KYB shock revalving tips?

[Techfreak]

Hello Jeremy, hello guys!
At first please excuse my English. Hopefully you understand my questions.
I want to revalve my shock. I ride a ’97 YZ 125 and I have not the money to go to a tuner besides it’s really interesting. My Dealer should only fill my shock with new oil and nitrogen…
My shock feels too hard over small bumps. The rebound is fast enough but I think the Low-Speed-Compression is too much (compression adjuster all way out). So my shock don’t move trough acceleration bumps and so I lost very much traction. The rear end hops or bounce over these little bumps. On the other hand my shock feels to soft on fast rough sections with square edge bumps. There are so many big shims under the valve that I guess no oil can flow through it at low shaft speeds!?!
And I have no possibility to compare my valving with others, so I hope someone can help me with tips or a list of his own compression stack. (apart from linkage ratios, shock range of motion, used valve or piston …)
Much thanks ahead.
Compression Stack:
5x 0.15mm 40x12, (number, thickness, outer diameter in mm, inner diameter in mm)
7x 0.20mm 40x12,
1x 0.10mm 32x12,
1x 0.10mm 26x12,
1x 0.25mm 38x12,
1x 0.25mm 36x12,
1x 0.25mm 34x12,
1x 0.25mm 32x12,
1x 0.25mm 30x12,
1x 0.25mm 28x12,
1x 0.25mm 26x12,
1x 0.25mm 25x12,
1x 0.25mm 24x12

 

[marcusgunby]

Tech freak, first let me compliment you on your english, im afraid no one here normally gives shim stack settings as its really how they earn thier living,however your assesment of the LSC seems to be about right assuming you are a average weight.You could remove some LSC and replace the 0.25 shims on the HSC with 0.3s to get more HSC.

 

[Techfreak]

Thank you MarcusGunby!
I really understand that no one will give me a top shim stack setting. It’s OK.
I just would pleased with a stock setting from an other brand or model year in order to compare the thickness’ and diameters. Maybe so I can relate it relative to my stack (besides the different pistons or valves, linkage ratios, …). Because the new setting should be much better and not worse. Trail and error is OK but more information will make decisions easier.
I weigh 77kg in my complete MX-outfit and the spring rate is stock (4.8kg*mm^-1 or 269lb/in). I think the spring is OK (static sag).

 

[marcusgunby]

trouble is they vary a fair bit-even on just the KYBs.
A 02 Cr125 stack is something like
40.2(10)
32.1(3)
40.2
38.2
36.2
34.2
32.2
30.2
28.2
26.2
24.2
22.2
But this isnt a particually good stack-MXA seem to think it is but i dont.

Is your shock been revalved?

Ignore what i said about using 0.3s for the HSC-that is far too drastic.

 

[JTT]

Originally posted by marcusgunby
Ignore what i said about using 0.3s for the HSC-that is far too drastic.

I was kind of wondering..... ;)

 

[MACE]

Originally posted by Techfreak
My shock feels too hard over small bumps....
So my shock don’t move trough acceleration bumps and so I lost very much traction....
The rear end hops or bounce over these little bumps....
On the other hand my shock feels to soft on fast rough sections with square edge bumps....

Is Techfreak really describing excess HSC with some excess rebound causing packing on "fast rough sections with square edge bumps"???

I wonder if adding HSC and removing LSC is the wrong direction...

 

[marcusgunby]

Mace has a good point-after looking at my 02Cr125 stack i dont believe techfreak has too little HSC-far from it, and with that 24mm clamping shim im thinking that i would not like to ride that shock-the clamping shim will increase the stack stiffness alot-that combined with all that LSC shims equals a non responsive shock.

IMo that stack needs reworking a fair bit-not just a shim change here and there.

You could do with a std 97 shim stack but i dont have one.

