows it to be burned and run through? I would think local products would be available since this seems to be a common issue there? Funnily enough, in the US, we use Isopropyl Alcolhol in fuel to remove water!
So this gets a bit confusing!
I would not change your main jet yet. Remember: it only comes into play at full throttle. I would start with the fuel/air screw first. Simple to get to and simple to change.(AKA fuel screw, air mixture screw, or whatever)
Most bikes have this screw plugged up so you may not have access to it.
But its easy to remove plug.
See if you can get a proper idle and better starting. OUT is richer, IN is leaner.
Warm up bike some.
Turn it OUT/Loosen to richen mixture. The fuel/air screw only affects idle and up to 1/8 throttle opening only. Go no more than two full turns out at most. Adjust for highest/smoothest idle.
Next, adjust needle jet clip position. The needle-jet has a clip with notches. Adjust in the rich direction a notch or two.
Next, try a LARGER pilot jet. (Larger number = Rich) Try one size larger to start.
I'm sure you can solve this. Handle carb with care.