Fork options

[Octo777]

I presently have 2003kx250 forks on my kdx220 with the kx250 triple tree. I have damaged one of my forks. Before I decide to buy another kx250 fork is the a better or more modern fork that will fit the 2003 kx250 triple tree? Any input would be appreciated

[KDXGarage]

You should try to get another fork leg like you already have, if possible. If you want newer forks, then 2004 and newer will have the newer brake hose routing style. 2003 - 2008 KX250 two-stroke forks will fit those clamps. 2003 - 2008 KX125 will fit those clamps. 2004 and 2005 KX250F forks will fit also. I think 2006 and newer 250F and KX450F may have a slightly different diameter in one of the fork clamp areas. Otherwise, the aluminum framed KX250F and KX450F have different steering stop styles that mean you need to modify them to fit a KDX frame. Look at some of the clamps, and it should be apparent on the steering stops.

[Octo777]

I damaged the internal fork cylinder. Do you know is the internal fork cylinder for the 2003 kx250 fork the same as 2003 kx125 fork. I looked at part online they have slightly different part numbers.

[KDXGarage]

I don't know for certain, but I assume it is due to different valving. The diagram number is F2340 on both diagrams.

[Chuck78]

Those internals should be swappable, but will have different valving between the KX125 & KX250, so you would either need to swap or change all of the mid valve/rebound valving to be matched, or swap the internals as a complete pair.

[Octo777]

My springs in the 2003 kx250 forks have been shortened Will they work in 2004-2008 kx250 fork or are they specific to the 03. Also is the 2003 wheel and axle bolt interchangeable.

[Chuck78]

You can find out by looking up both models in the RaceTech.com product search, fill out the pop-up box info with your weight, riding terrain, riding style/level, etc, & it will bring up the fork spring part #'s for each. Compare to see if they're the same, or look up their product listing for fork springs via the menu > downloads link > scroll down to the fork springs file, and compare diameters of both springs if the part #'s are different.

[KDXGarage]

2003 KX250 springs won't work in 2005 - 2008 KX250. The 2004 forks were the last year for single chamber. 2005 and newer are dual chamber.

[Mcoleman986]

Does anyone have the machining specs for the 2001 KX/KDX stem swap? I've heard the gentleman from RB designs retired?

[Chuck78]

No real specs are needed, just have a machinist dig into it with the hard parts in hand, as it's all self explanatory with a brief description of what needs done. It varies with every different combination as well. Some tears KDX stems somehow are a press fit into the KX erc triples, other years are .001" to .003" too small and need knurling on the press fit surface to increase the diameter slightly, and then be peessed back in using retaining compound to hold it.
Then a tophat reducer bushing needs machined from aluminum to mate the KDX stem to the larger o.d. triple clamp.

Nowadays you can get the KDX frame bearing o.dm in a 12mm tall 28mm i.d. and 30mm i.d. specialty bearing for swaps, so if your swap candidate's steering stem is tall enough, you no longer have to swap the heavy outdated steel KDX steering stem into all donor triples. Some 2000's/2010's Yamaha and Honda aluminum steering stems are the ones up for consideration for retaining the much nicer aluminum steering stem. You'll need a 3mm spacer the o.d. of the steering stem to sit on top of the bearing. AllBalls sells these. ChopperPilot was writing about this on here recently, but being in Alaska, he doesn't have time now to test it all out although he has the parts. His riding season is nearing an end, and he'll get to it when his days get significantly shorter heading towards cold weather and 24 hours of darkness in winter...

[Mcoleman986]

thanks for the info!

[SS109]

Does anyone have the machining specs for the 2001 KX/KDX stem swap? I've heard the gentleman from RB designs retired?

Are you talking about the top triple clamp bushing he made or the knurling he did?

I just made a bushing and had to knurl the stem for a member here. I can make more but my price is $55 plus shipping or I'll do the bushing, knurling if needed, and press them for $125 plus shipping.

[Mcoleman986]

I have the triples for the '01 220 and the '01 KX 125, I would like to be able to use my stock wheels with the speedo cable and I read that RB designs did and axle mod with a spacer to be able to use the stock axle of which I have 2. Send me your info and I will definitely consider having you do the mods for me

[Chopperpilot]

I have the triples for the '01 220 and the '01 KX 125, I would like to be able to use my stock wheels with the speedo cable and I read that RB designs did and axle mod with a spacer to be able to use the stock axle of which I have 2. Send me your info and I will definitely consider having you do the mods for me

My $.02...... I think with the significant inventory (on ebay) of front wheels to match whatever fork setup your running, and the relatively easy and cheap mounting of a trail tech computer (the cheaper one), why people don't just go with the MX wheel and axle setup? The MX axles (even the early/mid 90's ones) are a stiffer and less flexy setup than the KDX axle and wheel. Larger wheel bearings, larger diameter axle, and larger clamping surfaces all add to less deflection and better strength. The added bonus being that the MX setups are all lighter as well (especially when you add in the axle adapters). That being said, I may keep the KLX fork/axle/wheel setup on my KLX 650R (it's the same axle/wheel as the KDX) for a couple of reasons:
1) I have gold valves in the KLX forks and they are awesome
2) now that I swapped a KX front end onto my KDX, I have an extra wheel that'll mount right up. So I have one setup with a regular dirtbike knobby and one with a TKC80 tire for the road.
3) I'm not going to be doing as technical stuff on the KLX650 (probably, although as I've gotten better at riding this summer I've noticed doing the same things on the big bike aren't that hard)

[Mcoleman986]

Thanks again for the feedback!

[SS109]

I have the triples for the '01 220 and the '01 KX 125, I would like to be able to use my stock wheels with the speedo cable and I read that RB designs did and axle mod with a spacer to be able to use the stock axle of which I have 2. Send me your info and I will definitely consider having you do the mods for me

I admit I have no clue on what he did for the axle conversion as I've never seen one in person and I've always used the wheel that went with the donor forks. That said, I agree with all the points Chopperpilot made.

[Chuck78]

Definitely just run the larger diameter axle & larger bearings KX etc wheel that matches the fork swap. More durable and less flex, and no mechanical speedometer drive to hassle with.