Customizing your stock K1200LT seat

By Will Card
November 2001

The following instructions were used successfully to remodel the stock seat on a 2001 BMW K1200LTS for greater rider comfort. This is not the heated version of the seat and I strongly recommend you not try modifying the heated seat. Few people enjoy sitting on logs for long periods of time but that's what they get using a stock LT seat. The following instructions provide an alternative to expensive custom seats. However, use of these instructions implies no warranties nor guarantees. Proceed at your own risk.

Please read through these instructions completely before starting work.

Armed with confidence after reading another rider's instructions on how he modified his stock seat, I took the plunge and modified my own 2001 BMW K1200LT.

seat-mods1.jpg

Thought others might want to consider doing so as well so here are the details.

The objective is to trim the top of the seat's foam core from a rounded/concave log shape to a flatter one, like this (you're looking at the seat from the front).

seat-mods2.jpg

Please excuse the hokey graphics but, hey, what do you expect from something that's hand-drawn!!! <wink>

List of Materials:
  1. Rivet gun (the type with the "nose" sticking out rather than the flush one; see graphic below).
  2. seat-mods3.jpg

  3. 1/8-inch (3mm) Rivets. I used Arrow E-Z Pull aluminum short rivets. Bought one large box of 50, I believe. Used about 30.
  4. 1/8-inch Rivet Washers (or any washer that will fit). I used aluminum Arrow E-Z Pull Back-up Washers. Bought two boxes of about 30 each, as I recall. Used less than one box. I had some left over.
  5. Contact cement. Any kind.
  6. Long sharp knife, preferably an electric knife like you'd use to cut a turkey. Or you might use a heated knife but they're pricey (see http://www.demandproducts.com/hotknife.php.
  7. Electric drill with a sharp 1/8-inch drill bit and sanding disk.
  8. Chalk.
  9. Awl or leather punch.
Process:
  1. Board your Beemer and sit on the seat.
  2. Mark with chalk on the seat the outline of your legs so you'll know where to trim the foam down a bit. That is, although your intent is to cut off the log-shaped "top" of the seat, you'll also want to trim off a little on the sides of the seat where your legs are so there's nothing pressing against the legs with the lower seat position. The chalk can be easily cleaned off of the seat, by the way.
  3. Remove the seat from the bike by extracting the four silver Allen head bolts attaching the seat to the frame arm protruding from under the oddments box lid.
  4. Turn the seat over so the bottom is facing up to protect the leather from abrasion.
  5. Using the 1/8" drill bit and electric drill (duh!!), drill out all of the existing black rivets on the underside of the seat from the front around to the split in the leather about 2/3 of the way to the rear (about 15 rivets on each side). The heads of the rivets will typically get caught on the drill bit. The shaft of the rivets will be forced into the seat foam.
  6. Now, keeping the bottom of the seat up, carefully pull the leather from the seat pan (the hard plastic base). It's adhered to the pan using contact cement but the leather will readily pull off if you pull on it carefully. The leather will tend to return to its original shape and re-stick to the pan so you'll need to do some "juggling" to get the leather off but it's easy to do.
  7. Turn the seat back over (so the bottom is facing down) and peel the leather back from the foam and lay it over the back-rest portion so it's out of the way. You can stretch it a little but be careful not to do so too much.
  8. At this point you'll be able to see most of the old rivet shafts imbedded in the foam. Just press the foam downwards toward the seat pan and the rivet shaft will pop up so you can grab it. In a few cases, you might need to dig a little. A pair of needle-nose pliers helps.
  9. By laying the leather seat cover back over the foam, you'll be able to see where you marked it with chalk for your legs. Flip the seat cover back over the back-rest. Using the sanding disk installed in the drill and holding the drill at right angles to the seat (sideways), sand off about a quarter inch of the seat pan across the areas on both sides where your legs will go.
  10. Trim up the area you sanded to remove burrs and melted plastic (the sanding will melt the plastic seat pan). You might just be able to break off the excess/melted plastic but be sure to wait till it's cooled!
  11. seat-mods4.jpg

