IMHO, when it comes to CV style carbs - which are wonderful by the way - the absolute best way to learn about, and fully understand the various functions is:
On a pleasant, carefree Sunday morning, Make a pot of good coffee.
With carburetor(s) inhand, sit at the kitchen table (workbench if you are married!). Spread out some newspaper, and take the carb fully apart, piece by piece, and lay the individual pieces out neatly in order. Take your time, sip coffee, be happy...
Now pick up each piece individually, and study it, feel it, understand it's function - both individually, and how it may interact with other pieces.
Blow into the various holes in the venturi chamber (use a small piece of tubing to get at the difficult to reach openings), and understand the path they take, and what triggers them, and what does not.
Blow into the various tubes from under the float chamber, and fully comprehend their path and total function.
See how the slide works, and how it is raised up and down. What makes it rise and fall? What does not?
Plan to take at least about two hours studying the carb, assembling it, disassembling it, and if you get stuck on something, take a break, and go for a short walk outside.
This will arguably be the best two hours you can spend, as when finished you SHOULD obtain a full understanding of "how it works". From that moment forward, you can look away from any future posts about "jetting" as you will have heeps more knowledge than 99% of the "experts" out in cyberville.
It's really a very simple, beautiful device, that is only scorned and abused by those who unfortunately never took the time to fully understand the overall true function. Note how these types often begin retorts with "All I know is...", and/or "It's a well known fact that..." (it is?
). Funny.
Most importantly, comprehend the "Constant Vacuum" (also refered to as "Constant Velocity", Constant Depression") function, and what it does, how it does it, when it does it, etc. This is vital to the full understanding.
How does the Slide rise and fall?
What makes the slide rise and fall, and what does not?
When the slide rises / falls... what else happens? Why?
Once you comprehend the various functions, make sense of how, where, when, and why the various fuel feed and mix functions come into play.
What is the hand throttle connected to, and what is it's function?
Understand the physics of "Flow through a fixed orifice".
How high does the slide need to rise in order for the Main Jet to add it's function to the carb's operation? Why? What is the physics behind this?
What happens when you ride up a steep hill? Why?
What is the "Venturi" effect?
Dellorto Motorcycle Carburetor Tuning Guide
What is the "Bernoulli" effect?
What Is the Bernoulli Effect?
How do these two "effects" help make the carburetor function? Why?
What happens when you place a heavy load on the motor?
What happens if you forget to downshift the transmission, and the bike struggles to go?
What happens when you are steady cruising? Why?
What is that hole on the bottom of the slide for? What happens if I make it bigger? Smaller? Why?
What is the function of this spring inside the diaphragm chamber? What if it were stronger? Weaker? Why?
What happens to the functionality, pressurization and balance of all this if I remove the Airbox, and replace with tubular filters? Why?
What is needed to start a motor on a cold morning? Why?
What is happening at the various Throttle (1/4, 1/2, 3.4, WOT) openings? Why?
I list these various topics because you'll find endless - and at times mindless - internet debates about these individual subjects. Once you've spent some serious time at the ol' kitchen table studing, and "touchy / feeling" the carb and parts, you'll soon see how these functions are covered in the carb's design, and actually what a great little device it really is.
Anyway, this is how I learned, and how I tried to teach my two sons, and it seemed to work OK. There are likely better ways to learn, but at least it's a start.
Now, the trick is to provide clean, ultra filtered, and non-turbulent air to the carbs inlet.
Beware of the many Filter offerings out there - read the thread about Air Filters. Newbies often fall prey to the aftermarket filters that claim huge "Horsepower" gains. Almost always at the expense of good filtering.
If yours is a pure racebike, and you intend to "tear it down" every 500 hours or so - -a "Race" filter might be considered. If yours is to be ridden on the street, go for filtering ability over "air flow" every time.
If the brand or type of "Air Filter" is a huge differential to the performance of your bike... then suffice to say that yours is NOT really a "Performance" bike. Use what is practical, and focus on more important things.
In the end, I'm certainly no "expert", as I try to learn, and experiment with new and different things every day. There are ton's of guys out there with more knowledge than me, I hope!
(It would be a sad world otherwise!)
Anyway, try this study method if you like, and see if it helps. Let us know what ya' think!
Edited an hour later:
One last little tid-bit: Be VERY careful and selective around installing and using A/F gauges / indicators. Do a ton of research, and think a lot about...
Location of sensor bung - you want this to be as close to the exhaust valve exit as possible, yet be aware of temperature cautions. The closer you are to the exhaust exit, the more accurate the reading will be. These units measure the amount of 02 in the burnt charge. "Sniffers", as used on most Dyno's and at the EPA Test Facilities, are measuring other things, like Hydrogen, and CO2. Be aware of the "reversion" phenomina of exhausts (back and forth motion of the exhaust air) and how this activity will dilute the charge read if the sensor is located too near the silencer outlet, too far from the exhaust valve outlet, or in the "crossover" pipe. If you have an EFI bike, note where the manufacturer placed the sensors along the pipe. Much study, and trial and error, went into this final location selection.
Target A/F Ratio - 13.2 sounds impressive (More Power! I'm RICH!), but is it the ratio you want across the board? Why? Think about it for a while. What ratio would you want while cruising along at say 65 MPH on the highway? Why? When you learn about carbs as in the post above, think about what a WOT Dyno run displays and illustrates. Is this display realistic for everyday riding? Why not?
Digital or Analog - digitals tend to display rolling numbers, ever changing, which is annoying. An old skool analog dial can be buffered, and may be easier to read. Check 'em out.
Lastly, think about whether or not a given/chosen A/F ratio - for example the 13.2 ratio, is actually the best for the highest power, highest efficiency, highest burn rate for your bike? How do you know by looking at an A/F Gauge read-out? What is it actually telling you? What is it NOT telling you?
Yes, I agree that these gauges are useful, and fun to watch and mess with. On the other hand, there are a lot of questions as to overall accuracy, and cause/effect impact. there are also a lot of debates around best location, and best A/F ratio targeting.
A better overall indicator would be comparisons of before/after lap times, 1/4 mile E.T.s, top speed achieved, etc. Otherwise, what's the point? Also realise that CV style carbs are tuned by throttle position, not RPM, and not by running the bike at WOT. That said, ask again what the function of an A/F guage might be for a CV carbed bike.
Too many questions... eh?
Riide Safe!
Bob
Re: Carbs; Jetting; Etc. 
