After much researching I decided to replace the OEM AM/FM Cassette Deck with something a little more modern: A
Pioneer DEH-P7600MP MP3 CD head unit and a
Pioneer CD-MR70 Marine RemoteI selected this combination because:
1) It had a waterproof remote that I could mount on the handlebars.
2) The remote is hardwired so there's no batteries to mess with.
3) The head unit plays MP3 CDs so, at a 96 bit rate, I can get several hundred songs on a single CD-R.
4) The head unit also has a high-pass crossover so it can be setup to not play lower frequencies - which sound like crap on 3.5/4 inch speakers and it also helps keep the speakers from blowing.
First you need to remove the old radio. There are three clips that hold the metal radio faceplate in the left "bucket." The secret is to stick a small screwdriver or ice pick in these holes to pop the clips. Then the whole unit can be removed with the faceplate.
Then you need to remove the radio from it's DIN mount using standard head unit removal tools:
The head unit install was pretty simple. If you've ever installed a car stereo then it's pretty much identical to that. Even if you haven't but are moderately competent at wiring then it comes with an installation quide (attached below in PDF format) that shows you how to wire it up. I've also attached a PDF of the wiring diagram for a K1100LT radio so that should help you figure out which wires do what.
I did need to take a Dremel cutting wheel to the rear of the BMW mounting bracket to allow everything to be plugged into the back of the new head unit but that was pretty straightforward too.
The next challenge was to take a marine remote deisgned to fit into a 2" hole and make that work on the left handlebar.
Here's the CDMR70 out of the box:
Remove the screws as shown to take off the mounting bevel and take it apart:
It looks like this when taken apart:
Use a Dremel or whatever to cut off the 2" cylinder on the back and the tabs for the silver mounting bevel which isn't needed:
To make for a more durable connection, I actually resoldered three new wires long enough to be wired to the head unit and then connected them to a standard stereo jack but you could also use the wiring that comes with the remote.
I had a metal shop build me a custom mounting bracket for my LT but on another bike I installed one on I was able to make my own mounting bracket using Ram Mount components:
