DIY tuning the Sachs shock

[Kyle Tarry]

That one actually doesn't look too terrible! I would think that bike would feel decent, although probably pretty soft on bigger hits.

With 1.4mm of float, that midvalve isn't doing that much. If you think about the flow area, with that much lift the area around the base of the shim is about the same as the port area. You'll still get some damping out of it, but it's probably about the same damping as you'd get with no shims on there at all (except that rebound would be awful in that case). Which, I might add, I think is actually significant; the midvalve in a fork can move pretty fast, and has to pass a lot of fluid, so even without shims blocking the path you still get nontrivial damping forces out of it.

The reality is, enduro midvalves are quite a bit like orifice damping. They snap through the float pretty easy, bend back a bit, and then they can't open any more, and you get real progressive damping out of them.

Try something like this on the mid:

23.1 (3X)
20.1
18.1
16.1
14.1
12.1
10.?
Backer (18-20mm dia)
Float 0.7mm ish

 

[Picklito]

It was actually very harsh on chop. He's out testing now with this MV:
22
22
18
14
12
11
1.0mm float

 

[Kyle Tarry]

Which BV pistons did that bike have?

If it was my bike, I would have drilled them out as far as I could, pulled a face shim or two from before the crossover, maybe a smaller clamp, and gone to a MV stack sort of like you posted but with 0.7-0.8 of float.

Where are you at now on the base?

I also wonder how much of the problem with these forks is on the rebound. I've messed with mine a little bit, but there may be room for improvement.

 

[Kyle Tarry]

Random ReStackor note:

I've been doing some work with a friend's DR650 shock, and in the process I got to talking with a guy who has dyno tested one of them. ReStackor's predicted damping force and the dyno measured damping forces are within about 10% across the whole speed range he dynoed. On rebound they are really close (about 5%), on compression they're a bit further off (10-15%) because I am not calculating any input from the compression adjuster.

In any case, it's encouraging to see that the numbers are actually fairly close to reality, that makes me a bit more comfortable using it as a tool.

 

[gots_a_sol]

Any new input? I need to change the oil in my 165's shock and am thinking about playing around in it a bit (I've messed with forks, but this will be the first attempt at a shock). As far as I know it is stock stacks in there.

 

[gots_a_sol]

Here is what my shock had in it. I'm pretty sure somebody has messed with this before now.


Rebound

38.25
38.3
38.25
36.3
34.24
34.3
32.25
30.3
28.25
26.3
24.25
22.3
24

Comp

44.2
44.2
44.2
44.2
44.2
28.1
44.2
42.2
40.2
38.15
36.2
34.15
32.2
30.2
38.25
26.2
24.25
22.3

And while I was messing with suspension, I dug into a set of KYB SSS forks I had that are off a brand new '13 TC250. My TXC 250 has these same forks that were revalved previously and they work pretty well. As soon as I find the paper I wrote those stacks on I'll post them.


Stock 2013 TC250 KYB SSS forks:

Base
32.1 (18)
30.1
28.1
26.1
24.1
22.1
20.1
18.1
16.1
15.1
14.25
18.3
18.3
18.3
20 x 1.6
11.25
11.25
22.1
22.1
22.1

Mid
Rebound

20.1
20.1
20.1
20.1
13.1
18.1
16.1
14.1
12.1
10.25
16 x 1.6

Comp

20.1
20.1
20.1
20.1
17.1
17.1
17.1
11.25
11.25
17.3
17.3
17.3

No float at all.

*edit* Modded KYB forks. Looks like the mid rebound is the same, just changes to the base and mid comp.

