.40 kg klr fork springs in my KDX forks?

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trail70
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.40 kg klr fork springs in my KDX forks?

Post by trail70 »

First post here in KDX land. The KDX has always interested me but Ive never had a chance to ride or own one. Last week everything changed. Ive owned XR's DR's DRz's KLR's and after 15 yrs of thumpers I have finally made the switch to a smoker. Here's she is...my new to me low hour '99 model 220 found on CL Phoenix. Bone stock and unmolested. I swear the owner teared up when it was time to load it in my truck.
Image
So on to my question - I have some stock .40 kg KLR650 springs (next gen klr with 41mm forks) that Id like to drop in the KDX forks. Of course I'd adjust spacer/spring length to match the oem setup, any reason I couldn't use these springs?
Thanks!
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Re: .40 kg klr fork springs in my KDX forks?

Post by kawagumby »

I can understand that owners regret...

If they're the same diameter, they'll work. I've used springs from Hondas, Yamahas and anything else I"ve had around ...shorter ones, longer ones...they all work once dialed in preload-wise.

Nice bike...be sure and swap the stock piston out for an aftermarket... the stock ones can self-destruct without warning or even having much time on them.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
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trail70
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Re: .40 kg klr fork springs in my KDX forks?

Post by trail70 »

I have a wiseco kit setting on the bench. The klr springs are all wrong as it turns out. Diameter is too small and the length is a lot shorter. I pulled the forks off today to have a look. The thing that confuses me now is there's no comp clicker. The spec I read for the 99 220r shows adjustable compression damping. The screw in the cap I thought was the clicker is a bleeder. Did I miss something?
*Update* Found the comp clicker. Doh. covered in dirt, right where it should be on the bottom... I'm off to a good start :roll:
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Re: .40 kg klr fork springs in my KDX forks?

Post by trail70 »

Just thought I'd post up here about my fork spring solution. I found some oem DR650 (.40kg'ish) progressive springs on ebay for $25. I was a little hesitant because I've always heard you gotta use a straight rate spring to get a good set up and I've had pretty good success in the past with them. Anyway I put them in a couple weeks ago - the DR650 spring length is about 1/2" shorter than the KDX so I used some washers to match them with the stocker's length. Stayed with 5W oil at 95mm. I finally got out for a ride yesterday - the temps dipped below 100 in AZ so I thought I'd better take advantage of the "cool" weather. The forks worked great! Plush, firm, didn't deflect off the rocks. The bike is nicely balanced now and doesn't dive like it did with the stock springs. If anyone has considered using these springs I'd say go for it!
https://www.youtube.com/watch?v=pVhkuC4Zauc
Last edited by trail70 on 11:31 pm Sep 05 2014, edited 1 time in total.
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Re: .40 kg klr fork springs in my KDX forks?

Post by KDXGarage »

Congratulations on the bike, as well as getting some better fork springs in there.
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Re: .40 kg klr fork springs in my KDX forks?

Post by kawabunga »

I just installed .40 springs from an XR 400 in my 2000 KDX.
All I can say is that my spring rates are right on the money.
I weigh 190 with gear.
I find the bike can be ridden much faster with both ends balanced.
Matched the OEM spring and spacer length-Longer springs, with shorter spacers.
Upped my compression clickers to -7.
reviving old war-horse.
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Re: .40 kg klr fork springs in my KDX forks?

Post by kawabunga »

The bike worked good on the 5 acre backyard track, but was very harsh and deflecting.
in the woods.
I will do the shim stock mod, and reduce preload.
Better fore and aft balance is very worthwhile, but the next weakest link has been
revealed.
reviving old war-horse.
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.40 kg klr fork springs in my KDX forks?

Post by BamBam »

Just bought a set of .40kg fork springs from FRP to adjust for my weight (with new oil) but I have never installed anything like this before. Any tips tricks I should be aware of? How simple is this task, and how long should I figure for a free block of time to do it right? Any special tools? Any help is appreciated !!
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Re: .40 kg klr fork springs in my KDX forks?

Post by KDXGarage »

Just be sure to set the preload correctly.
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Re: .40 kg klr fork springs in my KDX forks?

