It's not going to be a straight swap by any means.
- think about the triple tree compatibility, stem length, stem bearing diameters, offset, etc.
- think about handling as you affect trail, steering angles, etc. on the front wheel
- think about how you will adapt late-model Japanese controls to mid-eighties German electrics
- think about how you will adapt a Japanese throttle assembly to the K-bike throttle body assembly
- think about how you might need to adjust the K-bike's suspension components to return a level stance to the motorcycle when you add shorter forks
- front brakes might be straight forward
I researched this topic some time back and squirreled away information for later use (which never materialized). Here is some of that information I gathered about the K75 Headset Dimensions. K100LT should be the same.
Pivot Stem:
Length from top of lower triple clamp to top of threads: 176mm
Length from top of lower triple clamp to where tapering begins: 128mm
Diameter (to fit inside bearings): 28mm
Note that I ignored the portion of the steering stem that goes into the lower triple clamp
The K1200 axle is 20mm dia. and the k1100 axle is 25mm dia.
Frame:
Steering head length: 165mm
Steering bearing seat diameter: 52mm (BTW, this matches the outside diameter of the bearings I bought for the 1992)
Standard headset bearings (upper/lower) are 28 I.D. X 52 O.D. X 16 thick
Although not K-bike specific, here is some Useful information from Triumph forum on Triumph Sprint conversion to USD fork
http://www.triumphrat.net/hinckley-classic-triples/164910-zx7r-96-03-usd-fork-conversion-legend.htmlI've a set of forks & yokes on the way. They have a matching 25mm axle & take a variety of 4 pot or 6 pot (90mm, T3, Suzy TL/'Busa) mount axial calipers, aligned for a 320mm disc(s). So I plan to keep my Legend spoked front wheel.
*The ZX7R has some of the longest USD forks fitted to a sport bike at 30", much longer than Suzuki options. I expect a net lowering around 20mm. That will steepen rake, but less offset on the Kawa yokes will likely net out with a little more 'trail' - keeping things on the stable side.*
* edit: It turns out the ZX7R forks are 28.5" (
The ZX9R (early, B model) forks are ~ 30"
However, the shorter length works fine when using the Kawa stem & top yoke.http://www.triumphrat.net/t3-sport-touring-forum/164297-tokico-six-pot-measurement-needed-3.htmlFork length to axle c/l is 30". Offset is 30 to 35mm. Stem length 235mm. Axle is 25mm & the ZX7 used a mechanical speedo drive, so should have room for mine.
The tricky bit is the top which needs an OD of 52mm for the T3 frame. 30mm ID bearings are available, but not 35mm it seems. I've found just one supplier of a 34/52 taper roller - Pyramid, who seem to market fork seals & other stuff. There quality is a bit of an unknown? Presumably the 34/52 size fits some stock bikes & there would be an oem option, but I've no idea what machines.
The other option for the top is a double row angular contact ball race, 52mm OD, 40mm ID. It has the same load rating as the stock single row ball race on T3s. I figure a sleeve would be an easy fab - I have a mate with a lathe & he says no problem. Usefully this bearing is only 12mm deep, so might be handy if the stem length is tight - it's hard to be 100% about this not knowing exactly the respective depths of Kawa & Triumph top yokes, stem nuts etc. google_ad_section_endSome ZX7R stem dimensions. The lower bearing mount diameter is 35.00mm, the upper 34.95mm. The top of the Legend headstock tube will be level with the top of the adjustment thread section, point 'A'. The lower seal will locate on the 6.4mm x 43mm diameter section.
The height of the headstock tube is 183mm, with bearing recesses top-18.8mm & bottom 17mm.
