How are new USD forks supposed to feel?

Questions and comments about converting to beefier forks..
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wanaride
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How are new USD forks supposed to feel?

Post by wanaride »

I got tired of hijacking another thread, so I thought I would start another one instead.

2003 KDX200 with NEW 2004 KX125 front end. Stock springs and valving in the KX forks. The triple tree bolt torque value was 14ft-lbs. I used the assembly procedure on the TWMX site that was written by a Kawasaki/Pro Circuit mechanic (headset maintenance); I think I found the link on this site.

Sorry Vince, I'm ignorant but I'm learning. I've only got seat time with two sets of forks, the original OEM KDX forks and these new KX forks. I wouldn't know the difference between stiction and stiffness if one of them bit me on the ass. Care to enlighten me?? :prayer:

I'm 220# w/o gear. How are new KX/USD forks supposed to feel? How will they feel after they are "dialed in"??
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Indawoods
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Post by Indawoods »

Go down to your dealer and sit on a new KX... notice how the frontend reacts to you sitting on it.... put the brake on, move it up and down a few times.... get off of it. Sit on it again and note how it reacts to you sitting on it.


Now,
Go home and do the same to your bike and compare notes.

I do not believe anyone has gotten satisfactory performance out of their KX forks with a 14lbs torque setting. Mine is at 11lbs... this is where I hit Zen on sensitivity for fork reaction. Others have gotten the same results...between 11 and 12 foot lbs torque.
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Post by scheckaet »

where did you set your clickers?
what's your oil level?
do you know your shim stack configuration?

It's easy even when you follow some pro advice to make the front stick. If it were me, I'd make everything loose and start again.
I doubt the stock spring would be too stiff for you, I'm 170 and my stock spring fells fine.

Another thing, are you sure it's not the rear that's messed up? I know, sounds dumb but mine was so unbalanced after the conversion that I thought my shock was shot. I'm actually playing with the clicker in the rear and it made a big improvement.
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Post by krazyinski »

Proper installation of front forks
If your front forks are too harsh in the mid stroke after getting them back from having them worked on. Often times, the problem is not the work done by the tuner, but improper installation of the forks by the rider when he/she gets them back. Following the procedure below can help you to get your forks installed correctly the first time and avoid an embarrassing phone call to the tuner.

1. Put each fork up into the triple clamp and measure from the top of the fork to the top of the upper triple clamp and make sure both forks are the same distance.

2. Torque the triple clamp bolts to the manufacturer specifications. Remember, the lower triple clamp bolts should not be as tight as the upper bolts. If you over tighten them it will cause the bushings to bind as the fork is compressed.

3. Install the front tire axle bolt and torque.

4. Make sure the axle pinch bolts are loose. Take the bike off of the stand and push on the handlebars several times so the forks compress to mid-stroke. Place the bike back on stand and spin front tire and hit front brake several times.

5. Torque pinch bolts and you should be ready to go ride!
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Post by skipro3 »

I don't know the 2004 KX front assy, but here are a few points that will cause stiffness or stiction;

1. Axle to fork alignment; Loosen the fork t-clamp pinch bolts so the axle will cleanly slide into the forks, without the wheel, in perfect alignment. If one fork leg is higher or out of rotation to the plane of the axle, things will bind.
This also gets both fork legs exactly the right height in the t-clamps without just eyeballing it.

2. Assemble wheel with the axle to the forks while making sure the tightening action of torquing down the axle nut does not cause the fork legs to be drawn together. Changing the span between fork legs as you tighten the axle will cause stiction. Usually you can clamp the axle down to each fork leg first, then tighten the axle nut, or one side of the axle floats as you tighten down the axle nut, then you pinch the axle to the fork leg.

3. tighten upper and lower t-clamps to 10 ft lbs. starting with the upper clamp.

4. with the bike off the stand, bounce the front end up and down by standing next to the bike, foot on peg and hands on bars, no front brake. Forks should easily go up and down without the bike wanting to roll forward or having to overcome some sort of initial resistance (stiction). If there is resistance, then loosen axle nuts and axle pinch bolts, bounce again while applying and releasing front brake to settle and align the front rotor.

5. Tighten up the axle clamps and torque the front axle and try the bounce test again.

6. torque top clamps to 14 ft lbs and bounce again.

7. torque bottom clamps 1 ft lbs at a time and bounce. When you feel resistance (stiction) you've tightened too much. Back off 1 ft. lb. I had mine at 11 ft. lbs.
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Post by KDXer »

The easiest way for me to notice it on my forks was to stand beside the bike off its stand, now push some of your weight down on the footpeg (gentle bouncing makes it more obvious). With stiction present the back of the bike sort of bobbed and the front didn't really move at all, with no stiction present the whole bike bobbed evenly. :partyman:
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Post by bradf »

Check the fork free sag. It can be utilized here as an indicator if there is stiction. If there is no stiction the free sag should be between 15-30 mm. Loosen all the lower clamps and check. This will eliminate any possibility of the clamps being too tight. If the sag is correct, re-tighten the lower clamps and check again. The forks should settle in at the same sag distance.
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Post by Jeb »

I used this method to get things "aligned" (I borrowed it from brucessuspension.com); a variation on krazyinski's method. I think it covers the axle-to-fork angles:

* Put the left fork (caliper side) into the triples with the fork at the desired height. Torque the triple pinch bolts to "spec", spec being the 11-12 ft-lb torque suggested. It DOES make a difference.

