System Case Upgrades

"Rekeying" K Bike Locks

BMW K bikes have a variety of locks. Many times a K bike will have more than one key. A common example is that the side cases have been purchased separately and use a different key than the ignition key. Fortunately, for many of the locks, the lock cores can be removed and modified to work with a particular key.

The basic procedure is pretty simple: remove the lock core, insert the key that you want to use and file down the tumblers (a.k.a. wafers) sticking out.

Here's a K bike lock core. (from a system case lock) They are all basically the same with respect to how they work. They have six metal slats with tiny springs in them. Since we're dealing with locks, I'll call them the "tumblers." The last tumbler is what holds the lock core in the lock. I call it the retainer tang.

What you do to make the lock work with a particular key is to insert your key and then file down (I use a Dremel grinding wheel) anything that sticks out. Here's a lock core from a 35L top case:

To rekey a lock core, insert the "new" key and then file down anything thing sticking out - except for the very last one as that is what holds the lock core in place in the lock:

The table below lists the various locks on K bikes and has some comments on rekeying each.

Lock	Rekeyable	Comments
2V Ignition	Y	A little tricky because you need to pop the metal cap off of the top along with the springed "door" and then reinstall them but possible. For this reason, I usually modify the bike's other lock cores to match the ignition key.
4V Ignition	?	Never tried but I imagine it's possible.
2V Steering Lock	?	Never tried. Don't know.
System or City Case	Y	See below.
22L Top Case	Y	See below.
35L Top Case	Y	See below.
Gas Cap	Y	See below.
Seat/Helmet Lock	Y	See below.
Low Seat Lock	Y	See below.
RT/LT Radio & Bucket Covers	N	I haven't put a ton of effort into it but I've never figured out how to access the lock tumblers on these. For this reason, if one of your covers ever gets broken don't just throw it away without first saving the lock from it.

System Case or City Case

Turn the key to the open position, open the lock, turn the key to the locked position and then use a 3mm or 4mm Allen wrench at the back of the lock core to depress the retainer tang. Then slowly wiggle the lock core out:

22 Liter Top Case

I don't have a picture handy but first remove the lock from the case by removing the large plastic hex nut inside that holds the lock in place. You'll see a small hole in the side of the lock that is located above the retainer tang. Turn the key so it's facing that and then insert a sewing needle, dental pick or other slim metal object into that hole to depress the retainer tang. Then wiggle the lock core out.

35 Liter Top Case

There are some Phillips screws the hold the handle and lock assembly on the inside of the back of the case.

Gas Cap

I recommend doing this off of the bike so parts don't fall into the tank. The gas cap is removed by unscrewing the four countersunk Phillips screws you see around the perimeter when the gas cap is open. Since they are mounted in aluminum, the dissimilar metals can cause corrosion in the threads. Therefore you need to be careful removing them or you can strip the heads of the Phillips screws. First clean out the heads with a dental pick or something so that you can get a Phillips screwdriver all of the way in. Then, using your best fitting/best quality Phillips screwdriver apply a lot of downward pressure while initially turning the screw to break it free.

Once you have the gas cap off of the bike remove the three Phillips screws that hold the lock assembly to the gas cap.

Then use a screwdriver or whatever to depress the retainer tang and remove the lock core:

Putting the gas cap back together can be a little tricky installing the cup and return spring properly. Start by putting the return spring in with the part sticking out at a right angle positioned in it's groove in the lock housing:

Then put the "cup" on so that the groove on the bottom of it sits on the center straight part of the spring:

Applying constant downward pressure, slowly turn the cup counterclockwise until you feel it drop into place:

Then carefully reattach the assembly to the gas cap with the three Phillips screws.

Seat Lock

Remove the seat lock from the frame by unscrewing the two 8mm nuts on the back of it and the two small Phillips screws from the front. Use some small screwdrivers to break the face plate off of the rear housing. It will look like this:

(Hopefully your seat lock hook isn't busted off like this one. It's just an old one I'm using for demo purposes here.)

Pop the latching bars out of their pivot and then you can remove the lock. Use a dental pick or sewing needle to depress the retainer tang and remove the lock core:

Once you've modified the lock core, glue it back together with some epoxy or JB Weld around the outer edge. One nice thing about the design of the seat lock is that the two bolts at the bottom that attach it to the frame help hold it together.

Low Seat Lock

Remove the machine screw on the back of the lock. Insert the key and pull inner assembly out. The lock core can be removed by depreesing the reatiner tang.