Gents,
Getting cold and I always have to richen the idle mixture screw (turning clockwise). I always adjust until it stops pinging. Usually ends up about 3/4 turn out. Is this the correct way of adjusting?

 

The idle mixture screw is actually called the pilot air screw, it's purpose is to adjust the idle mixture. It only affects idleto about 1/8 throttle. If you are under one turn out you are too lean and should go one size larger. Conversly if you are more than two and a half turns out you are too rich and should go down one size.
The engine should be at a normal operating temperature when the adjustment is made. Then turn the pilot air screw in until the engine runs rough aor slows down, then turn it out until the same thing happens. Be sure to count the number of turns as you will take that number divide it in half and turn it in that number.
If you have detonation and are sure that your timing, fuel,VOES and spark plug heat range are OK then you need to look at two other things, ffirst is the accelertor pump setting. It should be about .081 to start with. If it is ok there then you can back off on it until you have a problem again the go back a little until it stops. That will give you the best all-around performance and mileage. The second thin is the metering rod, you can raise it one notch to richen up the midrange. When you take the top of the carb off you will see it setting down there held in place by a small metal "hook" and allen screw. Just loosen up the screw and push it aside, DO NOT REMOVE THE SCREW. If you do it will fall down into the bowels of the carb and without a lot of luck you will have to have the carb disassembled. Hope this helps.

 

Thanks MIA,
I'm a little confused. I thought turning the screw in richens the mixture because you are shutting off more air. Backing the screw out let's in more air. Do I have it ***-backwards? The carb is a stock 42MM, not sure what jets are in it or what groove the metering rod is in. What are symptoms of being too rich?

 

You are correct, that is why if you are in less than a turn, you should put a larger (richer) jet. If your carb is unmolested the needle clip should be in the middle groove. The jet can vary, but a 20 is common for sportsters with a 25 most often for big twins.
Too rich could have plugs fouling or very dark colored, poor mileage, or poor performance to name a few.

 

Ok took the big sucker off last night to get a better shot at the bowl screws. Yep, it's true what they say, freakin' screw head rounded out. Have to take the carb off and drill it out when I park it for the winter. Still got a few weeks of riding and don't want a project. I should have checked the jet sizes when I got the carb. Mikuni said it was plug and play, but at a little less than 1-turn out I'm thinking I got a 20 pilot jet. Maybe I got a carb set up for a Sporty. I have it adjust now so that it doesn't spit out the air cleaner. As recommended I think I need to get 'er hot, park it in neutral, set the idle high. and make adjustments. Do I have it right?

 

Not quite, leave the idle at around 900 RPM and adjut the mixture. DO NOT DRILL OUT THE SCREWS!!!! If you are just a little off you will have an expensive paperweight!!!!!!! Get a good pair of small vice grips and loosen them that way. You need a good #2 phillips to install and remove the screws. A hand impact driver with a light hammer will loosen them without stripping them out. Hope this helps.

 

I know Mikuni says not to, but I replaced my float bowl screws with socket head cap screws. Just don't overtighten them. Just a bit beyond snug is all you need. They're metric 4mm IIRC.