What is the engine model? The Chinese generally seem to use the same engine model, although I am not familiar with all the sub-engines under certain model names. For instance, there is the GY6 engine, but there are a few variants of that. If you look at this site, it explains where to find the engine model.
https://ncystore.com/blog/gy6-engine-code
There are probably a few replacement carbs to be found for your bike if you cannot locate the exact one.