"De-mush" K100 Handlebars

"De-mush" Handlebars

(Does not apply to K75s.)

K100s, K1s and K1100s all have rubber bushings where the handlebars mount to the upper fork tree. The purpose of this is to minimize the amount of engine vibration transferred to the rider's hands. However, a side effect of this is that it can make the steering on these bikes somewhat mushy.

(Because the K75 engine runs so smoothly the handlebars on those bikes are solidly mounted to the upper fork tree without any bushings.)

If you find the steering on your four cylinder K to be too mushy for your liking then you can simply add some washers to firm up the steering.

The first section of this covers how to do this to a 2 valve K100. The section following that describes how to do it to a 4 valve K bike. (K100RS4V, K1 or K1100)

"De-mush" K100 Handlebars

The clamps for K100 handlebars are mounted in large rubber bushings in the upper fork tree. This means they can move around some and be mushy. A simple solution is to harden up these mounts by adding 1/8" think bronze thrust washers under the top and bottom washers of the handlebars mounts. (I used thrust washers with a 1" outside diameter and a 5/8" inner diameter.)

K100RS4V, K1 or K1100 Handlebars

The handlebars of a 4 valve K bike can be "de-mushed" by simply adding a thrust washer under the #4 rubber bushing on each side. See the red circle in the parts diagram above.

Since you're just adding a washer underneath each bushing this is a pretty simple and quick modification that can be done one side at a time without any major disassembly.

The #6 nut is usually covered with a plastic cap that needs to be pried off.
Then unscrew and remove the #6 nut and the #5 washer above it.
Install a thrust washer above the #5 washer and reassemble.

The best washer to use for this is a 1/8" thick thrust washer with a 1" outside diameter and a 5/8" inner diameter.

Although it sounds simple enough, the tricky part is getting the thrust washer centered so that it rests inside of the hole in the fork tree and also so that the bottom of the #2 handlebar clamp can pass through it. It needs to be well-centered with respect to both of those parts in order to apply good compression to the #4 rubber bushing.