What do the white widgets on top of the carbs do?
What are they?
Why no vaccum libes on the left nubs?
Gracias all!
they are the atmospheric vent tubes for the diaphragms inside the carbs sorta like one way check valves.
Is this how the diaphragms get their vaccum to lift up? Or do they get it from elsewhere?
@jfman, they get their vacuum from the vacuum port on the left side of the carb, the same vacuum port that opens the fuel petcock. Whether the valves get vacuum or not depends on the solenoid on the bottom of the carbs.
You can simply remove all that plumbing on the carbs because the valves are useless, at best they make no difference at all. You can test this yourself simply by unplugging the solenoid and ride around for a few days. You can follow the wires from the solenoid up through the frame and you can unplug the little white connector which is easier to get to than unplugging the solenoid directly.
http://gstwins.com/gsboard/index.php?topic=72511.msg873220#msg873220
http://gstwins.com/gsboard/index.php?topic=57529.0
TL;DR:
It lets atmospheric in to dampen the raising action, controlled by the lower vacuum switch.
The lower switch is controlled by the ECU which is probably fed data by the TPS. The vacuum damper way off by itself is probably to help smooth out the natural pulse-action of the vacuum lines (perhaps similar to a hammer-arrester in a water line, or a capacitor in an electrical system) since that pulsing would cause that diaphragm/needle to flutter.
Since all this stuff showed up together it's all likely related, and there have been numerous accounts of people stripping all those vacuum lines out and unplugging the TPS and having their bikes run fine. Not sure if that requires carb tuning->balancing, but possible.
-mox