Post by bufftester »

I'd give yourself an hour, but it really is about a 15 minute job. Loosen the upper triple clamp bolts, remove the fork cap from the tube and the damper rod, remove the washer and spacer and spring. Reassembly is reverse. No special tools other than a 30mm socket for the fork cap. Service manual has all the torque values.
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.40 kg klr fork springs in my KDX forks?

Post by BamBam »

Since I bought this bike used, and its a 1997 - I thought it wise to change the fork oil at the same time. So I guess that means taking the fork tubes off to pour old oil out to get new oil in? No drain plug as I understand it. Filling back with 7.5wt oil to 100mm from top.

And if I am doing all that, I read about the shim/stack mod so figure I should include that task at the same time. One big front suspension mission all at once. Is this still a single afternoon of wrenching?

Question on the measuring for correct preload... the thread on that doesn't have pictures anymore, so I don't really understand the components stacked to measure against some overall length. Would another way to approach this be to consider the stock spacer as giving 38mm of preload, and I want to get to say 10mm.... if the new and old springs are the same length all I need to do is cut 28mm off the stock spacer? And if the new and old springs are different length, then adjust that math accordingly? (*does the shim stack adjustment above change preload spacer length??)

When figuring preload... does rider weight come into play? Meaning, if I am 200lbs and using a .40 spring for the range of 180-200lb rider, do I want to lean more towards 10mm instead of 4mm for preload because I am on the heavier side of the rider weight based on spring range?
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Re: .40 kg klr fork springs in my KDX forks?

Post by KDXGarage »

I suggest 5 weight oil.

Be careful when filing the peening off the base valves.

Measure twice, cut once.

Shim stack adjustment has nothing to do with preload.

Going with stiffer springs would have to do with higher rider weight, not the preload.

Hopefully, you do not weigh 200 pounds and are going with .40 rate?? I hope that is just a hypothetical question.
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Re: .40 kg klr fork springs in my KDX forks?

Post by bufftester »

Preload is used for setting proper sag in the suspension, so rider weight is a factor, but so is the spring. There is no set number, it's a rider preference thing. You don't need to cut the OEM spacer, 1" pvc works well and has been used for years. Easy to cut and change.
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Re: .40 kg klr fork springs in my KDX forks?

Post by KDXGarage »

Good point, go with the PVC, then you can look once and cut twice for a lot less pain than the OEM metal spacer. :razz:
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Re: .40 kg klr fork springs in my KDX forks?

Post by BamBam »

Jason - according to the Fredette KDXposed page, he recommends a.40 rate spring is for riders 190lbs thru 220lbs. I also told him to send me the fork oil I would need, and that arrived as 7.5wt. With those combined, what badness might happen is a less than hypothetical way?
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Re: .40 kg klr fork springs in my KDX forks?

Post by KDXGarage »

It will be good. I think it could be better.
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Re: .40 kg klr fork springs in my KDX forks?

Post by BamBam »

If I do a quickie first pass on the forks tomorrow, and just change springs from the top without changing oil or taking forks off... is there a way to determine preload spacer size?

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Re: .40 kg klr fork springs in my KDX forks?

Post by KDXGarage »

Yes. This might help. http://www.racetech.com/html_files/preload.htm

If you are in a hurry, just use the stock spacer. You can get a feel for the stock preload and then do it again with a modern amount of preload and compare.
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Re: .40 kg klr fork springs in my KDX forks?

Post by KDXGarage »

If you open the forks up and take the stock spacers out, there will be a gap when it is reassembled. Cut a 1" PVC pipe to take up this gap. If you were to cut it to where it was JUST flush with the other parts, this would be zero preload. Any additional length beyond this is going to make the spring compress. How much longer you make the PVC spacer is going to be how many mm of preload the spring will have on it.
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Re: .40 kg klr fork springs in my KDX forks?

Post by BamBam »

Jason - in that RaceTech preload diagram you shared, would a KDX be going by the "back in the day" preload measurement or the modern "actual" preload that comes as a result of the "long soft top out springs" when you guys refer to the 4mm-10mm ideal range for preload??

Also - what is that little flat head screw for in the center of fork caps?
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