Base

32.1 (10)
30.1
28.1
26.1
24.1
22.1
20.1
18.1
16.1
14.3
11.25
20 x 1.6
10.2
14.1
16.1
18.1
20.1
22.1

Mid
Rebound
20.1
20.1
20.1
20.1
13.1
18.1
16.1
14.1
12.1
20.25
16 x 1.6

Comp
20.1
20.1
20.1
18.1
16.1
14.1
10.25
10.25
17.3
17.3

Float = 0.6

 

[flyingbob]

Here's what I found in a 2002 WR250 Sachs shock today.
50mm piston with no bleed holes. Copper/teflon coated seal, no o-ring provision.
Converted to a bladder reservoir.
Rebound
.70-19
.25-22
.25-24
.25-26
.25-28
.25-30
.25-32
.25-34
.25-36
.25-38
.20-38 x 7
------------
Compression
.15-44 x 9
.20-44 x 4
.20-42
.20-40
.20-38
.20-34
.20-32
.20-30
.20-25
.30-23
.30-21
.30-23
2.50-33.50

High-speed comp was full out
Low-speed comp was 9 out
Rebound was 15 out

Bike was in parts so I haven't ridden it.
I had bought and sold this bike about 5 years ago and don't remember how it felt then.
Oil was dark, not opaque though.

Opinions?
Seems a lot different than anything else I've read...

 

[Mantti]

I've done a couple of the Marz 45s, and I really like the way they turned out on my 610. If you want to bounce some ideas around, I'd be glad to. One thing I have done is convert the stock checked mid to a regular active mid with about 0.7mm of float. The bike is amazing, it eats rocks and yet I can pound sand whoops all day and never bottom. I just made a slight change to mine to firm up the base a little bit because I was running the comp adjuster pretty far in, but I think (hope) it will still work really well. On some level, I wish I could get the KYBs on my WR to feel that good...

As you seem to have working setup for TE 610, what are you running on shock? My -06 was previously in SM so it has pretty much different setup and feels quite harsh on small roots and rocks.

 

[Picklito]

Has anyone played with the shim stack inside the High Speed Compression adjuster?

 

[rgmr250]

Hey guys, just wanted to check in and make sure I am going about this right before I screw something up...

I am trying to unscrew the top of the cartridge in my WR's KYB OC forks, so I can get to the midvalve. See picture below:

Since KYB put the bottom-out dealie (left side) on with a crimp, there's no getting that off (thanks, KYB!). Am I correct in stating that the "cap" (the shiny billet machined part on the top/left of the cartridge tube) will unscrew from the rest of the tube?

If so, I am going to make a clamp to hold the tube, and another special tool to engage with the four "slots" on the spring seat with a hex or some wrench flats on it.

I made a quick attempt at it in the garage by just sticking a 1/4 inch rod through the holes at the bottom of the cartridge, and grabbing the "cap" with pliers; apparently that thing is on there TIGHT, I bent the rod and nothing moved on the cap.

No evidence of peening on these parts, so that's good. I suspect there is loctite? I applied a little bit of heat but I don't want to damage anything in the tube...

I just wanted to follow up on this. I have a 2010 TE250. I bought the bike with the forks already lowered, but wanted to go back to stock height, so there was a spacer on the rod inside the cartridge, so I had to take the cap off as well. I'm glad I found this, a little heat with a propane torch and it uncrewed fairly easily. Interesting that I was unable to find pictures/videos of any other Kayaba/KYB forks that are just like this.

 

[roj00]

I am trying to improve my fork set up, I am new to playing around with valving so any help would be greatly appreciated.

I am 67kg with no gear on and the bike has done 24 hours so everything is in good shape internally.

I don't like the current set up is it is a little harsh with small bumps.
I was thinking of removing two of the 24mm shims, Dose anyone know if I am on the right track?

I am running 4.0 springs in the forks and a 5.2 in the shock, one rate softer than stock, should I be considering a shim change for the softer spring rate as well?

I am keen to do whatever possible to make the forks and shock work the best they can.

Currently my comp valve stack is stock, see below.

24 .1
11 .3
18 1
18 1
18 .5
11 .25
13 .15
16 .15
18 .15
20 .15
22 .15
12 .1
24 .1
24 .1
24 .1
24 .1
24 .1
24 .1