Anyone know what this might be for?

[Zeus36]

Uh, you draw twice the air (two venturi) at those lower RPMs with Vboost open, too. I installed T-Boost on my 94 and loved it. And I currently have an On/Off Vboost switch. I like having the flexibility. Have you ever tried it?

Yes, I did some experimentation, but was not able to tell much difference between the settings.

 

[DRWard]

I traced the black wire back to the coil,

Just another spectulation, I know some folks would cycle the Ign switch and unplug the vboost plug right when the servo motor opened the vboost. Leaving it in open all the time. Maybe this is a switch that does the same thing. Basically breaking the circuit during the vboost cycle at ign on. Try turning on the ign, and while the vboost servo cycles, flip the switch to hear if the servo motor stops before completing the cycle. Not sure if a switch could do this with just one wire, but just a thought.

 

[Fire-medic]

Simply unplugging the round V-Boost plug under the left scoop when they open sure makes it easier to synch the carbs than eliminating the V-Boost like the Stage 7 Dynojet instructions say. To synch, just re-plug your stepper motor plug for the V-Boost.

 

[Dan Lee]

Add-on. I'd think a fan on/off switch would be on the right side, as desert_max said, because that's where the thermocouple is.

When you turn-on the ignition, but before you start the bike, you should usually hear two sounds:
1] the tick-tick-tick of the fuel pump, for several seconds, it quickly slows, and stops.

2] the V-Boost stepper-motor, a constant whirrrr, a brief stop, then whirrrr-again, and stop, no sound.

If you don't hear these two sounds, 1] your fuel system is already pressurized, and 2] something's wrong with the V-Boost motor

If you kneel-by the left scoop, ear next-to the scoop/steering head, and reach-across the bike to turn on the ignition, you may better be-able to hear the V-Boost motor opening, then closing the V-Boost butterflies.

So I tested this switch today in town, holy crap, v-boost at 3000 rpm is wicked fast. Ended up doing 100 miles on the bike today, switched it back to normal 6000 rpm, thought I would let you know