Fuel injection - idle control

Just a general tecchy question. I'm a (reasonably) full bottle on car fuel inection systems using a stand-alone system on the (stalled) track car project, but I was wondering:
How do fuel injected bikes manage idle RPM?
[i]Cars have a stepper-motor controlled valve that provides a "leak" into the intake plenum. The throttle butterfly closes completely. This means the ECU controls fast idle on cold starts, bumps the idle up just before the aircon compressor kicks in etc etc[i/]
How do bikes do this with the 4 throttle bodies? How is balance maintained (ie like carb balancing to smooth the idle)?

.. grab a genuine manual and have a read

in basic terms a number of throttle position sensors
and air pressure sensors (4) control idle and off-idle fuelling