Carbs and idle woes

So I'm looking for a little help. Bike is a '76 kz400 d3 with a single Keihin Pwk 35 carb. Purchased about 6 months ago. Replaced the copper manifold with a properly welded 2-1 manifold to solve air leaks I was experiencing. However, I can't seem to figure out my high idle.

Two days ago...
Pilot jet: 35
Main jet: 145
Needle clip position: second from top

Motorcycle would kickstart, without choke, easily. However, idle would hang around 2,500 RPM's. I could adjust the idle screw but it would only increase in idle. The only way to get it to drop would be to adjust the air screw by nearly seating it. However, the plugs were black indicating a rich condition. Carb has been thoroughly cleaned so I assumed my pilot jet was incorrect.

Today...
Pilot jet: 40
Main jet: 145
Needle clip position: second from top

Motorcycle will not kickstart without opening throttle. Once it starts, the can be lowered to roughly 1,000-1,500 RPM's. However, it seems to want to run better at the higher range. This time I'm within 1.5 - 2.5 turns out on the air screw.

So to recap...I only changed the pilot jet from 35 to 40. Starts harder but I can decrease the idle more than before.

From research, opening throttle durning starting = preventing the enriching circuit from working ... only air (leaner condition.) However, with the smaller pilot jet, I had to nearly seat the air screw (richen) to get the bike to decrease in idle.

I'm lost in all the data. Some things tell me it's too rich, while other thing tell me it's too lean. Tomorrow I'll spend some more time with it in it's current setup. In the meantime, does anyone have any suggestions or care to school me in carb tuning 101?