The first thing that I would do is order a new side cover gasket and go inside the engine and remove that arm for the governor. You can then put a paper towel in there and tap the hole to put a bolt in it. I highly recommend removing that because if that pin comes out there's a good chance that you'll need a new engine. You will need to clean the engine thoroughly with carburetor cleaner to remove any shavings left behind.
Second I would rig up a throttle linkage like the ones used by red beards garage.
As shown in this video:
https://www.youtube.com/watch?v=STNiG8sIQLg
This is done on a GX200 which uses the same throttle setup as the 212s. And if you don't have the throttle setup from factory i would invest in a top plate or half top plate. Both come with a throttle linkage and the extremely important return spring. I say extremely important because the last thing that you want is to have your throttle cable stick at full throttle.
And when you say that the carburetor is a new stock one do you mean that you bought it brand new or the person you bought it from said that it is brand new.
Also I noticed that you have a header pipe. Do you also have a performance air filter or are you using the stock intake? If you are using a stock carb jet with a performance air filter and a header pipe the engine will be running to lean and you will need to use a carburetor drill set to drill it out some. Or you can order a drilled jet online.
The drilled main jet can be found here:
https://www.gopowersports.com/clone-carburetor-drilled-main-jet-predator-212cc/
Use the .38 jet
The side cover gasket can be found here:
https://www.gopowersports.com/side-cover-gasket-012/
And the top plate can be found here:
https://www.gopowersports.com/top-plate-for-212cc-non-hemi-predator/
This is for a non hemi which based on the valve cover is what you have.
