Does a low (29") seat from an '86 K75/100 fit my '85 K100 that is now equipped with a high (31") seat ? The seller on eBay isn't sure and I don't need a seat that won't fit.

Thanks !!

Klausmeister,
The K100 normal seat has a hinged type fitting with your toolbox under..
The Low seat fits with 2 slots at the rear and a loop at the front with no toolbox.
It is easy to go from Low to High by adding foam..but not from High to Low.."So forget it".

If you do decide to try it you will need the tank/Knee surrounds to go with it.
Your best bet is to reduce the foam from the High seat.
I'll post some pictures.
Ajays.

What Ajays forgot to mention is that the 1985 K100 and 1986 K75 don't have the same cowl. The original 1985 seat had the handles built on and the 1986 the handles are on the cowl. The back shape of the cowl is different.

A K75 low seat can be installed on a 1985 K100, but you will have to replace the cowl as well as "shave" the height of the tool box. The K100 and K75 gas tank is slightly different and I don't think the knee pads would fit the K100 tank.
BMW never offered the low seat option on the 1985.

Thanks, Ajays and Crazy Frog
Based on your information, I'll try to modify my existing seat. If successful and half-decent looking, I'll post the result.

What the professionals are using to trim the foam is an electric knife.
Just sneak into the kitchen, and borrow your wife's one

Hint only do that whilst SWMBO is out and put it back before she gets back!
Regards,
K-BIKE