Ride Report - Modified Forks

[andrew]

I have been trying to make my stock forks better, and had already put in .41 XR400 springs. They were still too harsh in the first part of the stroke, and I was thinking maybe the springs were too heavy. Then I posted a couple of questions on the Suspension Q&Q forum, and got to researching shim stacks and the like.

To cut a long story short, I pulled the valves out and removed two of the 10 shims, effectively reducing high speed compression dampning by 20%. What a difference! The forks are now a lot more plush in the first part of the stroke, and soak up those rocks and roots that used to deflect my front wheel and give me forearm pump trying to keep it in a straight line. The .41 springs still sit nice and high and don't dive too much in the sand, and take the big hits from jumps and stuff in their stride. This has been the best mod I've done since upgrading the springs, and best of all it was FREE! :)

OK, so it's still not progressive dampning like you'll get from gold valves, but I haven't got the cash to spend on gold valves at this point in time, and after this I may not even bother saving up. I can still feel a spike in the midrange, but the forks are so unbelievably better on the rocks and stuff that I can overlook that transition from plush to full dampning. I can ride faster and with more confidence over the rocks, and that's what I needed.

Sorry for going on about it, I just wanted to share this revelation with my fellow KDX er's, especially those who are looking for a free mods.

Cheers,
Andrew

 

[layoutd]

when you say you removed 2 of the 10 shims, could you be a little more descriptive for those that may be interested in doing the poor mans revalve.

 

[andrew]

When you pull the valve out of the bottom of the fork (and you don't need to dismantle it to do this), you will see a nut on the top. Under that nut is like a cage, then a spring, then the shims. You will need to file down the crimping (if that is the correct word) on the thread, unscrew the nut, remove the assembly hoding in the shims, take two out then replace it all. Without a photo or decent diagram it is a bit hard to explain, but once you see it in front of you all will become clear. It really is a basic setup, the first one took a little while because I didn't really know what I was doing, but the second one took about 15 minutes once the fork was removed from the triple clamps. The only thing to watch is that crimping or spiking of the top of the thread, to stop the nut from being removed. The nut is not hard to get off, but the top needs to be cleaned up with a file in order to slide the rest of the components off the shaft. Be sure to clean it all up to remove filings before reassembly.

Good luck !

Andrew

PS, mine's a '96 model.

 

[XRIowa]

Hey I am in the process of the exact same mod I just pulled my Eibach springs out of my grenaded XR 4 and would love any help anyone could give me I am kinda a newbie to suspension work so any help you could give me would be great do you have any pics that might be of help could you maybe e mail them???
Thanks
KDXRIowa

 

[andrew]

Sorry mate, I didn't think to take any pictures :bang: I was only experimenting and was surprised it turned out so well. I gave a pretty good description (I think ) so have a go, you may surprise yourself. I am by no means an expert myself ! In fact, just keep in mind the definition of expert: X is an unknown quanity, and a spurt is a drip under pressure. ;)

 

[XRIowa]

OK what I was wondering is I have read you need a piece of PVC to put in there is that because the XR fork is shorter to even it up or what?? Anything else I should know?

 

[andrew]

I think you are talking about spring pre-load spacers, which is up the top of the fork. I am referring to the compression damping valve at the bottom of the fork. If you look at the bottom of your fork you ill see a large hex head. Inside this should be a rubber grommet, and underneath that grommet is the compression damping clicker (small flat tip slot). If you were to undo the whole assembly using a 14mm Hex head, the entire compression damping valve would come out, and this contains the shims that restrict oil flow thus providing compression damping.

The PVC spacers you are referring to will be required because the XR spring is a lot longer than the KDX spring; therefore the KDX spacers (metal) would be too long, or if used would provide way too much spring preload. As a guide, the PVC spacers I put in with my 512mm Eibach springs was about 40mm. (stock KDX spring was about 187mm I think, and stock XR400 springs may have been up to 530mm I remember reading, so you need to set your preload spacer length according to what springs are going in. You can do a search for 'preload' for more specific info.) It is possible to cut down your stock spacers to the correct length, but PVC is easier.

Cheers,
Andrew