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Guru's...here's my shock stack, I would like to reduce high speed comp pleeez

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Hey everyone,

Been a while, hope everyone's getting some good fall riding in right now. I have recently moved to Santa Fe, NM and am giddy with excitement over how much riding potential is here. Quite a contrast from back in the Washington DC suburban hell-hole I will now refer to as Mordor from now on....

Anyways, went out for some high desert riding recently and fell in love with my KX125 all over again. The faster, flowy, loose and sandy trails and just so much better suited to this bike than the slow and technical rocks back east. I do have one issue I noticed pretty good and was hoping you all could help with. I'm at faster speeds now and the climbs being loose, I have to attack at a higher speed being on a 125. The rear is kicking pretty hard, for example trying a climb yesterday that has a fast run-up in 3rd,then about 100 feet up a few steps about 1 foot high. The bike would literally swap sideways and spit me off everytime. And on other climbs it's just harsh, but not that extreme, so would changing the high speed stack help this? I like the handling of the low speed right now a lot and would like to keep it the same if possible.

Here's the final setup as of right now on my KX125 2003:

KYB shock in a 46mm body I believe, and it has LSC and rebound adjustments only. Both ends of the suspension were stock before I got into it.

COMP.

40 x 0.20 qty. 7 (stock has 11)

34 x 0.10

30 x 0.10

(40 x 0.10 removed from here)

38 x 0.30

36 x 0.25

34 x 0.25

32 x 0.25 (All of these .25's were 0.30 stock)

30 x 0.25

28 x 0.25

24 x 0.20

19 x 0.75 (stock uses a 22 x 0.20 clamp, I took a spacer from elsewhere since the shims ordered were incorrect)

Baseplate

REBOUND - still in stock form

36 x 0.25 Qty. 5

28 x 0.15

36 x 0.35

34 x 0.35

32

30

28

26

24

22

Baseplate

Clickers are at the halfway point now, and the LSC comp ports drilled to 3.1mm. 180psi in the bladder. Sag is at 105 I believe. Thanks!

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As general rule swapping is to much high speed hitting in the backside is too little

If you want to soften off the high speed change the 38x.3 to .25 the change all the .25 to .20 but I would add 26x.2 after the 28 and 22x.2, 20x.2 after the 24 then clamp it

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If those are .35's in your rebound taper that might be part of your problem too.

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Yz295, what do you mean by "hitting"? Harshness? The sensation I get when hitting a large square edge is that is sends the rear up quickly and my feet try to lift off the pegs, but it doesn't feel like it's on the rebound. I have tried turning the rebound in and out, too much in feels like I'm packing and too fast rebound was smoother but sometimes the rear lifts up and feels like it's gonna endo.

GHILL28, would this change affect HSR, but keep LSR the same? I may just order shims for both stacks and try em. Sounds like I need to soften high speed both directions, correct?

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If you are hitting things faster than before could it be that your bottoming? Running out of travel causing the chassis to kick up?

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If you are hitting things faster than before could it be that your bottoming? Running out of travel causing the chassis to kick up?

I don't think I'm bottoming, but not 100% sure. I was always under the impression that my suspension was pretty stiff. This weekend I was landing a 6 foot drop to flat ground pretty consistently and it was not harsh one bit.

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You can revalve the compression adjuster too for a little more blow-off.  It uses a simple shim stack to bypass the clicker on high speed hits.  That may help somewhat.

 

If you aren't bottoming into the fender yet you might as well go further on softening the HS stack.  Pull some shims.  The 38 x .3 could go.

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Awesome. Sounds like the easiest thing to start with is the removal of the 38x0.30 shim. That was actually the intention for my first revalve, but the shim supplier sent the wrong one so I left it.

As for the comp adjuster, I'll maybe have to tear into again. I removed it to drill out the ports, but can't rememebr the stack, although I think it only consisted of about 4 shims of a very small size. All I know is that when back in Virginia I would back out the LSC fully to deal with the huge rocks, but hated the way the bike would wallow on moto-style turns. It had a very unbalanced feel from front to rear. Chopper-ish sometimes.

Thanks for everyone's comments, I'll post up results after the change

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The comp clicker is fairly inefficient when it comes to dealing with stuff like rocks or square edges.  It has some effect but it has a greater effect on other things that you didn't want to change.

