KYB SSS Valving Input Please

Zman

Zman

Platinum Level Site Supporter
I put a full 2008 YZ450 Front end on my 2000 GasGas XC300. I am 51yrs old, (riding 42 yrs). 6' 4", 250lbs in street clothes.*I enjoy all kinds of riding but prefer difficult single track, trails and hills.*(probably*B-C Enduro). *
*
I changed springs to Racetech 48 with 5mm of preload.* I have tried to soften the forks about 7 times so far and below is what I have now for a tune.

The forks are still too stiff on trail trash even with the compression adjusters complete loose. They work great for big hits but they are too stiff most for most all else.
*
Midvalve
*
Nut
Washer
11mm*(x1) 0.25mm
12mm (x1) 0.11mm
14mm (x1) 0.11mm
16mm (x1) 0.11mm
18mm (x1) 0.11mm
13mm (x1) 0.11mm
20mm x0.045 (x3)* 0.11mm (Stock had 4)
Piston
20mm x 0.045" (x2)*0.11mm (Stock had 4)
17mm x 0.045" (x2) 0.11mm (Stock had 3)
11mm x 0.01" (x2) 0.25mm
17mm x 0.01" (x3) 0.3mm
17mm x 0.045" (x1) 0.11mm (moved from above)
Collar
*
Estimated Midvalve Float* 0.5mm (as I removed*two*0.11mm shims)
*
Base Valve
*
​Nut
Cup Washer 4 holes
​Spring
big silver washer with collar
​​Piston
​32mm (x9) 0.11mm
20mm (x1) 0.11mm (from*midvalve stack)
32mm (x6) 0.11mm* (stock was 18x 32mm)
30mm (x1) 0.11mm
28mm (x1) 0.11mm
26mm (x1) 0.11mm
24mm (x1) 0.11mm
22mm (x1) 0.11mm
20mm (x1) 0.11mm
18mm (x1) 0.11mm
16mm (x1) 0.11mm
20mm (x2) 1.58mm
11mm (x2) 0.25mm
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310cc 5w BelRay oil
*
*
It seems that the compression screws do not have a big impact on the dampening.* Any input would be appreciated.
 
I know sht about actual valving. I cheated and a mate revalved to KTech Club specs. Much betterer.

Opening to full open on the clickers can be more harsh as it blows through then gets stiff real quick. Best keep within several clicks of middle and find best comprise. Then revalve if that's not good enough. Any more clicks is out of range.

Sorry can't give actual valving specs as I don't have them. But they can be made good for technical.
 
Why all this lbs talk.. now I have to do conversions!

Being YZF450 forks, they'll probably have quite firm ICS rates. This adds quite a bit of firmness, especially when added with firmer preloaded springs as well.

.5mm is quite a large float, and your mid very soft.

I'd go back to around .4mm float, and a more traditional mid valve.

Address the basevalve!!

​​Piston
​32mm (x9) 0.11mm
20mm (x1) 0.11mm (from*midvalve stack) --- I don't like crossovers this small. I'd be more around 26/28mm if using.
32mm (x6) 0.11mm* (stock was 18x 32mm)
30mm (x1) 0.11mm
28mm (x1) 0.11mm
26mm (x1) 0.11mm
24mm (x1) 0.11mm
22mm (x1) 0.11mm
20mm (x1) 0.11mm
18mm (x1) 0.11mm
16mm (x1) 0.11mm ----> this is your main issue.
----------add clamp 14mm x.3mm
20mm (x2) 1.58mm
11mm (x2) 0.25mm

Simply changing the clamp to a 14/13mm shim x .3mm you'll soften the whole stack up. You may wish to pull a couple more face shims as well.

Also, considering that you've upped spring rates, you may wish to add a bit more rebound control as well.
 
Note, just checked spring rates, and they should be fine. Even if you have the firmer ICS springs.

So I'd add another face shim back to both sides of the mid valve. That will close your float to approx .39mm.

Then soften the basevalve to something like the following.

32 (6)
26
32 (6)
30
28
..
14.3 (or 13)

Then test.
 
Thank you both.

Jakobi -So to make sure I understand you correctly I should modify it like this?

Midvalve
*
Nut
Washer
11mm*(x1) 0.25mm
12mm (x1) 0.11mm
14mm (x1) 0.11mm
16mm (x1) 0.11mm
18mm (x1) 0.11mm
13mm (x1) 0.11mm
20mm x0.045 (x4)* 0.11mm (Stock had 4)
Piston
20mm x 0.045" (x3)*0.11mm (Stock had 4)
17mm x 0.045" (x2) 0.11mm (Stock had 3)
11mm x 0.01" (x2) 0.25mm
17mm x 0.01" (x3) 0.3mm
17mm x 0.045" (x2) 0.11mm (moved from above)
Collar
*

*
Base Valve
*
​Nut
Cup Washer 4 holes
​Spring
big silver washer with collar
​​Piston
​32mm (x6) 0.11mm
26mm or 28mm (x1) 0.11mm (I will see if I can find one in a set of WP43s)
32mm (x6) 0.11mm* (stock was 18x 32mm)
30mm (x1) 0.11mm
28mm (x1) 0.11mm
26mm (x1) 0.11mm
24mm (x1) 0.11mm
22mm (x1) 0.11mm
20mm (x1) 0.11mm
18mm (x1) 0.11mm
16mm (x1) 0.11mm
14mm or 13mm (x1) 0.3mm (I will see if I can find one in a set of WP43s)
Do I remove both 20mm and the 11mm or do I keep the 11mm?

