Try 0.5v as a base and up to 4.8V is OK , let it warm up for a bit so the ECU learns the new setting , it will talk to your idle speed controller to set a stable idle.
Hyosung makes a lot of manuals but sometimes don’t always include every little detail (some manuals have more details than others), but the 650cc manual isn’t too far off (Both 650 and 250cc used DAEWOO ECU’s on the early models but obviously a 650cc ecu won’t work on yours)
I never paid attention to the OEM values as if a TPS went, I just replaced it and used a good judgement and set it.