The only thing less complicated than replacing a battery, it putting air in tires. UNTIL YOU TRY TO RESET Throttle Position Sensor.
Sure, if you work on BMW motorcycles for a living or have replaced many batteries in K1200GT's, it is a no brainer. BUT, if you never did it before and you try to follow instructions in the Clymer Manual, you might have problems like I did.
According to Clymer BMW K1200RS, GT & LT 1998-2005, page 267,
"Substep f must be performed to maintain the safe and functional operation of the motorcycle. If any fault codes were set before the battery was disconnected, the will be reset as soon as the motorcycle is ridden as short distance.
"f. Do not start the engine. Turn the ignition switch on and then fully open the throttle once or twice to allow the Motronic control unit to register the throttle-valve positions."
I tried this many, many times and it did not work. The bike would idle ok once it started up. But once the engine rpms were increased and then brought back to what was to be idle the engine would stall and die. Over and over and over again.
Then, I looked up my problem on the internet and found this on k-bikes.com:
"BTW- Since you disconnected the battery, don't forget to re-set your fuel delivery. Kill switch on, key on, (DO NOT START THE BIKE) roll the throttle full open three times then turn the key off. You're now re-set."
Note that there is nothing about the kill switch in the Clymer instructions and nothing about turning the key off. This may be already known by some, or most, but it was not stated in Clymer and since this was my first battery replacement on the K1200GT, it was not at all helpful. Why? I followed the instructions in Clymer to the letter.
Lesson learned, Clymer assumes you know what you are doing, you have experience.
Here is what to do after replacing the battery,
1) Turn the ignition key on
2) Turn the kill switch to the on position
3) DO NOT START THE ENGINE
4) Roll the throttle full open, hold open for 2 or 3 seconds.
5) Roll the throttle off.
6) Repeat steps (4) and (5) three times
5) Turn the key off.
You're now re-set.