Thank you for the help!
 
The shims below the main stack are referred to as the bleed stack. By running as below they don't block any ports off, which isn't needed for off road so I'd keep them as is:

20mm (x2) 1.58mm
11mm (x2) 0.25mm

Have a look at the assembly and where they sit and you'll see what I mean.

Everything above looks pretty good.
 
Ok so my Base Valve will look like this?
*
​Nut
Cup Washer 4 holes
​Spring
big silver washer with collar
​​Piston
​32mm (x6) 0.11mm
26mm or 28mm (x1) 0.11mm (I will see if I can find one in a set of WP43s)
32mm (x6) 0.11mm* (stock was 18x 32mm)
30mm (x1) 0.11mm
28mm (x1) 0.11mm
26mm (x1) 0.11mm
24mm (x1) 0.11mm
22mm (x1) 0.11mm
20mm (x1) 0.11mm
18mm (x1) 0.11mm
16mm (x1) 0.11mm
14mm or 13mm (x1) 0.3mm
20mm (x2) 1.58mm
11mm (x2) 0.25mm

I see your point how adding the 13/14mm will soften the whole stack.

So if I understand correctly, my present stack does not have a bleed shim because the 32mm shims are placed directly against the piston? A bleed shim in this stack might be an 11mm placed between the piston and the first 32mm of the main stack?

This may be a silly question but if I can not get a single 13 or 14mm x 0.3mm thick can I build it from multiple thinner shims (adding up to 0.3mm) and get the same results?
 
I found that I have a pair of 21mm and a 24mm. Will they work in place of the 26 or 28 or will that make it too soft?

I also have a pair of 12mm, 14mm and 16mm 0.11mm thick. Can I stack these to get close to the 13/14mm 0.3mm or would it be better if I just order the correct ones?

If I am ordering shims should I get the metal free pistons too or don't replace them until they break?
 
You can try the 14x.11mm clamp. Usually just aim for more to allow more room for the shims above to flex over the clamp if required.

You can try the 24mm crossover if you like as well, or simply leave the crossover right out and run a straight stack.

With the KYB they have an option for a bleed stack. This essentially bypasses the clicker. By running your 11.25 (2) and the spacer at the bottom of your compression stack you are leaving the small ports open, and bypassing this.

This is different to what is referred to as a bleed shim, and that is exactly what you have said above. It sits between the face shim and piston face to allow the ports to be partially open at all times, allowing bleed.

The free pistons, if they aren't broken and look in good condition I would simply drill them to avoid the pressure build up that breaks them. Otherwise if you want to drop some coin you can get the metal ones.
 
Thank you Sir!

So I could actually run the 12mm under the 14mm to make it a bit thicker and allow for more room for the compression stack to move.

For my situation is there a benefit to leaving the bleed stack in place or should I invert it as shown below?

Am I correct that the 24mm in the middle of the twelve 32mm will soften the initial part of the stroke when compared to the consecutive stack of 32mm?

Nut
Cup Washer 4 holes
​Spring
big silver washer with collar
​​Piston
​32mm (x6) 0.11mm
24mm (x1) 0.11mm
32mm (x6) 0.11mm
30mm (x1) 0.11mm
28mm (x1) 0.11mm
26mm (x1) 0.11mm
24mm (x1) 0.11mm
22mm (x1) 0.11mm
20mm (x1) 0.11mm
18mm (x1) 0.11mm
16mm (x1) 0.11mm
14mm (x1) 0.11mm
12mm (x1) 0.11mm
11mm (x2) 0.25mm
20mm (x2) 1.58mm
 
Instead of thinking about parts of the stroke, think about shaft speeds and fluid displacement.

With the crossover, it means that for slower shaft speeds that only displace a certain amount of fluid over a certain time, it'll allow the first 6 shims to flex easier, offering less resistance. For faster shaft speeds and higher displacement those shims will flex to contact the other 32's and continue to build damping.

Running the 12 under the 14 changes the clamp/pivot and will soften the whole stack further again..

I'd try this.

​​Piston
​32mm (x6) 0.11mm
24mm (x1) 0.11mm
32mm (x6) 0.11mm
30mm (x1) 0.11mm
28mm (x1) 0.11mm
26mm (x1) 0.11mm
24mm (x1) 0.11mm
22mm (x1) 0.11mm
20mm (x1) 0.11mm
18mm (x1) 0.11mm
16mm (x1) 0.11mm
14mm (x1) 0.11mm
20mm (x2) 1.58mm
12mm (x1) 0.11mm --can remove if you like, or leave in place. Won't influence anything.
11mm (x2) 0.25mm

If it still feels to firm just order a 13.3 from somewhere as your new clamp and it'll soften things further. Changing the clamp is a pretty noticeable/significant change.
 
MX-Tech is 1.5 hours away from me so I ordered the 26mm and 14mm shims to save time.
 
Jakobi - I was able to swap out the shims last night and I went for a quick ride today. I think your suggestions that took care of my problem. The forks soak up the small stuff much better and they fell very progressive. I need to go out for a real ride to get them dialed in. I will try to do that next weekend. Thank you again Sir!
 
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