Re: Still sputtering/chugging
Sounds to me like it's running rich, which is totally normal for a china engine. After break in, you can jet the carb to fix this.
I agree with the others, new carbs are dirt cheap.
I run my new engines with the needle clip second slot from the top. (Search to find out what this means as I don't have time to type it all out)
I run 40:1 right from day one, but some prefer 24 or 32:1 during break in period.
16:1 like the "manual" says is FAR too much oil!
If more is better, then too much is just enough.
If you can't afford it, build it yourself.