Do i need to revalve/shim?

Questions and comments about converting to beefier forks..
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layoutd
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Do i need to revalve/shim?

Post by layoutd »

I have recently obtained a set of 1996 kx 250 forks for my KDX. do i need to rework the valves and shims or can i just redo the seals and change the oil and then put them on the bike? will this still be too harsh for the woods? i weigh 160 lbs. can i just adjust clickers?

i know that a revalve would be great, but it is a fairly expensive operation from what i have gathered.
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Post by Indawoods »

If your forks were set up for a guy 250#... then yeah... they will need to be revalved. What rate of springs are in 'em?
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Post by KDXGarage »

You may want to just take a "try it and see" approach. If you just ride them for a while, you will know what to tell your tuner. If you just send them off, then it will be you and him making a "best guess" as to what you need.

I looked on the Race Tech site, and the stock spring rate should be good for trail riding. That doesn't mean that they have the stock springs stil in them, of course.

If someone uses the stock base valves, then adding/removing/replacing some shims on the base valve would not, OK!, SHOULD NOT, cost much. Making adjustments to the midvalve assembly would be more involved.

Again, just ride them for a while so you will know what, if anything needs to be improved.

The KDX forks use an old technology base valve design that can definitely benefit from being replaced with a Race Tech Gold Valve / Racing Suspension Products base valve kit / etc., but I wouldn't be in a rush to replace it on the USD KX forks, however. I would suggest that IF you and/or your tuner find that you have adjusted everything you can and are still looking for more, THEN try to go for an aftermarket valve. No need to spend all the money up front. :grin:
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Post by layoutd »

cool, where is the spring rate marked on the spring? or is it?
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Post by skipro3 »

I don't think springs are marked anywhere to their rate. Brad worked out some method of using the bathroom scale to determine spring rate.

Best bet is Jason's advice: With good seals, correct oil and level, give them a try and see how they perform. Look for static and race sag and start playing with the clickers. Try the compression and rebound at the half-way point, then adjust the compression for full out: all the way soft. Then determine in which direction you prefer. I guarantee you, you won't be going more than half way in on the compression unless you're doing table top jumps and such. Also read those threads discussing the sticktion issues when torquing down the clamps and wheel. I have 1996 KX125 forks and the only difference I saw between yours and mine was spring rate. My 125's were way too soft for me at 190 lbs. I replaced them with .42 race tech springs. I also installed gold valves and reshimmed to woods riding. (Well, I didn't, but my fork mechanic did)

Good luck and keep us up to date with the install. Ask questions, we love to give advise as long as the beer is cold! :partyman:
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Post by KDXGarage »

My original post got deleted, so I will do a qucik summary.

Almost all fork springs do not come with the rate marked on them.

Be sure to at least check the oil level. The last set of forks I worked on had one leg with the oil level 8 inches too high. :shock: The guy who currently owned the forks bought it from a wannabe Mr. GoodWrench, apparently.
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Post by layoutd »

i do not have a front wheel yet to put them on the old KDX, so i am definitely going to rework them. since i am only 160# i would imagine that they are going to be too harsh for the woods. as far as big table tops and jumps, i may hit them, but my bike won't be more than a few inches off the dirt. :wink:

Hey Skipro, want to trade those 125 springs for my 250 springs?
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Post by skipro3 »

I don't think I kept them. I had my fork tuner install Race TEch springs and I don't think I kept the stock units. I'll look though, and if I find them,they are yours.
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Post by Indawoods »

WOW...

Check out the High and Low speed adjusters!

http://www.ebrperformance.com/pg3.htm
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Post by skipro3 »

I like my forks just the way they are. (Repeat over and over)
Dang you Inda, I'm broke right now stop it!!!!
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Post by layoutd »

so would these replace the gold valves, or could i buy these instead of gold valves?
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Post by Indawoods »

Replace... or instead... either one. Total adjustability! :supz:

In the past... low speed was only adjustable by changing your shim config... with these, you get it within range and can adjust it without tearing your forks apart to add or take out shims for changing conditions. Simply turn a screw!
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Post by canyncarvr »

re: Hi and Lo speed adjusters...

