*** FORK LOWERING ***
I've yet to see another KZ750 twin dropped internally like this, and I really wanted to lower my stance to equal to or shorter than those seen in previous pages of this thread, but without the fork tubes protruding past the top triple clamp like done by so many builders (including my inspiration, Wrenchmonkees).
Starting point. I didn't document the removal of the forks from the frame, becasue if you can't do that, you shouldn't bother attempt the simple procedure below. I stole this method from the folks over at the XS650 forum.
my source of info: http://www.xs650chopper.com/2009/06/mulligan-machine-lower-your-xs650-forks-low-buck-garage-tech/
First, drain as much of the oil as possible via the tiny drain screw at the bottom. Pump the tube to squirt it out. Warning: this can make a mess if you're not careful, and it smells awful.
Next, unscrew the top cap via a 1/2 drive ratchet, and remove the main spring. Mine is the non-progressive one on top. The other is from a 4 cylinder KZ750 that I thought I might be able to use, but unfortunately, the OD of those coils is about .5mm too large to fit inside my fork tubes, despite the OD of both bikes' fork tubes being 36mm.
Now came the tough part. I had trouble removing the damper rod bolt from the axle side, as the damper just spun, and I didn't have the 'special tool' Kawasaki recommends to hold it still from inside the fork tube. So, per the instructions from the guys over on the KZ twin board, I cut down what is essentially a broomstick and jammed it in there, while I hit the lower bolt with an air impact to shock it loose.
This is obviously after the damper rod had been removed from the fork leg.
The contents all laid out in their approximate orientation of assembly. Not shown is the fork seal, which is still in the casting.
These are the spacers I cut down from some scrap steel tubing. I've heard of folks using PVC for this, but I feel better about having metal in there. I don't know why I didn't buy a pipe cutter years ago. This thing is awesome. Clean, straight cuts every time. These spacers will be de-rusted before final assembly. This was all just a dry mock-up until I can find some 15W fork oil.
Placement of those spacers:
Re-assemble everythig in reverse order, again using the broom stick to allow proper tightening of the lower damper bolt.
Now you're left with a main spring that is a little too long. Some of this needs to be cut. As suggested my the XS650 chopper link above, I cut slightly less away from the main spring, as the spacer was long. Spacer = 1.75". Spring reduction = 1.5". This creates a slight increase in spring preload. As a heavier rider, on what I considered to be a very soft set of forks, I thought this would help. I may add a tiny collar up top to add even more preload but that can wait.
I cut that top section of the main spring with an angle grinder, then ground it as smooth / flat as possible. The increased preload was not a major change, and I was still able to re-install the top cap with one hand. Note that I haven't added oil (don't forget that step), but I wanted to show the before & after lengths as seen below.
I still need to perform this on the second fork leg, so full bike photos will have to wait for another day. These cut springs with added preload feel a tad stiffer than stock, but it's hard to compare without any fork oil. I'll give my report on that issue when I have some in there.
I hope this helps some foks in the future.