 

I've been doing well with eight face shims on my 03 KX if I remember correctly.  I know I pulled a few out from stock and stiffened the tapered portion of the stack.  The stock shock seems firm until you really come down on it, then it seems to bottom fairly easily.  The softer low speed works great for me but I think we do different kinds of riding.

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Ah I see. Most of my riding is going to be on high desert singletrack, some of it might be a little rocky but I have a feeling it'll still be smoother than what I'm used to from back home. We have an MX track right here in Santa Fe that I'm sure I'll be riding on soon but I'm a total novice when it comes to MX. Even on trails I'm a fast C rider at best.

The reason why I want to keep the LSC mostly unchanged is because it took me forever to get it dialed for my riding style. I'm not one to keep it on the pipe in turns and usually pull one gear higher and use the clutch for a little wheelspin. With the LSC nice and soft I found that the bike would push in turns unless I was really roosting it. But this style of riding tires me out faster and I make more mistakes in the long run, so I started setting the bike up for sharp turn-in and it just felt like the higher stance in back helped a lot.

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This worked well for me on an old 2005 YZ250 KYB shock that had a 16mm shaft:

 

C

40.2 (11)
34.1
30.1
38.2
36.2
34.2
32.2
30.2
28.2
24.25
22.25
21.3(2)
plate
 
 
R
36.2 (6)
28.1
36.3
34.3
32.3 
30.3
28.3
26.3 (2)
24.3 (2)
22.25
Plate

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Yz295, what do you mean by "hitting"? Harshness? The sensation I get when hitting a large square edge is that is sends the rear up quickly and my feet try to lift off the pegs, but it doesn't feel like it's on the rebound. I have tried turning the rebound in and out, too much in feels like I'm packing and too fast rebound was smoother but sometimes the rear lifts up and feels like it's gonna endo.

GHILL28, would this change affect HSR, but keep LSR the same? I may just order shims for both stacks and try em. Sounds like I need to soften high speed both directions, correct?

When you are running into your obsticals (hitting them) if the seat/guard is hitting you in the bum your high speed shock setting is too soft

If when your hitting obsticals the rear end skips sideways it is too hard

To set the rebound

Stand at the end of the seat near the axle,

push down on the seat / guard with both hands fast and hard

The bike should return to the top the settle back down

If it comes up and bounces slow it down

If it comes up and sits ( doesn't settle back down) quicken it up

Then with one foot on a stand or crate the other on a peg push down on the peg and bars and let the bike come back up

Adjust the fork rebound so the fork raises the same as the shock

Note: this setting is generally too fast for most people and feels loose, simply because they are used to slow and low settings, but it will give you faster lap times

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I don't believe the seat ever hits my ass on bumps, but it sure does deflect sideways. Like my front end did before I revalved it, almost like a sharp hit where I swear I can feel the tire bottoming on the rim sometimes. I guess we can all agree that I need to soften the HSC, possibly HSR so I'll be ordering shims pretty soon.

I know(from reading and from tuning a few friend's bikes) that most people feel faster on an over damped set up, and I always try to train my brain to feel confident on a loose bike. Where i have it now is worlds better than the stock setup when I bought it, and I'm pretty sure that if I get the high speeds on the shock dialed without messing up the low speed I'll be good and done....for a while.

Hell, if I happen to get so fast that I need to revalve both ends again I won't complain!

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I don't believe the seat ever hits my ass on bumps, but it sure does deflect sideways. Like my front end did before I revalved it, almost like a sharp hit where I swear I can feel the tire bottoming on the rim sometimes. I guess we can all agree that I need to soften the HSC, possibly HSR so I'll be ordering shims pretty soon.

I know(from reading and from tuning a few friend's bikes) that most people feel faster on an over damped set up, and I always try to train my brain to feel confident on a loose bike. Where i have it now is worlds better than the stock setup when I bought it, and I'm pretty sure that if I get the high speeds on the shock dialed without messing up the low speed I'll be good and done....for a while.

Hell, if I happen to get so fast that I need to revalve both ends again I won't complain!

Then the high speed is to much and your right most people "feel" faster over dampened but your fastest times will come from

The most compression damping you and the track can handle

And

The least rebound damping you and the track will allow

But to most this "feels" out of control loose flighty but it's because they are traveling faster and their brain hasn't caught up

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Cesper - Let me ask you this... is the rear wheel swapping side to side but not bottoming? If so it's deflecting really because the LS compression is too stiff... If that's the case soften the low speed (or first part) of the compression stack and you need to open it up so oil can flow and the bike can follow the ground. You have qty 7 40x.20 shims right against the face of the piston. Try this below...