That is nothing more than a base valve...right? It is a Hi (piston/shims) and Lo (clicker) valve you thread into the bottom on the cartridge.

So...it's a whole lot better cuz.....why??


The HSC is externally adjustable? I can read their write-up and assume that is so...if I want to, to I can read the write-up to understand it does NOT...if I want to.

***edit**

OK..so I wrote it one hour, posted it in another...

What about rebound? That's in the cartridge.

Oh...and it is LSC is largely clicker and HSC is largely shim, right? We just went over that..but now I read it the opposite?
Inda wrote:...low speed was only adjustable by changing your shim config...
Last edited by canyncarvr on 01:08 pm Jul 19 2005, edited 3 times in total.

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Post by Indawoods »

Did you click on the link and see how it worked?

Image
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Post by canyncarvr »

No I did not.

But you did...so now I don't have to!

Thanks for the info!

Tell me how you like 'em!!!

Ski? On the way??? :wink:

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Post by Indawoods »

You know he is CC! :lol:
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Post by Indawoods »

canyncarvr wrote:What about rebound? That's in the cartridge.

Oh...and it is LSC is largely clicker and HSC is largely shim, right? We just went over that..but now I read it the opposite?
Inda wrote:...low speed was only adjustable by changing your shim config...
OK... HSC and LSC are the work of the shims... high speed being the small shims and low speed being the larger. The lower clicker only affects overall compression. With this snazzy little valve, it looks like you can elongate the stack or bring it closer together. From the pic (not all that high def) but the HSC is set by the lower Allen adjuster and the higher LSC is set by a straight blade screwdriver up through the HSC adjuster.

Yeah...that made sense! :blink:

Rebound is still set by the upper clickers...totally separate from this.
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Post by KDXGarage »

Total adjustability!
Actually, it would not quite be total adjustability. Between LSC (low speed compression) and HSC (high speed compression) is today's new word to further confuse us, MSC (yep, mid speed compression). That doodad won't do much for that. No cookie for those would elaborate on this detail. :mrgreen:

The HSC portion of the shim stack can use shims as wide as the LSC portion. For example, mine does.

I doubt the stack would be elongated. If you think about it in a "one shim flexes against another shim against another shim" sense, it would make sense that they would need to stay pressed against each other.

canyncarvr, on the rebound adjuster, it is a tapered needle in an orifice setup, similar to the pretty picture in the thread. There are shims and a piston on the end of the damper rod. Didn't you take your forks apart? If you didn't get that far into, I will send you a link for a bigger hammer, bigger screwdriver and different kinds of war plars to use on diassembling them. YES!! That is just a joke, and for those who have not figured it out yet, "war plars" are wire pliers. :grin:

layoutd, I still say you should just ride 'em first. As long as they seem to be in good mechanical condition and all (seals/bushings, no clanks or screeching sounds).
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Post by Indawoods »

What's next... semi-high-low-but-closer-to-the-low-side-compression? :blink:

Come on! Furgitboutit! I know I have a mid-valve... but most just disable it...so that tells me something right thur! :neutral:

I realize it won't physically elongate the stack... just move them further from each other... making it adjustable... proly why they made it. Still looks mighty snazzy to me... Ski should have a ride report by Sunday! :wink:
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Post by KDXGarage »

The suspension moves at all speeds, even SHLBCTTLS compression, as you suggested. :grin:

To use some cc lingo, "says me", the "disable the midvalve" notion is mostly a Race Tech idea. What is easier to get the customer at home working on his forks to do, revalve a midvalve or disable it and try to let the base valve handle it all? Joe Customer had a tough enough time trying to tune a base valve alone.

I doubt moving the stack from the needle would make much difference. I think the slight distance up the cartridge that the oil hits the valve wouldn't make a difference.

Look. Since I am such a nice guy, I will make you an offer to lower any confusion. If you need some forks that are easier to work on, I'll trade you a set of '87 KDX200 forks for your KX forks, and I won't even ask for any boot. :lol: :lol:
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