Conversion fork length and revalve questions

G22inSC · Post by **G22inSC** » 06:26 pm Nov 09 2014

I completed my KX front end conversion a couple years ago and at the time just tried to slide the forks as far up as I could attempting to keep the original KDX geometry. I knew from measurements at the time that the front end was still too tall. Long story short, I had some extra time today so I pulled the old KDX front end out from under the house. I again measured what I currently had with the KX forks and then re-installed the KDX forks and took the same measurements. This is what I currently have:

KDX axle diameter of 0.589" and KX axle diameter of 0.791"

KDX - length from center of front axle to bottom edge of frame neck steering stop - 27.125 + 0.294 = 27.419"

KX - length from center of front axle to bottom edge of frame neck steering stop - 27.375 + 0.395 = 27.770" (forks raised 13mm in triple tree)

KX - length from center of front axle to bottom edge of frame neck steering stop - 27.875 + 0.395 = 28.270" (forks mounted at OE "scribe" line)

The max I can raise the bars is 13mm before I start hitting the bottom of the handlebars. I have a difference of 0.851" (21.6mm) when both forks are mounted where they would come from the factory. I believe I am going to have the front forks shortened by 0.750" and revalved to match the rear shock for a "C" level harescramble racer. I can then raise them 0.101" in the triple trees to match the OE KDX geometry and have a little room left to raise or lower them for further tuning if desired. Has anyone else measured their front end with around a 2000 model KX and come up with the same approximate numbers? Do these numbers seem sound such that it would lead to the correct KDX geometry?

Now what about a revalve? I am thinking about sending my KX forks and shock to Factory Connection to have them revalved to work in unison and have the correct springs installed for my weight. Has anyone had any first hand experience with Factory Connection? Does anyone recommend somewhere else better that is familiar with the KX fork setup with a KDX shock? Open to any opinions.

Post by **KDXGarage** » 01:09 am Nov 10 2014

Thank you for posting the measurements.

Be sure to read up / ask FC about changing the o-ring to a spring on the midvalve. Also ask about midvalve float options.

G22inSC · Post by **G22inSC** » 06:26 am Nov 10 2014

Please explain. I just remember hearing people talk about removing the midvalve.

adam728 · Post by **adam728** » 08:41 am Nov 10 2014

Race Tech pushes to eliminate the mid-valve and just have the base valve handle all the tuning. I don't agree with this, as you are throwing out a strong tool in suspension tuning. It simplifies things for the home tuner, but doesn't make performance better. Although a more archaic system setup correctly is better than a more advanced system that's not even in the ballpark.

Many fork setups use a tiny coil spring on the mid-valve that allows the whole stack to float, allowing bleed before actually engaging any damping. Functions similar to a bleed shim/bleed hole. If a bike has no bleed or float, then the mid-valve stack will be very soft, or it will be extremely harsh in small chop. Adding float will then require significant stack stiffening to keep it from falling through the stroke on quick bumps.

Tedh98 · Post by **Tedh98** » 04:30 pm Nov 10 2014

adam728 wrote:Race Tech pushes to eliminate the mid-valve and just have the base valve handle all the tuning. I don't agree with this, as you are throwing out a strong tool in suspension tuning. It simplifies things for the home tuner, but doesn't make performance better. Although a more archaic system setup correctly is better than a more advanced system that's not even in the ballpark.

+1 on this.

You just need to tune the MV correctly for your type of riding.

B737driver · Post by **B737driver** » 06:08 pm Nov 10 2014

Had my forks internally shortened by 3/4" by the local suspension guru. Although I did not have the exact measurements, this was the consensus on the forum as well as his "educated guess ". I am very happy with the results. Forks now are roughly 1/8" above the clamps and it feels right.

By the way, some warned about the loss of travel. I get that, but have not noticed it thus far. No triples in my future anyway.

G22inSC · Post by **G22inSC** » 06:16 pm Nov 10 2014

B737driver wrote:Had my forks internally shortened by 3/4" by the local suspension guru. Although I did not have the exact measurements, this was the consensus on the forum as well as his "educated guess ". I am very happy with the results. Forks now are roughly 1/8" above the clamps and it feels right.

