86 and newer non-low seats oughtta fit all 86 and newer motobricks except the k1... some require different hardware... 85 and older non-low seats are unique to themselves and are not interchangeable with 86 and newer...
1984 to 1985 seat hinges are different than 1986 to 1997...
1986 to 1992 hinges are different than 1984 to 1985 and 1993 to 1997...
1993 to 1997 hinges are different than 1984 to 1992...
This thread describes the parts for mounting regular and low seats. The regular seat is referred to as a Dual Seat in the BMW parts catalog. The low seat is referred to as a Sliding Dual Seat.
Does my bike have a regular seat or a low seat?
If your bike has side(a.k.a. battery) covers and the seat has hinges on the right side to rotate it open then you have a regular seat. (Sometimes the side covers are missing.)
If your bike does not have side covers and has a rubber surround around the rear of the tank then you have a low seat. (Sometimes the rubber tank surround is missing.)
(Side note: If a regular seat gets you almost to flatfoot then an alternative to converting to a low seat is having the front sides of a regular seat shaved down.)
The L-Jetronic Brain HolderRegular Seat: Under the front of the seat is the bracket (a.k.a. Tool Box) that holds the L-Jetronic fuel injection control unit. It has a compartment with a cover on top of it for holding you toolkit. Parts 1 and 7 in the diagram above.
Low Seat: Since the low seat seat pan dips down into the frame low seat bikes use an L-Jetronic holder (a.k.a. Control Unit Bracket) that does not have a tool box on top of it. Part 9 in the diagram above. If you have a K1100 seat pan where it dips into the frame under the rider then you’ll need one of these since that part of the seat pan would hit the tool box of the regular seat L-Jetronic holder. This part can also be used with a regular seat but having the tool box mentioned above is rather handy.
Regular Seat Mounting HardwareParts 1, 2, 3 and 4 above are the hinges that attach to the right underside of a regular seat. Parts 5-8 are the catch for the seat lock that mount to the left middle underside of the seat. Part 16 is a hinge that mounts to Part 3 and is used to prop the seat up when it is opened. Part 10 is a bow that mounts to the bike under the rear of the seat. It connects to the rear hinge (Part 4) via a hinge pin, Part 14.
When installing Parts 3, 4, 5 and 10 it’s a good idea to leave them a little loose at first, close the seat to get it aligned properly and then open the seat up and tighten them down. The seat catch’s (Part 8) length has a locknut and should be adjusted so that it works properly in the seat lock.
Later K1100s’ seat pans are slightly different than earlier regular seat pans and require different hinges. (They are easy to identify because they have vibration insulating rubber between the hinge and the metal part that mounts to the seat.)
Regular Seat LockThe regular seat lock mounts through the left side of the frame above the left rear corner of the battery.
Information on “rekeying” it to work with your ignition key can be found here:
How to "rekey" K bike locksThe regular seat lock has three key positions: counterclockwise, straight up, and clockwise:
Counterclockwise: When left in this position, the lock is open. Pushing in the lock cylinder releases the seat catch so that the seat can be opened.
Straight up: The seat is locked and cannot be opened. Pushing in the lock cylinder does nothing.
Clockwise: Turn the key counterclockwise and push the lock cylinder in to open the totally worthless helmet lock on the bottom of the seat lock.
Important: Make sure that your seat catch engages EVERY time you close your seat. Sometimes pushing in the lock cylinder in in the open position will help to engage the seat catch. If you don’t then when you sit on the seat all of your weight is sitting on top of the seat catch hook in the seat lock and it will eventually wear through and break, rendering your seat lock useless.
Low Seat Mounting Hardware and LockThe low seat attaches to the bike at three points. There are two hooks (Part 6) that mount to the tail cowl outside the sides of the cover for the tail cowl storage compartment. The front of the seat has a metal “U” (Part 25) mounted to the bottom of it. The front of the seat is held on by the seat catch. (Part 11) When the low seat lock (Part 18) is unlocked and rotated clockwise it pulls on the rod (Part 19) that rotates the seat catch to let go of the U so that the seat can be lifted off. The seat lock catch assembly mounts to the frame via Parts 15 and 16 under the front of the seat
Low Seat Tank SurroundThe rubber low seat tank surround attaches by a middle bracket (Part 3) and two side brackets (Part 2) that stick to the tank. If you’re using used parts and the adhesive is worn out then use something like 3M double-sided car trim mounting tape to mount these parts to the tank.
The "best" (and cheapest) way to convert from a regular seat to a low seat or vice-versa is to find somebody who wants to go the other way and do a swap. You can post here in
The Yard Sale or place a free parts wanted ad over at
The IBMWR Marketplace.
Part numbers:
L-Jetromic Brain HolderRegular Seat Mounting HardwareK1100 Later HingesSeat LockLow Seat Mounting Hardware and LockLow Seat Tank Surround
