Jump to content
C-P

THE KYB SSS Fork Offroad Revalve

Recommended Posts

8 minutes ago, ktmarty71 said:

I said mid valve piston

cheers

Was trying to save you an expensive mistake, glad I had it wrong. 

Carry on.. 😁

Share this post


Link to post
Share on other sites
Correct mog, I wish to add a second bleed to midvalve.

You might try an Automatic Center Punch tool. I bought a small set of drill bits (like a 4pk) for my dremel at a Home Depot.

Share this post


Link to post
Share on other sites
I said mid valve piston
cheers
It's aluminium. Put the piston in a vice with soft jaws clamped by the faces and get a new 0.9mm drill bit on a Dremel tool. Be careful.

Share this post


Link to post
Share on other sites

Thanks Numroe, that’s what I was after. Cheers

have you or anyone here played with the new style midvalve. I’ve just bought a 2019 YZ450F and want to set it up for bush/woods. I pulled the forks apart and the mid valve is not like the others I’ve had in the past ( 2015 Yz 250 2T, 2016 WR450 ). There is no float. The backing shims appear to act as the spring holding the stack on the piston.

Do I assume most of the principles remain the same but there is no float to use as a tuning tool? 

The fork works beautifully at high speed when hitting roots or embedded rock etc., but as the speeds slow down in single trail there is a little bit too much feedback through the bars. 

Thanks again for all guidance. This thread is gold. 

Share this post


Link to post
Share on other sites
9 hours ago, ktmarty71 said:

have you or anyone here played with the new style midvalve.

No, I've never worked on one.  Your description of what you want to fix, does sound like something that'd be improved if you could increase the float or "free lift" or increase the bleed on comp.  If you visualise how the oil flows at different speeds, then you should be able to use your intuition to work out what you need to change.

Now I just I found this ...

KYBfloat.jpg.97c27fd4c98b2668e28cd873ef0d5da1.jpg

  • Like 1

Share this post


Link to post
Share on other sites

Yeah I guess I’m trying to visualise that oil flow but it seemed less complicated when following the description that was put forward a number of pages ago.

It went something like mid valve moves, float blows open etc etc. The new setup to me seems like it may be more progressive as there is no “float”. Instead it employs a number of “preload” shims on the compression stack but it is stiffer than the older style with the spring.

I should point out I’ve probably only done 3 or 4 revalves on a RM and maybe half a dozen revalves on SSS forks so I’m pretty new to this. I suppose I just need to dive in and make some changes to these “preload” shims and see what happens. 

Part of the challenge of riding dirt bikes. All good fun

Share this post


Link to post
Share on other sites
4 hours ago, ktmarty71 said:

The new setup to me seems like it may be more progressive as there is no “float”. Instead it employs a number of “preload” shims on the compression stack but it is stiffer than the older style with the spring.

In both designs the face shims lift (float) off the piston very easily until the clamp shim lands on something significant.

In your newer valve design, that super soft bridging shim is a spring too. 

4 hours ago, ktmarty71 said:

Part of the challenge of riding dirt bikes. All good fun

Agreed. I love riding and find it very satisfying to try things and make the bike work better for me.

When tuning KYB or Showa mid valves, I always go with single stage shim stacks, and I tune 4 parameters to get close enough to what I want:

1. The mid comp shim stack stiffness, for the medium speed damping.
2. The maximum valve open setting for the very high speed comp damping.
3. The float gap (free lift) for the very low speed damping force and the delay before medium-high speed damping kicks in.
4. The rebound stack setting, to match the main spring and also to get the reb clicker in a position which helps me the get the amount of bleed I think I want.

I'm no guru on this stuff, but I seem to have good luck getting a good setting.

It can be quite difficult to feel what's the problem when riding. Especially if problems exist with the rear suspension or overall bike balance - and the fork is actually fine. 

3 and 4 are kind of related, since they both impact comp bleed.  Bleed is very important to get right.  As is the transition from bleed into damping.  eg. bleed stacks in base valves.

I think that 2 is the most neglected tuning parameter. It's also very sensitive to small change.

