RM/DRZ front end to KX250

O.K., I love conventional forks. I have put 87 CR forks on my ATK, Marzocchi 45 magnum on my 93KX250, and WP50mm Extremes on my KTM520. I am curious as to whether anyone has adopted the 96-98 RM or DRZ400 forks/front end onto a KX 250? I just thought I would ask before looking to see how much machine work will be required. I already have the forks, brake, and front wheel from an RM but am waiting on the triple clamps to see what needs to be done as far as bearings/stem, etc. Appreciate any help. :thumbsup:

I don't think it would be too much trouble. Here's my KDX220 with DRZ Showa forks.


Oooooh, I'm ALL excited now! Very sweet! Question: Did it bolt up w/o modification or did you have to make a spacer for the clamps, change stem and or bearings? Also, how did this change the handling for you. I'm going to start off with the stock valving and the spring rates in the DRZ forks (.44) are good for my 190 lbs. I also have an Ohlins shock ($200 on Ebay) that I'm sending off to have revalved for my type of riding/racing. Thanks for posting the pic, your bike looks great. Take care and have a great week!

I used the stock trees but had to have a custom stem made and used the KDX bearings. I was gonna use the KDX stem but the O.D. was too small where it pressed in the lower tree. Also had a spacer made for the top clamp, OD and ID diferences and had a custom axle made. BUT it was a major improvement in handleing as the 49mm Showas are great forks for off road. No comparision to the wimpy things that came stock on the KDX. Any questions I'll try and help.

I'll have to wait and see how the KX differs from the KDX as far as stem measurements, if it does at all. Did you have a local machine shop do the new stem? If so, possibly they recorded the measurements in case the KDX and KX stems are the same and then I could contact them to have them make me up one that replicates yours. When I lived in Kansas, I knew a great guy in Topeka with a machine shop in his garage that did outstanding work. Down here in the Hill Country of Texas, I would have to start asking around and looking in the phone book (which I might do anyway just to get a jump start). I can imagine that the 49mm's worked a bunch better than the stock 43's. I used to work in the industry and I know that the stock KDX forks were pretty limited. It made a MASSIVE difference putting the 50mm Extremes on my KTM 520 as I have never really liked the inverted WP forks (had them stock on my ATK's, Husaberg, and KTM's).

Once again I thank you for your help and input on this project. Don't you just love the internet? LOL. Take care.

Actually my best friend has been a tool maker for the last 28 years. He made it at work in between his "regular work". I know the KDX and KX stems are differnt but by how much I don't know.

Here's some info that I copied from another site that might help.

Post subject: Dimensions for yourreference: 2000 KDX and 2001 KX125 triple

I got the calipers out and made a few measurements last night:

KX upper triple hole ID= 25.03mm

KX upper triple thickness=20.27mm

KX stem OD at upper triple=24.95mm

KDX upper triple hole ID=23.54mm

KDX upper triple thickness=24.5mm

KDX stem OD at upper triple=23.42mm

KDX stem at lower triple= 30.15mm

KX stem at lower triple= 30.15mm

KDX lower triple hole= 30.13mm

KX lower triple hole= 30.13mm

Took 10 tons to press out the KDX stem!

Here's a updated pic


Thank you again for the info. I guess I will take the two sets of triple clamps and stems to a machine shop and let them carve one up for me. I've pressed out a few stems in my time and I know how tight the press fit is. Even heating with a propane torch didn't help it out much. I really appreciate you providing direction with this. Have a great week.

Just FYI the RM forks are twin chamber units, to the best of my knowledge the DR-Z forks are not (although they are a quality cartridge design, they are not as sophisticated as the RM forks).

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