This is based on the combined wisdom of dshealy and SilverBuffalo on the BMWLT.com Website. The threads are http://www.bmwlt.com/forums/showthread.php?t=29394 and http://www.bmwlt.net/ubbthreads/showthreaded.php?Cat=&Board=K1200LT&Number=35118
First, you have to special order a set of #6240 1" universal grips, BUT with 2 right hand grips! I ordered them straight from Kuryakyn, but first time they sent mt two LEFT hand grips instead. The left hand grips are 1" inside diameter, the right ones 1 1/8".
You can also order the part number above. The left grip approximately 1" diameter (part number 606236L) fits the heated grip sleave snugly,
I called Kuryakin and they shipped me a pair of them for $75.
Next, CAREFULLY cut off the stock rubber grips, being careful not to nick the heater wires. This can be done on the bike, you do not have to remove the grips.
Next I measured the length of the Kuryakyn grips and the heated grip sleeve and made a spacer (5/8") to take up the gap at the end. I filled the gap at the end of the grips with a couple of o-rings, sprayed some hairspray inside the grips and on the (heated) sleeve and whacked the grip with the butt of my hand and slid it home
Sounds a little troublesome, but if you take your time getting everything just the way you want it before the glueing process, all will be well. Once you start the glueing though, there is no going back! After I installed them and rode with them for a couple of days, I thought that I would miss the throttle rocker that I use on long trips when the cruise control cannot be used. Kuryakyn makes a metal "throttle boss" that is clamped on the end under the end cap. I purchased this and installed it, seen in the pictures I posted earlier. works great. A little trouble to go too, but I am glad I installed them. I have wanted larger diameter grips since I got the bike, and I like these even better than the "cruiser" grips on some LTs.
It takes a while for them to warm up but they do so nicely, I also noticed that they stay warm for quite a while after you turn them off. There is a lot more thermal mass in the metal, that is why they take longer to cool off.
Last photo is from Big Ed's post in the first thread listed above. The other pics are from Silverbuffalo and dShealy