Bike bogging after air leak fixed

[Cbguy]

This one really has me scratching my head. I have a 77 cb750 that I bought from a guy last year. It has 9k miles and seems in good shape. I rode it all last year with no issues. It had a lot more pick up than my 71 ever had. It has a stock air box, stock carbs(not sure about the jets though), and it has 4 into 2 exhaust. It needed to warm up a lot for cold starts.
This year it appeared that I lost a mixing screw on one of the carbs while riding so I took the carbs off replaced the screw opened up the bottoms of the carbs and checked the floats and jets (they were all nice and clean) putting the bike back together I noticed that I was missing a bolt on the air box (it seems like it was missing when I got the bike based on how it ran before). It didn't have a great seal between the top and bottom half of the box but I put it back together anyways and it rode well enough still just needed a good while to warm up.
I finally got a bolt for the air box put it all together balanced the carbs and set out for a test run. It seemed to bog down riding on city streets but not enough to make me concerned at first (honestly it ran more like my 71) but then at full throttle in top gear I could only make about 6k rpm's and 90mph (I could hit 114 before with a leaky air box). It just really seems like it's chugging hard when I open the throttle. It actually idles nicely once warm at about 1000rpms.
Thank you in advance to anyone who chimes in. I appreciate your input.

 

[Cbguy]

I think I might just be overthinking this I just need to adjust the fuel mixture screws

 

[Cbguy]

So I reset the fuel mixture screws to the factory 1 1/2 turns and i can get three and four to sync up with number two but number one doesn't seem to change on the manometer when I adjust the the air fuel mixing screw ( 2 3 and 4 are reading at around 100 mm of vacuum and number one is reading closer to 200). the more I'm reading up on it the more this really just sounds like it's low end when you sync the carbs. High end is the jets. I checked out the spark plug for the number one cylinder and it didn't really look lean or rich it was kind of a dull brown color with just a little bit of gray on the edges of the metal prong of the plug. Also I have good spark and no air leaks. Seems like it's bogging down more now when I open the throttle. I am tempted to put on an air filter with more airflow to see if it fixes the problem. Or just remove the air filter to see if there is any change.

 

[hinksy]

It really is some sort of magic I think