 

You'll know quickly if you're going in the right direction with this. The rear should track to the ground better if indeed the LS has been too stiff. If you're light (under 155 lbs you may want to put this bleed shim right under the first shim on the face. Also, make big changes to stacks till you know which direction is correct. 

 

 

COMP.
40 x 0.20 qty. 2 

20 x 0.20 qty. 1    - this is what I call a bleed shim to get the bike more compliant on the chop... If you're light move it up to just under 1 face shim. 

40 x 0.20 qty. 4 
34 x 0.10
30 x 0.10
(40 x 0.10 removed from here)
38 x 0.30
36 x 0.25
34 x 0.25
32 x 0.25 (All of these .25's were 0.30 stock)
30 x 0.25
28 x 0.25
24 x 0.20
22x .20 clamp - put this back if you have it and pull the 19 x 0.75 
Baseplate

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Racing suspension products makes a drop in hsc adjuster, which gives you the adjustment that stocker lacks.

my friend has used it in his kx shock, and he was very happy with the results. the mod will bring some different comp stacks into play as well.

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Racing suspension products makes a drop in hsc adjuster, which gives you the adjustment that stocker lacks.

my friend has used it in his kx shock, and he was very happy with the results. the mod will bring some different comp stacks into play as well.

Thanks, I'll keep it in mind. I usually order my shims from them, but the adjuster might have to wait a few months. A little experiment today, backed all adjusters out fully EXCEPT the shock LSC, bike seemed to handle best so far. Feels kinda loose, but I was for sure cornering harder and more predictable than last ride. As for the steps up on the climbs, well I think I felt a slight improvement and my first guess is that the rear was trying to pack up and now it's staying high enough and tracking on multiple hits. At least that's what it felt like. Just to get rid of the floaty-ness out back on the faster stuff I turned the rear rebound back in 4 clicks and it was a good balance.

PT564- I can try less low speed, but thnk it may be the opposite way I need to go, for rear LSC at least. Here's why-

My trails are fast, flowy single track very narrow in the high desert and mostly loose/sandy and sometime beach sandy. It's pretty common for the straights to have these large whoops, imagine riding in and out of several giant wheelbarrows, sometime 10 back to back. As of now, after hitting about 3, the force from my weight gets to be too much and I get close to bottoming, then pogoing off line and losing all my speed....if I manage to stay on the pegs(yes I'm standing, on balls of feet). These would be controlled by low speed comp, yes?

I'll still give it a shot, but as stated before in addition I've played with the LSC both directions and did not like the softer setting. Too wallowy in corners, I'd imagine here in the sand it'll be even worse, but worth a try nonetheless.

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Understood. I was very surprised at what I found when I softened the LSC... the bike just tracked much better over all that small stuff. Even at speed! I think most people think something "packing" it's a LSC issue... that can be a rebound issue. Are you bottoming on these hits your talking about? If you're not blowing through the travel on the first two hits softer LSC could help... You have to go there to know. Don't go in little steps. Make big changes on the stack till it tells you the correct direction. I was taught this by a guy that ran Fox racing shox's for many a year.... Go big to find the direction. 

 

I've done a lot of this stuff and my mind set is changing. I'm finding you want to go to the point where something is too soft and then stiffen it up from there. Soft is good! It means things are getting absorbed. Most start too stiff and stay there. Go softer to the point where you feel bottoming then work up stiffer from there...

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So I rode today and backed everything out again, even LSC like you recommended on the shock. It was better, and didn't allow the rear to wallow as much as I thought it would. I think the fact that my technique for cornering is improving also helps combat that. Getting on the gas earlier in a corner seems to help reduce the squat.

I also tried going full stiff on the fork compression today, and that was an improvement most of the time, too. Last few rides I've noticed that I felt bottoming on the sand whoops when I didn't time them right(basically overshooting one and hitting the face of the next one), so I went full in on the fork comp and it not only helped keep the fork from diving hard, but it also allowed me to stay on top of them a little too. So now I just have to work on that technique. My trails have tons of them, so it's a skill I need to improve to enjoy the rides more. Lots of whoops on the straights and lots of braking bumps.

So seeing that the shock feels better with everything out, I guess the logical step is to soften both stacks. Then I'll work on the fork.

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