2001 kx250 front end onto E-series 200

[TheScrambler]

Hello,

I have both an 89 and a 92 KDX200, so for all intents and purposes the same thing. Not sure yet which one will get the front end. I also have in my posession an entire front end from a 2001 KX250 (clamps, stem, forks, wheel, axle with spacers, and brake caliper with hose and master cylinder).

I would like to apply this entire front end to one of my kdx, trying to figure out which route I need to take. I have been searching this subforum for hours trying to find a concrete answer, but came up blank as most people seem to be doing some combo of KX/KDX front end bits, and usually on an H series. So I apologize if this thread is a repeat.

As there is no more RB option anymore, I'll be doing this myself. I work in a machine shop and have access to a press and lathes, so machine work shouldn't be an issue. However, there are two things I'm wondering.

1. Would it be possible to simply get bearings that match the O.D. and width of the KDX head bearings, with the I.D. of the KX stem, and make a spacer to go under the top triple clamp? And if so, is this spacer a common known thickness? Or will I have to measure the height difference and make one for whatever space I come up with?

2. When going the stem swap route, is said vertical spacer no longer required? Just use stock KDX head bearings, and fill the diameter difference in the top clamp with a thin bushing or shim?

If I did go the stem swap route, how likely is it that the KDX E stem is no longer a press fit in the KX lower clamp? Assuming it's still any type of interference fit, I'll probably just use some loctite green for press fit and call it good.

Thank you for any info you may have.

-Jon

[Chuck78]

The stems usually need knurled in a lathe to increase the o.d. .001"-.003" to make it a press fit with retaining compound used

The KX stem height is the biggest issue, it's not the same. Some newer Honda and Yamaha stems are close enough in height to potentially work with the newly available 12mm tall conversion bearing i.d. x o.d. sizes, but not the newer Kawasaki models

[TheScrambler]

The stems usually need knurled in a lathe to increase the o.d. .001"-.003" to make it a press fit with retaining compound used

The KX stem height is the biggest issue, it's not the same. Some newer Honda and Yamaha stems are close enough in height to potentially work with the newly available 12mm tall conversion bearing i.d. x o.d. sizes, but not the newer Kawasaki models

Is there any go-to stem that would be a good length, and also press into the KX lower clamp? Or are you saying that a different clamp and stem assembly entirely would be more ideal?

[Chuck78]

with the KX, stem swap is generally always required unless it's KX500 forks and triples, and those are unobtanium as KX500's are such highly sought after potent machines along with CR500's.

I know of no other stems to swap other than the KDX, except for Showa Suzuki fork swaps. You could try some late 2000's CRF250/450 stems, see f you could get a seller to measure the steering stem from bottom of lower bearing to top of upper bearing seat, same with some 2000's YZ stems. They may be close enough.
Generally everyone considers knurling + retaining compound for a press fit to be 100% acceptable and with zero failures over 2.5 decades or more.

Personally, I would always go an extra 500 miles to run an aluminum steering stem from modern machines to save more weight.

[KDXGarage]

These will be rambling thoughts. Sorry. And this is from 2006, so might not be remembering it all correctly.

I have taken apart a few clamps and did a swap on a friend's 1997 KDX220R with 2001 KX125 forks and clamps. He bought a new aluminum KX500 stem from Emig Racing. It was not the tightest fit, so that was disappointing.

I think the early stems are about 7 thousandths difference. 1.181" KDX and 1.188" KX or later KDX. Something like that.

The stems press down and out /up and in. Shield the bearing, heat the clamp (Bernzomatic propane worked for me). Press down.

I would use the KDX stem and bearings. I think a 3mm washer and a rectangular strip from a Coke can took up the space in my mock ups back then. The Coke can was 0.025" thick to take up the gap inside the upper clamp stem area.

The clamps or forks will hit the tank. Live with it or modify the steering stem stop area on the frame or clamps.

The front end will be 1.something inches higher. Measure the axle to top clamp distance on both. One can only slide the tubes up so far before the front tire will hit the underside of the fender on full bottoming.

MX forks will beat you to death riding slow woods stuff. Revalving is needed. Getting the forks travel limited (shortened internally) is the proper/more expensive way to deal with the height difference. The fork springs will have to be shortened. Shortening a spring makes it stiffer.

KDX stem knurling and compound is what I would look into.

Again, sorry for the rambling thoughts.


I have a 1994 KDX200 that came with an Answer aftermarket upper clamp. It hit the tank and made black marks.

[TheScrambler]

Thank you for the input everyone. Chuck, I found your comment in a thread from ~2 years ago about using the KX stem and the special (all balls 99-3540-5) bearing, with a 1mm thick inverted top hat shaped spacer to take up the space between bearing and stem. I think, having access to a lathe great for making small parts, I will try that. Thanks for that research by the way. I have the 2001 KX frame here, and the head tube length is exactly the same between that frame and the 92 KDX (A shade over 7 3/8). The lower bearing is the same between KX and KDX, and the steering stops interact perfectly. It will need spacing on the frame stop so as not to hit the tank though. The KX stem is slightly shorter in overall length, but the KX top clamp is also a few mm thinner which would make up most of that difference. Let me know if anyone would like some exact measurements while I have the frames and stems side by side. I'll try to remember to let you know how the bearing shim idea works out.

[KDXGarage]

2003+ head tubes and stems are 6 mm taller.

An area to check out is the lower bearing mounting area. Some of the KDX lower clamps are taller, which moved the bearing up on the stem. I remember someone cutting the stem on a lathe to remove a touch of thickness so the bearing would slide all the way down without overdoing it on the press fit. I hope that makes sense.

What is the head tube height in mm? I seem to remember 188 maybe. Just a memory check for this aging man. HA HA

[TheScrambler]

7 3/8 comes out to 187.325mm, so I'd say you're spot on

[KDXGarage]

I'll take it. Ha ha!