SEAT REMOVAL:1) Remove the right side(a.k.a. battery) cover:
K100, K100RS, K100RT, K100LT, K75RT: Pull the top front corner of the side cover out of the large rubber grommet hanging down from the gas tank. Drop it down so the hook clears the rubber piece on the tang sticking out from the frame and then pull the cover forward towards the front of the bike to free the post at the rear corner.
K75, K75C, K75S: Pull the cover down until the two hooks that fasten it to the seam of the gas tank are clear and then rotate the top of the cover outwards. Then pull the forward towards the front of the bike to free the post at the rear corner.
2) Remove the C clip from the right front hinge. There may or may not be a clip there. It's not really necessary.
3) Unlock the seat by inserting the key and turning it all of the way counter-clockwise.
4) Push the lock in to unlatch the seat and rotate the left side of the seat upwards.
5) Remove the C clip from the top of the hinge that holds the seat open.
6) Using some needlenose pliers, remove the C clip from the rear pivot pin under the right rear corner of the seat.
7) Remove the pivot pin.
8.) Standing on the right side of the bike, grab the front and rear of the seat and rock it a little to slide it off of the forward right pivot. When removing the seat, keep an eye on the rear hinge arm at the rear of the seat to avoid scratching the tail cowl's paint.
9) Installation of the seat is the reverse. (When closing the seat always make sure that it latches completely. Otherwise the latching bar on the seat will ride on the top of the latching hook in the lock and eventually wear through it and break it.)
BATTERY REMOVAL:1) Remove the black plastic pin on the right side of the L-Jetronic (fuel injection control unit) by pulling up on it with some pliers.
2) Remove the left side cover.
3) Remove the L-Jetronic mud cover. (Not all of bikes have this part. BMW cheaped out in later year models.)
4) Pull the L-Jetronic out of the bottom of the tool box from the left side.
5) Pull the tool box back and up to remove it. (Don't lose any of the four rubber bumpers that it mounts on.)
6) Remove the two long Philips machine screws that secure the battery hold-down plate.
7) Disconnect the battery. Disconnect the ground (black wire) terminal first. That way if your tools hit the frame when disconnecting the positive (red wire) terminal it will not cause a short.
8.) The battery can now be lifted up out of the frame. It's a tight fit if you have a full-sized battery.
9) Battery installation is the reverse.