That seems to coincide with my numbers very closely. I would have 0.101" above the clamps vs your 0.125". Probably not going to get much closer than that. Had a little spare time today so I put together a pdf file for future reference.

larger pic in gallery

6 Riders · Post by **6 Riders** » 08:06 pm Nov 10 2014

The forks need to be shortened, there is no doubt about this. If you are shipping forks, I'd like to recomend LT Racing in Washington. He does great work and is honest (which is OVERLY important to me). His prices are very fare also.

LT Racing's link http://www.ltracing.com/index.html
Also check out what he says about lowering your forks. YES you will loose travel equal to the amount of the lowering BUT you will have the same amount of travel that you had before the conversion....so the amount that your KDX is made for. Here's the link http://www.ltracing.com/html/suspension ... onLowering.

Post by **KDXGarage** » 01:58 am Nov 11 2014

Those forks have an o-ring instead of a spring on the midvalve.

Don't throw out the midvalve.

If aking it simpler was the way to go, we would all be on damper rod forks.

Tedh98 · Post by **Tedh98** » 06:29 am Nov 11 2014

G22inSC wrote:Now what about a revalve? I am thinking about sending my KX forks and shock to Factory Connection to have them revalved to work in unison and have the correct springs installed for my weight. Has anyone had any first hand experience with Factory Connection? Does anyone recommend somewhere else better that is familiar with the KX fork setup with a KDX shock? Open to any opinions.

I don't have any experience with FC. I've done my own revalves.

I saw in another thread that you mentioned a shop close to you. If they have a good reputation, I would deal with the local shop over any place that you have to ship your stuff. It should be faster and cheaper if you aren't having to ship forks and shocks (especially if it takes more than one try to get it right - which is fairly common). And the local guys should know the exact terrain you are riding on.

G22inSC · Post by **G22inSC** » 07:46 am Nov 11 2014

That is the problem...I can't really find any reputation either way. I only know of one person (on-line) that has had suspension work by the local shop (Pro Motion in Greer, SC). I would really like to stay local for the ease of it all but don't know about taking the gamble. Factory Connection is known and somewhat offers lifetime revalves if that was ever needed in the future. WER is also possible and I believe they are more off-road biased which is a plus for my situation. I don't know much at all about suspension work which is why I have never attempted any. Is there that much difference between the different outfits? Would you'll take the unknown local gamble versus the known shipping options?

B737driver · Post by **B737driver** » 11:40 am Nov 11 2014

Just to give you an idea.....it cost me around $350.00 to have the forks completely rebuilt, revalved for my weight, lowered, and new push button fork bleeders. Not sure what others charge. Lucky and Ben at http://www.lcsracing.com are great to deal with. I was willing to pay the $ for piece of mind from a reputable company. FWIW

royadams · Post by **royadams** » 01:00 pm Nov 11 2014

Maybe we can get together to ride and you can check out my suspension and see if you care for promotion set up.

G22inSC · Post by **G22inSC** » 08:44 am Nov 12 2014

royadams - PM sent

G22inSC · Post by **G22inSC** » 03:28 pm Apr 26 2015

Forks are now done. Got worked over locally and shortened at the same time. I requested they be shortened by 0.750" but I don't think they ended up that number shorter. Took a quick measurement of one of the fork legs before dropping them off but I can't find the notes where I wrote the number down. I got them mounted up today and figured by measurements that with the forks mounted 6mm higher than the "scribe line" I have the same OE KDX geometry.

My previous numbers were:
KDX - length from center of front axle to bottom edge of frame neck steering stop - 27.125 + 0.294 = 27.419"

Current numbers are:
KX - length from center of front axle to bottom edge of frame neck steering stop - 27.062 + 0.395 = 27.457 (forks mounted at 6mm higher than the "scribe line")

That gives me a front end that is just under 1mm longer than the OE KDX geometry. It may slow the turning a minuscule amount, but could also help the high speed stability.

larger pic in gallery

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