[Dave Box]

Well I have to confess that your carburetor has me confused, it really does not look like a BV-18 (although it could be from the same family. At first glance the bolt that you arrow looks like it should be the mixture screw (it is in the right position) then looking to the right of the arrow head you can clearly see a mixture screw so I don't know. I can tell you that the philips head screw at the far right is where the oil pipe used to be whether or not it is sealing the port is another matter. In addition your image shows that there is no provision for the governor to work. It is a small matter but further evidence that it is not the correct unit. I have attached an image of the correct unit.

I can't tell you what to do but I can relay my experiences of rebuilding this engine. I cleaned my carburetor at least three times and I never got the car to run acceptably. Eventually I bit the bullet and bought a new carburetor for ~$99 and the car now runs like a new machine.
Of course you also have an issue with possibly worn seals and my gut feeling is that you will inevitably have to replace them as well.
On the good news front there are many guys who will help you with the seal replacement and when you finish your little 2PG will exceed your expectations.
Good Luck
Dave


Ooops Sorry I just re-read my post and I realize that what I said was not entirely correct. In your picture the low speed mixture screw is in the correct place and the lock nut has been loosened. That big ugly screw that you arrow is where the low speed jet should be. If that screw has replaced the jet and has not damaged the thread I have one that I can mail out foc, just let me know. Sorry if I muddied the waters