Okay, so I finally figured this out. My problem was that THE BOOK IS WRONG. It says to first sync the throttle bodies with the air screws (without caring how many turns in or out these screws are), then, once all 3 throttle bodies are synced, turn the idle screw until you get 950 rpm. Book = Wrong. Themason = Right.
I derived my own proper procedure from the work I used to do on Audi KE Jetronic fuel injection. The "idle screw" (this is the wrong name for this) is actually intended to act as a range limiter, or "stop" so that the throttle plates don't make contact with the throttle bores. If they close too far, they can gouge the bores over time, which can ultimately have a negative impact on performance and ruin the assembly. This is supposed to be a static setting that is only performed once at the factory, which is why this screw originally had paint on it. If, however, you disturb this setting, you need to reset it before you do anything else.Ty's Procedure for Resetting the Throttle Plates Stop Screw
1) Slacken or disconnect the throttle cable and fast idle cable (aka "choke" cable, which is another inaccurate name)
2) Loosen the 2 TPS mount screws. The TPS should move freely. (I removed mine just to be sure.)
3) Unscrew the "throttle plate stop screw" (aka "idle screw" - sigh) until a gap exists between the end of the screw and the stop plate.
4) Tighten the screw until it just makes contact with the stop plate.
5) Further tighten the screw 1/4 turn. (This is just enough to keep the throttles from touching the bores, but not introduce any significant effect on the idle setting).
6) Re-paint the screw (that is, if you're a perfectionist like me!
A dab of light blue touch-up paint is preferred, but anything that's not screw colored will do nicely, ha ha).
7) With the TPS loosely mounted, lightly rotate it clockwise (looking at it from the rear of the bike) until you just hear the click and lock it down with the 2 mount screws. Verify the clicks by manually moving the throttle lever up and down.
8) Re-attach and/or re-adjust the throttle and fast idle cables.Ty's Procedure for Setting the Idle
1) Confirm the throttle and fast idle cables are adjusted properly.
2) Confirm the TPS is adjusted properly by opening and closing the throttles and listening for the click when the throttle is just beginning to open, and clicks again just as the throttles completely close.
3) Install a sync gauge on all 3 sync ports. (Note: Be sure and use a tee fitting for #3 body to tap inline with the regulator vacuum hose. This is especially important if you set the CO after setting the idle because it will affect this setting if you don't.)
4) Lightly tighten all 3 air bleed screw until they softly seat and bottom out.
5) Unscrew all 3 air bleed screws 3/4 to 1 full turn each.
4) Start the bike and warm it up until the cooling fan begins to cycle.
5) Perform an initial sync by turning the #1 and #3 bleed screws so those throttle bodies sync with #2
6) If the idle is above 950 rpm, try tightening the air bleed screws about 1/8 turn and re-sync. Conversely, if the idle is below 950 rpm, turn the air bleeds in the other direction.
7) After stair-stepping a bit, using smaller and smaller turns on the air bleeds, you'll get 950 rpm with synced throttle bodies.Ty's Procedure for Setting the CO
(Note: Setting the CO % is the absolute last thing you do during a tune-up. It assumes that valves, ignition timing, throttle body sync and idle speed are all correct. Confirm you have good spark plugs and a clean air filter. Confirm no intake or exhaust leaks. Confirm fresh fuel and proper fuel pressure.)
1) Confirm the throttle bodies are set up correctly as described above.
2) Confirm the throttle bodies are sync'd the idle is set to 950 rpm as described above.
3) Warm up the bike until the cooling fan cycles on and off.
4) Insert an exhaust gas analyser probe into the end of the exhaust pipe
5) Once the readings stabilize, read the CO %. It should be at or very near 2.0% (+/- 0.5%). If it is, then you're done. If not, continue.
6) Remove the service plug from the top of the air box at the front right side. (You may need to slide the gas tank back a little bit to access this.)
7) Insert a 5mm hex key into the hole so it fully seats into the mixture adjustment valve
8) If the reading is above 2.0%, turn the valve clockwise. If below, turn counter-clockwise (looking at it from the top of the air box)
Note 1: Turning this valve has an immediate effect, but may take about 10 to 15 seconds for the exhaust gas analyser readings to settle down, so be patient and wait for the readings to stabilize before you turn it again.
Note 2: If the cooling fan turns on, wait for it to turn off and take the readings. The extra load from the alternator when it turns on makes the readings change.
Thank you all for your replies, especially Themason, who pointed me in the right direction! Please let me know if I need to amend my procedures. This all worked very well for me. My bike has a very smooth idle now, plus strong, smooth and snappy acceleration, just like a new one probably did!