"Our factory manufacture various of carburetor"
Runtong is a Dellorto SHA "shaped" carburetor (the word clone would be insulting). It features a 15mm bore and a lever choke. The float bowl and top cap are both made of fairly low grade plastic. These can be found on eBay for as low as $11 shipped from Hong Kong. It uses a single brass jet which is un-marked. The carb does not come with any air cleaner, or air box.
First off, the choke might not work (mine was defective). Remove and throw away the bent up auto-release. Stretch out the choke return spring a bit and re-install it on the choke pivot screw (do not hook it to the choke lever) to create an interference fit. This will allow you to set the choke lever in any position you like.
The main jet is a mysterious beast. At first glance, it looks like a typical Dellorto 5mm, but it isn't. It's 6X0.75mm This is not the same as Dellorto 6mm jets which are a finer thread. You will need a 6X0.75 die and the Dellorto 6mm jet of your choice. Clamp the die gently into a vice and find a short handle screwdriver that fits the jet snugly. Carefully twist the jet into the die to cut the correct threads in it. It comes out looking surprisingly clean considering you are cutting threads into other threads. Twist it in and out of the die a few times to clean it up then use a brush and carb cleaner to remove the brass filings.
Yes, you got what you paid for. But, you can make it work!