YZ250F forks onto KDX

Questions and comments about converting to beefier forks..
Hendrikder
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YZ250F forks onto KDX

Post by Hendrikder »

Good Day everyone

Just a quick question , will I be able to fit a 2009 YZ250F forks (it is FX forks) or the entire front end onto a KDX 200 2006?

Just want to know because I have access to a set of forks or the entire front end or steering set.

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oldmxer95
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Re: YZ250F forks onto KDX

Post by oldmxer95 »

You will need to swap the steering stem, but have it knurled to fit the YZ lower clamp. You will also need the YZ front wheel and brake caliper bracket, and then also modify the steering stop. Just did this swap with a set of YZ426F front end.
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Hendrikder
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Re: YZ250F forks onto KDX

Post by Hendrikder »

oldmxer95 wrote: 09:04 am May 09 2019 You will need to swap the steering stem, but have it knurled to fit the YZ lower clamp. You will also need the YZ front wheel and brake caliper bracket, and then also modify the steering stop. Just did this swap with a set of YZ426F front end.
Thank you very much

You can't maybe give me a more detailed description pf how you did it? I to have access to a entire YZ frame everything on it except for the engine so I can use what ever I need to swop the front end.

And how is the feeling on it after you changed it go the YZ setup?

Kind Regards
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Re: YZ250F forks onto KDX

Post by oldmxer95 »

1st - Have a machinst press out your stock stem from your bottom clamp. Provide him the lower Yamaha clamp, and instruct him to knurl the stock stem to press in snug into the Yamaha lower clamp.

2nd - Fashion a steering stop that works. I have not done this yet.

3rd - Since the Yamaha forks are longer that the KDX forks, you will need to shorten them internally about an inch or slide them up in the clamps as far as allowable.

4th - When installing the top clamp, you will need about .025 feeler gauge to wrap around the stem to make sure it has a slightly snug fit.

5th - Install forks, install the YZ front wheel and brake caliper.

These should be the major steps and get you on your way.

As far as feeling, this coming weekend is the first chance I will have to ride it.
95 KDX 200H, 98 KX250-K5, 84 KX125-C1(Project), 21 Husqvarna FX350
If it doesn't burn dead dinosaurs, then it must be someone else's hobby. :kick:
Hendrikder
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Re: YZ250F forks onto KDX

Post by Hendrikder »

oldmxer95 wrote: 02:21 pm May 09 2019 1st - Have a machinst press out your stock stem from your bottom clamp. Provide him the lower Yamaha clamp, and instruct him to knurl the stock stem to press in snug into the Yamaha lower clamp.

2nd - Fashion a steering stop that works. I have not done this yet.

3rd - Since the Yamaha forks are longer that the KDX forks, you will need to shorten them internally about an inch or slide them up in the clamps as far as allowable.

4th - When installing the top clamp, you will need about .025 feeler gauge to wrap around the stem to make sure it has a slightly snug fit.

5th - Install forks, install the YZ front wheel and brake caliper.

These should be the major steps and get you on your way.

As far as feeling, this coming weekend is the first chance I will have to ride it.
Thank You very much for the reply.

I will definitely be looking into doing the swap then as it does seem very complicated or to difficult.

Please let me know about how your ride goes with the new forks.

Kind Regards
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Re: YZ250F forks onto KDX

Post by oldmxer95 »

Just got back from an event here in the northwest called Class X. If focuses on 2 strokes from every era. Rode my KDX with the YZ426F forks in the Revolution 2, 60+ Intermediate and they worked fantastic. Now I may have a little work to do on the rear end but the front was way better than the stock forks. I still need to figure out a permanent solution for the steering stops. Anyone got ideas?
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Re: YZ250F forks onto KDX

Post by doakley »

What’s the problem, new forks hitting the tank? Try drilling and tapping an aluminum bolt into the Yamaha steering stops to let them hit the bolt heads. Not sure if this approach works for Yamaha but it worked when I put KX forks on my KDX.
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Re: YZ250F forks onto KDX

Post by oldmxer95 »

Thanks, I'll take a look to see if that will work.
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Re: YZ250F forks onto KDX

Post by doakley »

So here’s a question. If you have the entire YZ rolling chassis, which is a known good handling bike, why not just move the KDX engine into the YZ frame? Must be possible.
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Re: YZ250F forks onto KDX

Post by oldmxer95 »

I only had the front fork assembly not the whole rolling chassis.
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Re: YZ250F forks onto KDX

Post by doakley »

oldmxer95 wrote: 10:35 am May 14 2019 I only had the front fork assembly not the whole rolling chassis.
Sorry, that post was directed to Hendrikder who said he had everything but the YZ motor.
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Re: YZ250F forks onto KDX

Post by Hendrikder »

doakley wrote: 01:47 pm May 14 2019
oldmxer95 wrote: 10:35 am May 14 2019 I only had the front fork assembly not the whole rolling chassis.
Sorry, that post was directed to Hendrikder who said he had everything but the YZ motor.
You see the thing is it is a friend of mine who wants to sell the bike as parts, so I can get a decent prize on the front end. Would be out of my price range to buy the entire frame.

