well ill be buggered lets see if i can find some of them does that mean my head stem is cr too??
after the pics agreed with sandblaster...
this are very good forks, but i think the 125-springrates are much to soft for your 250..also the double piston nissin-brake caliper is way better than the oem-one piston tokico that was used from 82-88 ..thats the reason why i fitted one to my 83 kx250 that also use 88-forks

your headstem is definetely kx125-500 85-88 . i have a complete 87-fork in my spares.
conventional kx -forks from 83- 88 use the 43mm fork legs (same diameter as yours) so is for same diameter forks of other makes no diferent triple tree steering stem needed.
and after i showed my bike with the 89- usd-forks , you still ask of the fitment of the later usd-forks?

the stem-bearings kx125 /250 /500 are same size from 1980- 1991 (except: kx500 never changed untill the last year 2004)
kx125/250 became a new stearingstem with bigger bearings in 92. now you have a big range of years and forks, where you can choose from.

little kx-fork history
89/90 41mm usd fork (except us-models with conventional kayaba 46mm in 89)
91-95 43mm fork (kx500 91-96)
96-2001 46mm fork and also change to the newer nissin brake caliper (kx500 46mm fork 97-2004)
2002-2008 48mm forks in kx 125/250, kxf 250/450
and at least: here is what i realize at the moment a conventinal wp extreme 50mm fork (from a 99 husaberg fe501) to my 87 . in the next days i have to figure out, how to fit the brake. i think it ends up with making another handmade adapter like on my 83 kx250..
http://img.webme.com/pic/d/der-motopunk/foto0173.jpg more to see on my website:
www.der-motopunk.de.tl or here in my build thread :
http://www.kxriders.com/forums/index.php/topic,11655.msg95606.html#msg95606