  12. With the seat cover pulled back over the back-rest and the seat placed flat on the ground, top-up, you are ready to perform surgery. Using the electric knife (or whatever you're going to work with), carefully cut away the foam from about four inches back from the front tip of the seat to a point roughly vertical with the back-rest. (Side note: I actually cut mine back underneath the back-rest till I could see the "spring" cross-ties that support the seat pan but you need not go that far. In fact, it's probably better that you don't.) I used an electric knife with about an eight-inch blade. Thus, because of the width of the saddle, I had to make two parallel horizontal cuts - one on the right half of the seat and the other on the left.
  13. seat-mods5.jpg

    Be sure to cut with a downward angle, as shown above. If you don't, you won't be able to take off enough to make much difference and you won't leave an open area for your tail bone, which is crucial for comfortable long-distance riding.

  14. Notice the dotted lines in the graphic to the left above and the side wedges in the graphic to the right above. They represent the additional cuts that you'll need to make to round off the sides of the seat after your horizontal cuts. This will allow space for your legs. The cut-away area on the bottom of the right-hand graphic represents where you sanded off the edge of the seat pan. You'll want to cut away a small amount of foam there as well.
  15. When all the cuts have been made, you'll want to invest a little time trying to even out flat areas and round the edges. The leather seat cover is very thin so it shows bumps and ridges. When I reassembled my seat, I was chagrined at how...um...home-made I thought it looked yet everyone I've shown it to felt it looked fine and didn't notice the bumpiness that I did. The individual who remodeled his seat and from whom I drew my inspiration used a disk sander to smooth the foam. Not having one, I tried the drill-based disk sander (used above to reduce the seat pan edges) but it didn't work well. I ended up doing all my fine-tuning using the electric knife.
  16. Once the foam is as good as you can get it, pull the leather seat cover back down into position over the foam, flip the seat over so it's right-side-up, and pull the cover tight over the foam. See if you need to do any more fine-tuning. If not, flip the seat over so it is bottom-up once again.
  17. Starting on one side and then alternating from one side to the other, using either an awl or a leather punch, stretch the leather tight over the foam equally on both sides (you should see about the same amount of excess leather on both sides under the seat), hold the one side in position and then locate the existing rivet hole in the seat pan edge and punch a hole through the leather cover for the new rivet. (The pre-existing rivet holes will be too far to the inside after cutting the foam to be able to re-use them.) With the hole punched, using the rivet gun, install a rivet in the new hole through the leather and the seat pan. Be sure to get it through both the leather skin and the plastic seat pan! I found it made things simpler if I just left the awl in the hole so it kept the skin in place till I had the rivet gun poised over the hole. Then I'd remove the awl - while keeping the skin stretched taught so the new hole remained over the existing hole in the seat pan - and insert the rivet. Remember to insert the rivet washers along with the rivets for a secure connection.
  18. Here's the bottom view of the finished job. You can clearly see the old black rivets along the "top" and the new silver-colored rivets along the sides. The new ones begin to the right of the large white round label on the right upper portion of the seat pan. You can also see, in that same area, the seam in the seat cover that marks where I stopped drilling out the old rivets.

    seat-mods6.jpg

  19. Once you've completed the riveting, you can use the contact cement to secure the areas of the leather skin that aren't held close to the seat pan. I found that I only needed it in the area where the seat cover separated (was stitched together) at the widest part of the seat.
  20. You can now trim the excess leather (where the original rivet holes were) if you like. I didn't bother doing so since no one would see it and it didn't get in the way.

Here are photos showing how flat my finished seat now is. I placed the straight-edge on the seat in two positions (one slightly forward of the other) to demonstrate the flattened area of the previously-logged-shaped seat.

seat-mods7.jpg seat-mods8.jpg

The following photo demonstrates the removal of a small amount of the edges of the seat pan where my legs go. I marked the general area with the straight-edge. Look just below the straight-edge and you can make out how the seat now indents slightly (just where the seat greets the Tupperware side cover and just above the seam in the Tupperware).

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This completes the instructions on modifying the K1200LT stock seat. I just got through riding for about eight hours with about three stops where I dismounted the bike. Other than that, I was in the saddle the entire time. After about four to five hours, I had to shift about on the seat to keep my bum from hurting and I did stand up on the pegs occasionally, but that's just one heck of a lot better than the hour to two hours I had with the stock seat before the modification!!! Enjoy!