‘00 KX250 Swap Items

[Bz1hx]

Hello All,

Yes I know, another ‘will this work’ thread. Bear with me, I’m new to KDX & dirt bike world. 6’ 210 lbs, riding in the rocky mts. Lots different terrain. I have an 01 KDX200 that I think would like to do a fork conversion on. Even being newish to dirt, I’m starting to feel the limitation with the front fork. I have a line on a complete ‘00 KX250 rolling shell for basically free. From what I understand that the forks should be an easy swap after swapping the stem? (plz correct if wrong). Would it be worth pulling other parts from the KX250 as well? Any input would be greatly appreciated!

[SS109]

If your going to do it get the whole front end. Forks, wheel, and axle. Yes, you need to swap the KDX stem into the KX250 lower triple clamp. Sometimes the fit is perfect and sometimes you need to knurl the KDX stem to fit the lower triple clamp properly. You also need to come up with something for a spacer to fill the gap between the upper clamp and the top of the bearing retaining nut and something to fill the gap caused by the smaller KDX stem going into the larger opening of KC upper clamp. People have come up with lots of different ways of accomplishing that so read up here on the forum about what others have done. If you have a lathe you can make a one piece bushing for it. If not, I do make them and charge $55 plus shipping or I can do all the work for $125 plus shipping.

[Bz1hx]

Thanks for the response! If I go for it, I’ll get the whole bike. It’s a frame with suspension wheels and tires, engine and drivetrain are missing. Is this something that is worth doing? I’ve heard it is, but I’d hate to make irreversible changes to a perfectly good KDX. I do intend on keeping the KDX indefinitely, so I’m not adverse to upgrades. Just want to make worth while upgrades.

[SS109]

Yes, a front end conversion is absolutely worth it IMO. Of course, this comes from the perspective that my KDX was built for racing, to handle whoops, and some fairly high speed singletrack. If you were riding nothing but hike-a-bike TKO terrain I would say stick with the stock forks. Also, doing a fork swap is NOT a permanent change. You can always swap back to stock forks at any time providing you swap stems again or pick another complete KDX lower triple clamp.

BTW, if you're getting a complete roller KX250, you could just build a KDX/KX hybrid. Just an idea!

[Bz1hx]

We have everything over here from steep rocky enduro trails, sandy high speed whoops, to woods and dirt. I had the KDX up at 10,000 feet on Saturday up a trail with nothing but loose shale. It struggled, but made it! I realize that there’s nothing I can do to make it good at everything, but this seems like a reasonable upgrade. The KX is just a frame and suspension. Everything is missing aside from the frame, suspension, wheels and tires. It would be quite a project to do a hybrid I think!

[SS109]

Ah, I see. Yeah, doing the front end swap would be a lot cheaper to make happen then. Shame, the KX250 chassis would be lighter weight and handle whoops/high speed stuff better.

[Bz1hx]

Is it worth pulling anything else off the KX other than to re-sell?

[SS109]

Yeah, pretty much everything can be sold off that's left. Check Ebay for pricing and sell them cheaper to unload them.

[Bz1hx]

Is there a massive benefit to having the forks revalved? I’ll have the seals done before they go on the KDX but wondering if there’s anything else that should be done while they’re off the bike?

[KDXGarage]

MX forks will generally be rough in slow, technical terrain.

[SS109]

Yep, definitely get them revalved for off road riding unless you're an A/Pro racer.

[Bz1hx]

Hello all. Reviving this thread. I have all the necessary parts for the swap aside from the triple clamp spacer and have done a lot of reading on the ‘01 KX250 forks. It’s clear that the forks will need to be rebuilt (they’re leaking), which seems easy enough. At this point, I haven’t taken them apart. I think I have a good understanding of removing shims on the base valve, removing the bladders (idk if they’re there, will report back), and the mod on the restrictive barrier.

I’ve realized that I will need help with the mid valve though. Seems some people leave it alone, some people replace the o-ring with a spring (where to get said spring, idk), and some people play with the shim stack.

I know this will take some trial and error once the swap is complete. In the meantime, any guidance would be greatly welcomed. I’ve never touched a fork but I’m confident in my ability to turn wrenches and follow directions!

[KDXGarage]

Be sure to read up on filing the peening off the top of the base valve.

Race Tech used to sell the springs that go in the midvalve.

I did a set of 2001 KX125 forks many years ago. After research and suggestion from a UK tuner, I went with 0.4 mm of float.

Be sure to replace the inner and outer bushings on the tubes, not just the oil and dust seals.

[Bz1hx]

Be sure to read up on filing the peening off the top of the base valve.

Yep, most of what I’ve read boils down to be careful and don’t go nuts with the file.

Race Tech used to sell the springs that go in the midvalve.

Unless that’s now apart of the gold valve kit, I don’t see a separate part for this. Entirely possible that I’m wrong though. The current gold valve kit appears to be compression only.

I did a set of 2001 KX125 forks many years ago. After research and suggestion from a UK tuner, I went with 0.4 mm of float.

This is where I’m getting stuck on how to set the float.

Be sure to replace the inner and outer bushings on the tubes, not just the oil and dust seals.

Parts on order

[KDXGarage]

They sold just the springs for the midvalves. Their old printed instructions recommended pulling the o-ring and using a spring.

Adjust oil quantity if you pull the bladder parts instead of just disable them.

[Bz1hx]

They sold just the springs for the midvalves. Their old printed instructions recommended pulling the o-ring and using a spring.

Adjust oil quantity if you pull the bladder parts instead of just disable them.

Ya I don’t see them on racetech’s website. I might call them and see if they have some old stock. Do you happen to have the part number? Found a good write up for setting mid-valve float. The KX forks as they sit feel more plush than I would expect for an MX fork. Maybe I’ll get lucky when I take them apart

[KDXGarage]

Sorry, but I don't think I have the part numbers. I used them in 2006.

[Bz1hx]

I ordered a second KDX steering stem off eBay for the swap so I have two complete front ends. It’s in serviceable condition, but not great. The KX steering stem is in excellent shape, and that got my thinking. The bottom bearings between the KX and the KDX are identical, 30x55x17. The top bearings as as follows.. KDX: 25x47x15. KX: 28x52x16. So, hypothetically, a 28x47x15 bearing should bridge the gap. I read some old posts. In the past, it seems that such a bearing didn’t exist. But it does now! $40 on Amazon. This seems too easy though. Is there something I’m missing? Obviously, I haven’t tried it. But for $40 it seems worth the gamble to try it.

[bufftester]

The other key part of that is the stem length. You may need a space under the top nut to make up the difference.

[Bz1hx]

The other key part of that is the stem length. You may need a space under the top nut to make up the difference.

Yep, aware of that, just forgot to include it in the previous post. I would imagine that should be an easy hardware store item as a temporary solution.