Yes. Thanks for that. I had same issue as yours. The check valve was hanging sideways and not working correctly. Once I got the plastic panels off I see lots of QC issues; Mismatched bolts. Missing screws. Wires and vacuum lines routed poorly. Chain is super tight. But I knew all that from reading about these bikes before I bought it.
The carb is marked Sheng Wey PZ20.
I was gonna start by bumping up the idle, it was too low. But today it doesn't want to start at all. I knew I was buying a stack of parts. Now I get to do the set up!