Going price for KX forks

Questions and comments about converting to beefier forks..
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pdiddy
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Going price for KX forks

Post by pdiddy »

So I am looking into doing a KX fork swap on my 04 KDX 200 and have been doing a bunch of reading and searching on here, but I not sure what the price range is. I want forks in good working order, but I don't want to over pay, if that makes sense. For example these 2001 KX250 forks have a buy it now price of $170.

But these 2001 KX125 forks have a buy it now price of $200.

Are the $200 forks over priced? Or should I be skeptical of the quality of the $170 forks? Also, would it be worth the $350 that newer KXF forks are going for to get those over the older KX forks?

Obviously, before buying any forks I would want to know how they are setup and when they were last serviced. But I would like to get a better understanding of price range. Thanks!
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Post by Indawoods »

All sounds good to me. One thing you might consider is that the KX 250 forks will have heavier springs in them that the KX 125 forks. If you have to respring either way... it will cost you money.

I weigh about 210 and have .43 springs in my 03 KX125 forks and they are perfect. (remember this is for woods application)
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Post by pdiddy »

I am 150lbs (yeah, I know I am skinny) and an intermediate woods rider, so the 125 forks would probably be a better option for me then.

Thoughts on what weight springs I should be looking at? I know the KDX forks are soft, as I am riding them almost on the fully hardest compression setting. 18 out of 20 clicks, if I recall correctly.
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Post by zomby woof »

KX125 forks will have springs around .40-.42, and you will need something in the .38 range.
The KX250's will be only slightly heavier, and are otherwise the same fork. $200 is not too much money to pay for a set of high quality forks, if you think about it.
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Post by pdiddy »

Per the Race Tech website, 01 KX 125 forks have a stock spring rate of .41 kg/mm. The calculator on the Race Tech website suggests .40 kg/mm springs for my wight and woods riding. Is there really that much of a difference between the two springs? .01kg/mm seems like a very small difference.

.01kg/mm over 310mm of travel is 3.1kg, or about 7lbs. If I understand spring rates correctly, that means it takes 7 additional lbs of force to fully compress the .41kg/mm springs over the .40kg/mm springs. Or am I off base with my understanding/calculation?
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Post by zomby woof »

There isn't enough difference between .4, and .41 to notice, but .4 is too heavy for your weight in the woods.
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Post by IdahoCharley »

>|<>QBB<
pdiddy wrote:Per the Race Tech website, 01 KX 125 forks have a stock spring rate of .41 kg/mm. The calculator on the Race Tech website suggests .40 kg/mm springs for my wight and woods riding. Is there really that much of a difference between the two springs? .01kg/mm seems like a very small difference.

.01kg/mm over 310mm of travel is 3.1kg, or about 7lbs. If I understand spring rates correctly, that means it takes 7 additional lbs of force to fully compress the .41kg/mm springs over the .40kg/mm springs. Or am I off base with my understanding/calculation?
That would be 14 lbs considering both springs and would have you coming into the air-spring a little sooner. You could put on some weight over the holidays to compensate :partyman: :grin: .

Splitting hairs really between the two spring rates - changes to fork action to compensate for slightly off spring rates can be moderated by spring pre-load, oil level, oil visocity and valving changes. Overall fork tuning does dictate having a spring rate based upon you weight and ability and riding but fine tuning the rest of the fork's components is going to be required in order to get the best fork action. It all has to work together. My .02.
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Post by pdiddy »

That would be 14 lbs considering both springs and would have you coming into the air-spring a little sooner. You could put on some weight over the holidays to compensate :partyman: :grin: .

Splitting hairs really between the two spring rates - changes to fork action to compensate for slightly off spring rates can be moderated by spring pre-load, oil level, oil visocity and valving changes. Overall fork tuning does dictate having a spring rate based upon you weight and ability and riding but fine tuning the rest of the fork's components is going to be required in order to get the best fork action. It all has to work together. My .02.
I have been trying to gain weight for about 10 years, without much success. As strange as it sounds, its true. I have the metabolism of a humming bird. :shock:

Thanks for clarifying and correcting my calculation. It sounds from all the searching I have been doing that .38kg/mm would be a better choice.
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Post by canyncarvr »

RaceTech's recommendations on spring rates are always on the high side, seems to me.

.38's worked fine for me..@ 180#. They certainly won't be too light for 150#.

One of those links is gone...maybe that was you?

Re: 'Obviously, before buying any forks I would want to know how they are setup and when they were last serviced.'

I can answer that for 'ya! If you asked, 'I want to use these for a woods bike, how are they setup and when were they last serviced?' the answer would be:
Fork Seller wrote:These forks are setup perfectly for woods riding..and have been regularly serviced. They're in GREAT shape!

Along with the forks remember you'll need some other stuff..a wheel, rotor, axle, spacers, triple clamps....

Can't say about your KXF question. There is a large difference advancement-wise between the OEM KDX forks and an KX fork. Between eight year old KX and newer KXF? I have no idea.

A more pertinent question I think would be, 'Will a KDX stem fit a lower KXF clamp?' The reason KX forks are popular to swap in is 'cuz it's pretty easy to do. If you have to have a stem made to fit the KXF clamp that will take the KDX bearings..there's more money spent.

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Post by 3dhunt »

pdiddy, I just completed this project on my '03 220R. I too am 150# and am an intermediate woods rider. I purchased a set of KX 250 forks from a '99 model and had to purchase new springs to fit my weight. I had the forks professionally built by a well respected shop in Oklahoma City. He installed .40's with oil height set at 110 and they are amazing. Cost of the forks ran me $180 with another $100 for springs. The 125 forks you found would be real close to right I think, plus if that was the set that had the guides for the brake line and fork guards thats a plus also.
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Post by zomby woof »

RaceTech's recommendations on spring rates are always on the high side, seems to me.
I would tend to agree, but maybe the problem isn't them. Maybe we're too slow :mrgreen:
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Post by river »

>|<>QBB<
pdiddy wrote:Per the Race Tech website, 01 KX 125 forks have a stock spring rate of .41 kg/mm. The calculator on the Race Tech website suggests .40 kg/mm springs for my wight and woods riding. Is there really that much of a difference between the two springs? .01kg/mm seems like a very small difference.

.01kg/mm over 310mm of travel is 3.1kg, or about 7lbs. If I understand spring rates correctly, that means it takes 7 additional lbs of force to fully compress the .41kg/mm springs over the .40kg/mm springs. Or am I off base with my understanding/calculation?
How much can you compensate for the spring with oil viscosity and height?

I am 230, and just got KX forks sprung for a 175# rider with gold valves. Wondering what I'm going to need to do. I am to new to know what kind of rider to call myself. I live in the desert but some of the trail surfaces I ride looks a lot like the surfaces on the woods riding videos on Youtube.
I'm not dodging trees but that doesn't seem it would be a fork issue.
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