The 78 tank has a filter which inserts into the bung that the fuel tap is mounted upon. It can be a real b!tch to remove, and even harder to remove it intact, particularly if cemented in with rust. That filter works very well when undamaged, though. However, I have a feeling the builder bent you over the workbench and took liberties with many of the details needing to be addressed on this bike.
I'm not very impressed with your builder. But, it seems you specified a "look" and expected him to sort out all the changes from stock, as well as the adjustment changes required to make these parts function well together. I think you got an assembler, rather than a mechanic.
Honda had a team of engineers and technicians contributing 1000's of man hours into making a well rounded and reliable street bike. Changing the looks toward that of a race bike, means an equivalent amount of man hours to make it work nearly as well at the factory techs did. Unlikely you paid him enough to do that, even if he had that capacity. But of course, I'm just guessing.
This is just to give you a flavor of what you can look forward to as far as a learning curve is concerned. The only functional "recipe" for a bike that behaves as it should is the factory specs., which would be the most direct and easiest way to make the bike imminently streetable.
With no tools, no place to work, and no real knowledge of what you have or how it is supposed to work, you are pushing a rather large rock up a steep hill. Yes, it is doable, with persistence, patience and perseverance.
Easier to modify something that already works, than to cajole a crude assemblage of parts into a well rounded and balanced machine.
I did listen to the video.
You really should get the Honda shop manual with supplements. Yes, you can still drag the answers from us, once you learn the correct questions to ask. It will at least tell you where the idle speed adjust knob is located.
I question if all cylinders are firing. Check for cold(er) head pipes. They can tell you if all the jugs are contributing something.
I don't really care if you paid someone else to do a tune up. Until you do the 3K schedule yourself, you will never know if it was performed properly and completely.
Drain each carb bowl, catch the drainage, and examine for sediment. If found, you must locate the source and fix that. Clean carbs won't stay that way with a constant source of crud.
With the pods and pipe, you WILL have to learn what the pilot jet, main jet, and slide needles are set to. (Unless you trust your builder to have made these corrections for you.)
Got a vacuum balance apparatus? You are going to need one with all the carb adjustments coming in the near future. Also, you will need access to either a Dynamometer, or a test track to make full power acceleration runs. This and learning to read spark plugs will help you find the correct main jet for your mods. You wanted a race bike? They just don't come into being with simply an assemblage of parts. They are tweaked many times over.
It can be a fun and highly educational hobby, or a living nightmare. Either way, it will interfere with your desire to "just go for a ride". Be prepared.
If this bike is to be your "main ride", you will learn to hate it in very short order, I expect. Or, get very smart and savvy about it, very quickly.
Good luck!
