85 K100 forks to R90/6

[arbalest]

I am hacking my K100, so have no use for the stock forks. I have an R90/6 with the single disc ATE brake. I have the stock brake working as good as it has ever worked, maybe better. My K100 has (done by previous owner) dual floating discs and dual six pot ISR calipers. I would like to have those on my R90. So, the questions. What spoked wheel can I use to mount the floating discs, and what has to be done to mount the K100 fork legs (I believe they are the same dia.) in the R90 triple tree. I'm assuming the top trees are different enough to require some modification of parts. Finally, can I use the under tank master cylinder with the dual six pot ISR's, or do I have to change the right handlebar controls to use a K-bike master cylinder? If I had to, I would be willing to use the K-bike front wheel. What would be really nice, would be to find a single sided swingarm and final drive from a mono, and then maybe I could use both K-bike wheels. Help me if you can.

Thanks

[Mal S7]

Plenty of pics out there of K front ends on our airheads so it can be done.
I would think you will want to use the K triple clamp though, stronger and you can use a K front wheel.
Not sure what all that will do to your steering geometry though. ??
Have you put a post up on advrider/airheads? More people there that are into modification.

Let us know how you get on.
Cheers
Mal

[arbalest]

Mal,

Thanks for the suggestion. I'll post on ADVRider.

Thanks.

[dougie]

Can you put on the entire front end. (Assuming height is close and the stem works. )
That would be similar to a Monolever bike.
I never had a wobble, or lack of brakes with the Brembos.

[Major Softie]

The only downside is the wheel. If you want to keep spokes, it becomes very difficult. Otherwise, it's really easy: trade out the whole front end.

[Ken in Oklahoma]

Can you put on the entire front end. (Assuming height is close and the stem works. )
That would be similar to a Monolever bike.
I never had a wobble, or lack of brakes with the Brembos.

I'm thinking that a swap of whole K100 forks would be the only viable option for arbalest, and that would be presuming that the head angle between the K100 and /6 are the same--that is unless the fork K100 fork tubes are directly compatible with the /6 sliders. The concern would be the /6 sliders feature the axle leading the centerline of the fork tubes, whereas the K100 sliders are in line with the fork tubes. All other factors being equal the use of K100 fork tubes and sliders would result in a large increase in trail. Said another way if the before and after rake and trail figures aren't close I would expect significant differences in handling (as a minimum)

Or maybe I'm not understanding the problem correctly. Either way I reckon Vanzen or Major Softie will be along to provide a better reasoned statement. (Not that Vanzen and Major Softie are interchangeable )


Ken

[Major Softie]

I assume (always dangerous) that the K trees have a different offset. I only assume this because I know people have traded full front ends over without noticing a big geometry change. I do understand that the K-bike trees have less width, which will result in less travel between steering locks. A Mystic or R100R front end will definitely give you the stock geometry while still gaining the bigger tubes, better fork, and better brakes. I think they will also have the same width as the older R.

[vanzen]

The forks are easily swapped (in their entirity - wheel & all).
Rake, or more aptly trail, is easily adjusted
as the fork tubes can be re-located in the trees.
The difference in offset etc blah & blah is moot
IF
One approaches the project not as a "bolt-on" affair
but rather with a knowledge of mc chassis principles
and specific airhead geometry.

As to spoked wheels ... A more difficult proposition
only solved with a bit of creative engineering and some fabrication.