I will be taking on this project in the coming months, putting the YZ front end into the KDX.

Will keep you updated, so the only problem I see is with the steering stop at the moment?

Kind Regards
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Re: YZ250F forks onto KDX

Post by Kawasakirooster »

Any body here know if 1999 wr 400 triple clamps would be a good choice for this set up
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Re: YZ250F forks onto KDX

Post by oldmxer95 »

They will work as long as you use a knurled KDX stem. Then yes the only problem left is addressing the steering stops. I too have not done this yet, I am still looking for a good workable solution.
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Re: YZ250F forks onto KDX

Post by TurboJAM »

Hopefully reviving this old thread..... any updates on this?

How did the swap go?
Did you need the brake calliper bracket, or the complete front calliper with bracket?
Any photos?

I don't have the front Yamaha axle yet to compare to my stock KDX but thinking of getting a custom made axle so i can use the KDX wheel.

I've got a set of 2009 yz250f forks, 2008 triple clamps (so only have one position for bar clamps, not two like 2009+).

Currently sourcing all the parts before I start the build.

Cheers
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Re: YZ250F forks onto KDX

Post by KDXGarage »

Any forks with 48 mm inner tubes are going to have even larger outer tubes and triple clamps. Turn the handlebars all the way to the left or right and it is going to whack the top of the fuel tank. One can live with it or use a method to keep the bike from fully turning left and right.

Anyone who is considering USD forks needs to go measure (envision) the larger clamps with the stock clamps turned fully left or right.
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Re: YZ250F forks onto KDX

Post by jaunt »

oldmxer95 wrote: 09:07 pm May 11 2019 Just got back from an event here in the northwest called Class X. If focuses on 2 strokes from every era. Rode my KDX with the YZ426F forks in the Revolution 2, 60+ Intermediate and they worked fantastic. Now I may have a little work to do on the rear end but the front was way better than the stock forks. I still need to figure out a permanent solution for the steering stops. Anyone got ideas?
Did you get them revalved?
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Re: YZ250F forks onto KDX

Post by Chuck78 »

jaunt wrote: 12:34 pm Oct 09 2023
oldmxer95 wrote: 09:07 pm May 11 2019 Just got back from an event here in the northwest called Class X. If focuses on 2 strokes from every era. Rode my KDX with the YZ426F forks in the Revolution 2, 60+ Intermediate and they worked fantastic. Now I may have a little work to do on the rear end but the front was way better than the stock forks. I still need to figure out a permanent solution for the steering stops. Anyone got ideas?
Did you get them revalved?

There's a local KDX200 guy here who swapped I believe 2008 or 2010 YZ250FX forks onto his H-Series KDX. He was ecstatic about them, but I believe did say they could use a little bit of revalving still for a little better plushness.
If I'm recalling correctly, he just mentioned doing some lathe work on the steering stem and triple, and then they bolted right up???

FYI the post you were replying to about revalving was 4-1/2 years old...
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Re: YZ250F forks onto KDX

Post by jaunt »

Chuck78 wrote: 05:24 pm Oct 10 2023
jaunt wrote: 12:34 pm Oct 09 2023
oldmxer95 wrote: 09:07 pm May 11 2019 Just got back from an event here in the northwest called Class X. If focuses on 2 strokes from every era. Rode my KDX with the YZ426F forks in the Revolution 2, 60+ Intermediate and they worked fantastic. Now I may have a little work to do on the rear end but the front was way better than the stock forks. I still need to figure out a permanent solution for the steering stops. Anyone got ideas?
Did you get them revalved?

There's a local KDX200 guy here who swapped I believe 2008 or 2010 YZ250FX forks onto his H-Series KDX. He was ecstatic about them, but I believe did say they could use a little bit of revalving still for a little better plushness.
If I'm recalling correctly, he just mentioned doing some lathe work on the steering stem and triple, and then they bolted right up???

FYI the post you were replying to about revalving was 4-1/2 years old...
I realize that, just looking for any info. I've got a pair of YZ forks to swap I just didn't know if a revalve was totally necessary.
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Re: YZ250F forks onto KDX

Post by KDXGarage »

MX forks are valved for MX, not woods. They almost always benefit from a revalve. I have a 2005 KX250. It beat me to death in the woods.
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