Adam:

After bringing your pictures into Pain Shop and working with them a bit, I could see what you have. I've reposted the pictures here, and a crop of one with a red arrow added.

You do have an early FA-65 with the air bleed carb.

There were three problems with the A/B carbs on the 65s, two were easily corrected, the third was not.

First, was just plain maladjustment. The second was the throttle linkage, and the third was lack of a mid range adjustment.

We'll discuss the throttle linkage first, as it's the easiest to correct. Look at the red arrow in the third picture. This is a spring to hold the throttle barrel tight into the carb body, (A second end is there but can't be seen) and if the barrel is pulled out it will open the flow control valve on the inside end; it depends on the barrel being tight to work. If the throttle linkage tends to pull the barrel off its seat the engine will go rich. Check your linkage, if it has any side loading on the throttle lever be sure the barrel is pushed in, rather than pulled out.

This carb does not adjust the way a conventional two needle carb is done. Peak the high speed, then richen it for a 200-300 rpm drop from peak, and leave it alone. Take the engine down to idle, adjust the air bleed for best transition, not for best idle.Generally the idle will be good, but it's better to keep it running than to have a smooth idle with the engine cutting off in flight.

The mid range adjustment has to be done by fuel selection. The larger Saito engines with A/B carbs did have a mid range adjustment, they weren't so critical. My experience is good with 15% nitro in the old 65, but if your mid range seems rich try going up as far as 25% nitro. Or if it seems lean, try going down to 5% in the fuel. Wouldn't hurt to try a tank of both, see which way you want to go. Do reset the high speed when you switch fuels.

Hope this helps.

Fourth picture is an FA-120 A/B carb showing the mid range adjustment disc.

Bill.