I was farten around and started messing with both the Pilot Air Screw and the Idle Adjuster on my Mikuni Carb. During some preventive maintenance this weekend, when I took my plugs off they were very black (running very rich). How can I fix what I have screwed up with this carb I know nothing about. At idle after its warmed up, it runs at 900 rpms, when I engage the clutch to fwd it idles at 720rpms. This is a 4400 Black Death

On my motor I run the mixture screw 1 full turn out, and adjust the idle to hold 1170 rpm that gives me a 870-900 rpm in water Idle. I'm running a gutted stock or at times an Old BPS crossover pipe. That's on a MB 45.

the 42 Mikuni the idle mix is an AIR screw. More you open the screw the more air you get (IE a leaner condition), The less you open it the less air you get (ie a richer condition).
Read the mikuni manual to learn the carb.

I read the manual,,, but still, doesn't help the fact I don't know what to listen for. After warming the motor up for 5-10 min. I have it idling at about 750 rpms. It responds well to the throttle and settles nicely back to the 750 rpm range. But with me not knowing what to listen for I have no idea if I have the carb set right or not. Would a short video of the motor running after it's warmed up and throttling it up a few times help if you guys could listen to it? To help me out?

guess I'm solo on this one...

Your Idle seems abit slow, is that in the water? Do you have a performance pipe on you motor? Some of the pipes scavenge the exhaust better than others. If you are running a stock muffler, I would open up your mixture screw to about two full turns out, to lean it out abit, and adjust idle out of water to 1100 rpm. With clutch ingaged out of water that should give you 850-900 rpm. In water it will be 750 rpm or so. When running my BPS Y cross over, I have to richen my mixture, because pipe scavenges exhaust better. And it helps with cold weather starting and Idle. Are you running stock plugs? I like the Autolite 3923 Platimum + plugs.

running the Q muffler and Autolite PP-3923 Platinum.