Not sure how I missed this thread.
set it to the correct level in the middle of the carb (inline with the main jet).
correct
" It's not rocket science and it's not a MotoGP motor. You can make yourself crazy worrying about differences that make no difference on a street bike.
Fuel level makes some difference. When the fuel is set to .0XX", I always reference to the BODY..why?
the main needle jet is connected to the body (via the jet holder) and is the primary distribution for above idle fuel. The needle jet length is about 1/4" long however the top of the needle/jet .107 interface is 3/16" below the carb body. That is where the fuel level belongs...+ or -
Within reason , it probably does not matter where the float levels are, as long as they are the same in both carburettors.
The idle circuit is much less affected by fuel level. Idling means the slide is closed and there is quite a high vacuum (though pulsating and sharing by the balance tube) and the idle fuel is filling the front to back passage and ready to pass through the jet into the mixing chamber (under the round blanking disc). In fact there would be too much fuel unless you open the air bleed/idle mixture adjust and let additional air in.
3. Pilot circuit mixing chamber (coloured in Yellow) – this is where the metered amount of gas is mixed with the metered amount of air and travels up into the engine through two tiny holes (mildly correct IMHO inadequate description )
Rather than to "disagree" with bushman #3:
http://www.jba.bc.ca/Bushmans Carb Tuning.html
Instead let me expand the description to my understanding and extensive carb work since the mid 1970's.
The two tiny holes are:
1A. top hole is before the throttle slide and therefore @ atmosphere. It is an air supply portion during closed throttle idle that mitigates the vacuum to the fuel circuit. (coming from hole 2)
1B. top hole only acts later as a second (fuel/air mix) mix distribution once the slide starts to raise and atmosphere is replace by vacuum applied to this transition port.
This characterstic is entirely the same for throttle plate carbs as plate swings by exposing the additional holes to vacuum. Remember there is a partial vacuum all the way to the front of the slide due to the cutaway.
2/bottom hole is after the engine side of the throttle slide, and is where the 2nd air fuel mix enters the air stream.The air bleed screw is now the main air to the "mix".
However by design this circuit is now a minor contributor to air/fuel mix running the engine.
ROFLMAO
I'll agree the engine can run with a sloppy carb set up... ie 30 all the way to 55mpg.... start easy start hard