* Place the right fork into the triples and lightly tighten one of the triple clamp pinch bolts (you may not even need to tighten anything - my triples, for example, held the fork in place on their own).

* Install the axle only - no spacers, nothing - with the nut very lightly tightened.

* Rotate the axle with your hand between the left and right fork. Continue to rotate but slide the right (loosely-held) fork in the triple clamps in small increments. You want the right fork located where the axle turns most freely.

* Torque the triple clamp pinch bolts for the right fork to "spec".

* Install wheel, brakes, axle/axle nut. Torque the left-fork axle pinch nuts to spec (leave the right-fork axle pinch nuts loose).

* Work the forks deep into their travel several times.

* Now, torque the right-fork axle pinch nuts to spec.

I used KDXer's version of checking stiction when I first put the forks on - I ended up with 135 in-lb of torque on my lower bolts!! Works great!!

I don't know what the difference in feel is between the typical base-valve shim stack for mx and removing several of the big shims because I removed 6 out of 10 of the 24mm shims when I had the forks apart for servicing.

***EDIT*** Changed 135 in-lb of torque on my UPPER bolts to LOWER bolts.
Last edited by Jeb on 05:07 am Apr 05 2007, edited 1 time in total.
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Post by wanaride »

Man, there is SO much to this stuff that I don't know. I am so clueless; I just torqued those triple clamp bolts down, in the order prescribed in the TWMX article, to the listed values without any awareness of the problems that could happen. Many thanks to ALL of you for taking the time to help me out with this, I REALLY appreciate it. :prayer: :prayer:

My plan:
- research and perform base valve shim stack modification.
- print out this thread and reassemble the front end.

I've read that the nut on top of the BV is 'staked'. What is the best way to get rid of this stake? A Dremel mototool?

Realistically, do you think the BV shim stack mod (and proper front end reassembly) will be enough? How many of you have done other mods to your USD forks (i.e. midvalve)? My forks are supposed to be new so they shouldn't need a rebuild.

Thanks again!!! :supz:
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Post by Indawoods »

All that should be enough... don't fret the mid-valve stuff if you can't figure it out... Race-tech makes a kit to replace the midvalve if you want.... IMHO... midvalve is a waste in the woods so there is no need for it.... mine is still harsh and I will address it next month. Just too many irons in the fire right now or else I would run through it with you as I do it. I will write up a how-to when I do though.

As stated...you will want to get the shock evened out for your new frontend too... they do work together. I think you wrote that you were over 200#'s... if so...a 5.2 spring may be in order.

Keep us updated! :supz:
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Post by Jeb »

>|<>QBB<
wanaride wrote: . . . I've read that the nut on top of the BV is 'staked'. What is the best way to get rid of this stake? A Dremel mototool?
It's peened. I copied this out of the Kayaba service "sticky" that Inda has so graciously supplied:

"Before removing the nut on the compression valve, the threads above the nut must be filed off. Use a file and file lightly the end of the threads until they are flush with the top of the nut."

The compression valve referred to is the base valve.

You might want to read through the html pasted as a link in the Kayaba service sticky for more details.
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Post by Indawoods »

a 6mm fluted bit is used by pro's to remove the stake metal, you can buy them but unless you plan on doing a bunch of base valves, the cost is prohibited. a good file is all you really need.... but plan on taking your time because if you don't get the material completely removed.... you can ruin the threads and your base valve will be ruined.
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Post by kawagumby »

I guess I'm the only one who just unscrews them, stakes and all. Never had a problem.
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Post by wanaride »

Thanks guys. I wasn't sure if that Kayaba link applied to my forks, now I know it does (says so in the first paragraph, duh :oops: ).

I put a 5.2kg/mm spring on the back some time ago so I should be good there. I won't worry about the midvalve for now. When I get the BV out I should know whether I can just unscrew them "stakes and all" or go the file route.

Is there a commonly accepted shim stack configuration to use as a starting point?
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Post by Indawoods »

I think it is more of a judgement call... if there is 12 24's in there... I think it would be pretty safe to remove 4 of them.... at least that's where I would start.
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Post by krazyinski »

>|<>QBB<
kawagumby wrote:I guess I'm the only one who just unscrews them, stakes and all. Never had a problem.


your not the only one done it 4 times my self.

I think it is more of a judgement call... if there is 12 24's in there... I think it would be pretty safe to remove 4 of them.... at least that's where I would start.


I removed all but 3 24's and thats good for me. next time the forks are a leaking I will jack with the mid valve.
2000 KDX220 FRP Ported,plated cylinder,milled head, FRP bored carb, V force 3 reeds, FMF desert pipe, 10oz FWW, 98 KX forks and oem shock re valved by Pro Action, hyd clutch, fastway pegs, tall seat foam, gripper cover, 29" CRhigh mini bars, Cycra brush gaurds.
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