My bike has been stalling a few seconds after cold startup. The service manual constantly refers to the importance of the Idle Air Control Valve (IACV), so I decided to replace it and see what happens. Turns out...this didn't solve the problem.
: turns out, it did
solve the problem! Cold start idles at 2000 RPM, drops back to 1750 RPM, then drops to steady hot idle at 1500 RPM...just like it did when new. When it wasn't working, it would cold start at 1500 RPM and then stall.
I can report that it's not a difficult job to replace the IACV.
The part being replaced is located on the Throttle Body, shown in this diagram as assembly #10
It's necessary to first remove the seats, side fairings, the fuel tank side covers, and the fuel tank front cover. Then, unbolt the fuel tank at the front and lift it using a 5" / 125mm prop rod. I found it necessary to remove the overflow hose on the left side of the tank to lift the tank up enough to gain access to the IACV.
The IACV is on the right side of the bike, under this silver retaining plate secured by two screws. Before loosening the screws, disconnect the connector seen right above the black dot on the silver retaining plate.
To remove the screws, a T20 Torx security bit (with a hole in tip to provide clearance for the security pin) is needed.
IACV with retaining plate and connector removed.
New IACV "Valve Set", Honda P/N 16430-KYJ-901 (includes valve + O-ring). It's a stepper motor. The black plastic rotor seen at the bottom needs to be gently spun down the shaft until it lightly makes contact with the motor. Before installation, the slot in the shaft needs to line up with the dot on the silver motor casing (or, the slot needs to be located ~160 degrees counter-clockwise (anti-clockwise) from the connector when looking down from the top).
The slot in the black plastic rotor must be aligned with the brass pin seen here on the left inner wall of the IACV port.
Add blue Loctite to retaining screws and re-install retaining plate over IACV. The service manual says 18 in-lb (2 N m). My smallest torque wrench only goes down to 20 in-lb, so I just carefully snugged the screw "tight enough". Be careful, though, the IACV port is cast aluminum.