Here is what I've got so far...
Some bikes have a problem with idle quality after they get warm, this seems worse after a lot of stop and go driving in hot weather. The bike's idle may drop very low and go up and down, and some will even die and the bike needs to be restarted. Some Rocket Captains have taken their bikes into the dealer and most times the dealer reprograms the bike which helps for only a few minutes/miles and the problem comes right back. Some have had the idle stepper motor replaced which doesn't seem to help either.
At this point in time I haven't been able to find the root cause of this problem. Since this happens in both bone stock bikes and modified bikes I think we can rule out aftermarket engine modifications as the cause. Not all bikes exhibit this problem (mine doesn't) which makes me believe it may be more of an adjustment issue than a mechanical or electrical failure. This is further supported by the fact that almost all of these bikes run OK until they get very warm (complete heat soak). Electrical components like stepper motors and temp sensors usually fail completely, they don't work for awhile and then fail and then come back. I think that probably the cause of this is the fuel and ignition map letting the idle drop too far.
My solution at this time is to set up the base idle mechanically as opposed to using the Triumph scanner to set the idle. I think the fuel map is corrupt and using the scanner won't solve the problem.
Keep in mind that I worked on this on a day when the outside temp was 10 F (about - 12 C) and that my own bike doesn't exhibit this problem, so for those of you who want to try this keep in mind everything can be set back to the original specs if it fails to fix your symptoms. Also please understand that Triumph won't do this under warranty for you, it is not a Triumph Technical Service Bulletin. Also if you do this to your bike you do so at your own risk....
HOW TO SET THE BASE IDLE
Please read this completely before starting any work. I would say that the skill level required to perform this adjustment would be "Advanced".
Some of the tools required are:
A quality DVOM
The Triumph service manual
An OBD II scanner
"T" pins to back probe wiring connectors
A socket set that includes 8 and 10 mm sockets
7 mm wrench
A 2.5 mm allen wrench (or key)
A T 25 torx bit
A phillips screwdriver
4 and 5 mm allen wrenches
There is a small adjustable throttle stop that we are going to adjust so the idle doesn't drop off into oblivion.
Make sure your battery is fully charged, it should be at 12.4 volts or greater with the bike not running. If it isn't, charge the battery, if that won't bring it up... replace the battery.
Go out and ride the bike, get it warm..
Remove the seat.
Remove the chrome bearclaw and lift the gas tank and place it on the propwand.
Take the 2 8mm bolts out of the coolant overflow reservoir and use some string to tie it up to the handlebars up and away from the front of the throttle bodies. Do not disconnect the rubber hose going to the radiator cap. There is an overflow hose in the top of the reservoir that you must pull out, just let it lay on top of the intake plenum.
At the rear of the throttle bodies and to the front of the frame tube there is a small triangular cover or garnish plate that has two torx screws in it, remove this cover.
Locate the primary throttle potentiometer at the rear of the throttle bodies. It has a short wiring harness with three wires under a black protective sheath that runs up to a connector. On the sensor side of this connector you will find a solid yellow wire, backpin this yellow wire with a "T" pin.
Click here for huge pic
Hook your positive lead of your DVOM to this pin.. hook the negative lead to a good metal ground (not the battery negative post).
On page 11.127 of the Triumph it says to use the Triumph scanner to "drive the primary throttle to the fully closed position" We don't have the Triumph scanner so we have to do this manually. Locate the stepper motor at the front of the throttle bodies and unplug the connector that plugs into it. It has a small tab you have to press to do this... a small pocket screwdriver is helpful. Now remove the two phillips screws that hold the stepper motor to the throttle assembly. Just let the stepper motor hang there, you do not have to remove the small cable. THIS WILL throw a check engine light later.. don't worry about it at this time.
Click here for huge pic
Pull out the fuse for the headlights. Turn on the ignition but don't try to start the bike. Blip the throttle a few times to make sure the throttle is fully released. Look at the reading on your DVOM.. it should be .6 volts +/- .02 volts. If it isn't.. you had a problem you didn't even know about :-D We will fix this later... Turn the ignition off.
Go to the front of the throttle bodies and you will find the throttle wheel that the two throttle cables attach to. If you study this assembly you will see a small set screw that is locked with a nut that has yellow paint on it. Take your 7mm wrench and break this locknut loose.
Click here for huge pic
Back this locknut off a few turns and insert the 2.5 mm allen wrench into the setscrew. You can get to it easily by going under the secondary throttle potentiometer. DO NOT loosen or remove the secondary throttle potentiometer. Hook the OBD II scanner up to the bike. Put the headlamp fuse back in. I would lower the tank at this point. Start the bike and let it run until the cooling fans kick on. After the fan turns off screw the setscrew in until you have about a 850 RPM idle displayed on the OBD II scanner. If you don't have a scanner you will have to use the inaccurate tach on the bike. I set mine at 850 RPM's, you have to decide if this is too high or low for your tastes. I wouldn't go below 750 RPM's... the idle quality seems to get very weak below 800 RPM's and that is what we are trying to fix. At 850 RPM's it really is healthy... it thumps in your chest.. (I have the cat bypass and Mad Dogs). Once you are set where you like it tighten the lock nut and see if the idle stayed where you wanted it, if not, reset it. FYI.. I turned my setscrew in about 3 turns.
Now we have to reset the primary throttle potentiometer which is at the rear of the throttle bodies. Turn the bike off, pull out the headlamp fuse. Loosen the Torx screw on the primary throttle potentiometer. Turn the ignition on but don't start the bike. Turn the primary throttle potentiometer until you get a reading of .6 volts +/- .02. Blip the throttle to make sure the throttle is completely closed and you can repeat the .6 volt reading. Tighten the Torx screw and make sure you still have .6 volts
Remove the "T" pin from the wiring harness.
Re install the stepper motor and plug in the stepper motor connector. You will have a OBD II error code 505 for "Idle circuit malfunction", clear the code at this time. If you don't have a scanner refer to page 11.27 of the shop manual which states the light will go out after three running cycles and clear itself completely after 40. A running cycle usually means going from cold to hot, so it may take a few days for the light to go out.
Turn the bike off, reinstall the headlight fuse. Reinstall everything else (The coolant bottle, the bear claw, the garnish piece, secure the gas tank, reinstall the seat.)
Let the bike cool completely (overnight). Perform the 12 minute tune.
Go out and ride it and see if the idle is where you want it, if not repeat the above as needed. (I never said it would be easy :-D )