When converting from MX to offroad, I think that the common mistakes in these CC Showa-KYB fork designs are to go too soft on the base stack and/or too wide on the mid float.  Remove the base bleed stack for sure, then the whole fork can feel substantially softer with seemingly minor changes to the base stack and mid-valve parameters 1, 2 and 3.  And still hold up quite well on bigger hits.

 

Edited by numroe

Share this post


Link to post
Share on other sites

Thanks , I’ll take that all on board. 

Thanks to you I’m confident I can achieve a good all round result with only minor changes to this fork. It really does work quite well in the rough stuff even though it is a straight up MX bike. It’ll take big hits with no deflection, doesn’t dive under brakes, and landings are super smooth and progressive with plenty of unused travel. 

I feel it leaves room to soften things up a little in the square edge stuff without too many compromises.( I don’t think I necessarily want the magic carpet ride that a lot of guys talk about. I like a little bit of feedback, just not toooo much... )

Then it’ll be chapter 2. Shock absorber...

 

  • Like 1

Share this post


Link to post
Share on other sites

New to me 2015 yz250FX.  I have only had it a week.  The bike bikes suspension valving and springs are stock.  I did set the sag today but I know the bike needs a more heavy duty rear spring and to be revalved for my weight.  I can do basic mechanical work but revalving and suspension service I leave for the pro's.  I live in NW Washington.  Who is the "go to guy" or shop to dial in my suspension for my weight and riding style?  Thanks in advance!!

Share this post


Link to post
Share on other sites

I would use Les at LTR. Probably many shops in Washington that could do it but have heard good reviews from Les and have had friends happy with his work.

I would never use Moto Pro in Woodinville again. Not honest.

Share this post


Link to post
Share on other sites
No, I've never worked on one.  Your description of what you want to fix, does sound like something that'd be improved if you could increase the float or "free lift" or increase the bleed on comp.  If you visualise how the oil flows at different speeds, then you should be able to use your intuition to work out what you need to change.
Now I just I found this ...
KYBfloat.jpg.97c27fd4c98b2668e28cd873ef0d5da1.jpg
The diameter of the black shim just under the red one probably has a massive effect on initial feel since it dictates the leaf spring rate.

Share this post


Link to post
Share on other sites

So I haven't made my way through this entire thread yet, but I'm working on it. I've got a 2007 yz250 that needs shock seals and probably at least a fork service. I'm a big guy, so I should probably spring it stiffer as well, and that means I'll need to do some work on the valving. I had a look at the racetech website, and they recommend .46 fork springs and a 6.05 shock spring for a 240 lb b class rider. Do these spring rates make sense for a woods bike, and what valving setups would be good for these spring rates? I'd be looking for a fairly plush ride and I don't really do jumps, the biggest hits would probably be about a 3' drop off. I'm not a real fast rider, but like to crank it up a bit sometimes. I'm trying to decide if I should do it myself or drop it all off at a suspension shop and have them set it up for me.

Thanks,

Kristian

Edited by turbo_bird

Share this post


Link to post
Share on other sites

I recently rode a 2019 Sherco SE 300 Factory for a week offorad in the mountains in Spain. The KYB forks on that were superb, swallowed up everything with no spiking. I know the bike is a few pounds heavier, but does anyone have the spring rates/shim stacks for this bike ? Would be nice to see what's going on in there

Share this post


Link to post
Share on other sites
29 minutes ago, Wise head to fifty said:

I recently rode a 2019 Sherco SE 300 Factory for a week offorad in the mountains in Spain. The KYB forks on that were superb, swallowed up everything with no spiking. I know the bike is a few pounds heavier, but does anyone have the spring rates/shim stacks for this bike ? Would be nice to see what's going on in there

https://technicaltouchusa.com/media/wysiwyg/pdf/Complete-Data-Sheets-2019.pdf

 

scroll down a little, they're all there.

  • Helpful 2

Share this post


Link to post
Share on other sites
On 10/27/2019 at 10:43 AM, slothspeed said:

I would use Les at LTR. Probably many shops in Washington that could do it but have heard good reviews from Les and have had friends happy with his work.

I would never use Moto Pro in Woodinville again. Not honest.

Yep. :thumbsup::thumbsup:

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...