 

[Techfreak]

Much thanks to all of you for your answers!!!
To MarcusGunby: Thanks for the compression stack setting. Now I think about it. My shock is in standard setting. I think there were no revalving. (I know the first owner.)
To MACE. I guess it’s no packing. I’ve fastened the rebound (step by step) but there were no improvement. But I’ve felt the faster rebound also on jump take offs especially if the take off has an (driven out) edge. So the shock kicks much more than before …
What do you think about that?:
I could remove some(one ore two or three) LSC shims (with the biggest diameter) in order to lighten the LSC. Or I could exchange one of the shims with the biggest diameter to a smaller one. Maybe the seventh, so the shims above can bend easier (lesser LSC). But this possibility enlarges the maximum opening angle (lesser HSC). Right or wrong?
And I could remove one or two of the smallest HSC shims in order to strengthen the HSC. (If I remove one small shim then the stack can not bend as much as before at HSC. Because the stack is stiffer and the shims stay earlier on the compression base plate. So the maximum opening angle is slightly smaller than before. Am I right? Or do they not bend so far? So maybe it’s better to use thicker shims at the begin of the stack (maybe the smallest five HSC-shims change from 0.25mm to 0.30mm)? So the maximum opening angle (at HSC) will be reduced. Right or wrong? I hope you know what I mean.

 

[marcusgunby]

Tech freak all the good settings i have only use 0.25s in the HSC and use a fair bit less LSC.Im guessing your LSC is too stiff but the lack of HSc maybe down to a problem with the shock-maybe worn oil-gas pressure im not sure but your stack doesnt need more HSC.

 

[Techfreak]

OK, I thorough thought about your words.
The oil was good. It was not old and the color was golden. (OK, that’s not a sign for a good oil. I only mean the shock sealing isn’t worn out.) And the gas pressure should was good too. The shock felt always this way.
But I rode the compression adjuster wide open (I don’t have an HSC-adjuster.). I decided for a more sensitive compression damping (traction). So I rode other lines (not through the square edge bumps) … But anytime the track was in really bad conditions. So I must ride trough these bumps and the shock was really better if I closed the compression adjuster a lot. (not more such hard impacts on the rear end)
Maybe my LSC is much to hard. So I rode the compression adjuster too wide open. And that’s way I missed HSC trough square edge bumps. The most oil flowed through the adjuster holes (without a damping effect) …
So I guess I will remove three or four of the 0.20mm-40 shims. Too much, too less??? I guess it will lighten the LSC a lot. So I can run the compression adjuster more close in order to save some HSC. Do anybody have a better idea?

 

[marcusgunby]

Sounds like a good idea-however the more i look at that stack the more im confused as to why its soo stiff in LSC and soft in HSC-the stack doesnt appear to have those characteristics.

the 0.15s are almost 2* softer than a 0.2 so effectively you have
40.2(9)
which is i suppose fairly stiff which when you have a 24mm clamp shim it will make things worse.I would get a smaller clamp shim as well as reducing LSC-no more help for you tech freak, its time to buy a shim and report back to us how it all worked out.

 

[Techfreak]

OK, I finished the work. And tomorrow I'm going to ride. I'm really exited how my suspension will work.
So much much thanks to everyone who answered me especially to MarcusGunby!!!
And I will told you how my suspension feel. At this time my home track is soft and muddy, so stayed tuned. You get an answer ...
THANKS, THANKS, THANKS!!!
(I removed three of the 40 .25mm shims. I did'nt get a 22mm shim, so I removed the 25mm shim and added a 23mm shim as clamping shim?!)

 

[Techfreak]

So the first ride is finished. And I try to tell you how my suspension felt. The track was not too bad. So I guess I need more testing time. First impressions:
My shock felt better too. My rear wheel follows the ground better than before. So I have more traction and a better feeling. I can’t say anything about HSC because the track was not so bad. (no problems over jumps or landing in flat).
At the end I would say the shock is better but not perfect. It could more softer in LSC. But I will ride more before I change the stack. In the moment maybe I would remove one or two big shims more and/or add a smaller shim (22 .10mm) at the end of the LSC stack in order to soften it?!?