So to lower USD forks:
Take 1 set of Showa 46mm USD forks
With a 14mm allen key and an impact wrench loosen the bottom retainer nut (it does not come out)
Once that is out using an 18mm socket remove the top cap, having the forks in the triples helps here.
Once removed pull upward and youll end up with this:
Now with a 18mm wrench and 18mm socket remove the top spring retainer:
Once thats removed you have this
Grab the vice grips and clamp them onto the shaft real tight, and with a 14mm wrench and a hammer give the valve body a good whack to break it loose, then unscrew it.
Remove the top out spring and then slide your spacer one, mine is 2.5" schedule 40 1/2" OD PVC. Metal would probably be better.
Screw the valve body back on.
Here you can cut your spring if needed, mine came from a light dirtbike, so i decided to not cut the spring and see how the extra preload does. Chances are ill have to take it back down and cut an inch or so off the spring, but hopefully not.
Reassemble and admire one shortened fork:
Disregard all the oil on the camera lens, its an oily process
Retighten bottom allen bolt
Rinse and repeat.
First one took about 45 minutes as i had to figure out how to do it, second one took literally 3 minutes start to finish.
So now the WR250X supermoto forks are 33.5" long as opposed to 36.
Stock travel is 11" so I am now down to 9.5" which for my purposes should be more than enough.