Re-valving the stock KYBs
 

I am wondering how much of a difference it will make to revalge the kyb suspension on a 2018 300. Everyone talks about how great the KYBs are right out of the box so would getting a professional re valve make much of an improvement? I am a fast B racer in XC races but I also like to do a lot of single track/hard enduro riding...I haven?t raced any of these types of events yet but want to in the future. I have an EVO and racetech guy near me who are both very reputable and I can get the EVO at a pretty big discount. Would it be worth it at my level and type of riding?

Have you sprung the bike for your weight and set the sag?

Yes I have

It will make as big a difference as the tuner tunes!!

Given that you have already sprung the bike to suit your weight I'll assume you've also put some seat time in.

What does it do that you don't like? Have you adjusted any of the variables at your disposal? ride height, preload, clickers, etc. Did you see any improvement?

Have you owned another bike which you felt handled better? If so, how?

The point I'm making is that if you go to a tuner and ask for a revalve, then my guess is as good as yours if it will be better or worse. If you go to a tuner with some information they could probably improve certain behaviours.

In saying that, I've revalved all my own suspension over the years and been a bit fussy in that process as well. Not too many people have felt the need to revalve these (myself included) which to me indicates they are pretty good stock.. not to say they couldn't be improved a bit more.

Honestly the stock suspension feels great for the most part and the bike handles well. It still feels a bit soft when blitzing whoops in XC races and a bit stiff on some of the more technical slow stuff. I am trying to find a happy
Medium for both styles of riding I do which I think I am pretty close, but was wondering if getting an after market revalve would improve this happy medium for both styles of riding.

I have never had suspension work done on any bike besides new springs

I’m really surprised that you say it feels soft. Nearly everyone that rides these bikes has them softened up. At 260lbs and a B rider myself, I feel the stock suspension is nearly spot on. I did however got to a lighter ICS spring which softens up the initial stroke but maintains the firm midstroke and excellent bottoming resistance. I’m wondering, what weight are you and what springs did you go with?


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I think most tuners would easily be able to help you with one issue or the other.. but you'll get stuck trying to find any suspension that works across such a big scope. There'll always be some compromise. Think about the difference in force and suspension component velocity between rolling over rocks at walking pace and slamming into the face of a whoop at speed.

What's your current setup? Spring rates, sag figures, fork height in the tubes. Clicker settings etc.

Which softer ics springs did you use? I'm very happy with the suspension overall but it could soak up the rocks and roots a bit better.

Do you have info on what the stock ICS rates are? What did you end up moving to? In the previous set I had fitted to the 13 model I used the stock 22Nm springs..

Stock is 1.8 I dropped all the way to 1.0 and they worked well but I was experiencing what I believe is cavitation. I was having extreme air pressure build up during rides. Went to a 1.4 rate and the cavitation issues went away and the initial stroke is still pretty good.

My friends that are much lighter riders than me all have the 1.0 ICS springs and have no issues. I’m 260lbs


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What would be the difference(or benefit) between softening up the ICS spring or using less oil?

I've read of a couple of guys who have tried lowering the oil level with good result re: the slower stuff.

Jeff

What's the stock oil volume? Anyone know?

The whole point of the ICS is to keep the oil in the inner chamber pressurised to prevent cavitiation (bubbles forming that reduce damping efficiency). The KYBs don't run a preloaded ICS so they generally allow a little cavitation at the initial stroke anyway, but the further into the stroke you go the further the pressure increases.. however the increase is linear!

The oil volume acts as lubrication for the bushings and seals. The remaining volume of the fork (filled with air) then acts as a spring.. however the curve is not linear.

Usually oil volume has much less effect on initial stroke, and more to do with ramping up and bottoming resistance.

BUT! The whole system works together.. valving, springs, air gaps, etc.

Thanks, makes sense!

Jeff

Heres a visual..

https://www.youtube.com/watch?v=GBcRBOikb8c

I found a set of mx tech element 7 bladders and I now have the best set of KYB's I have ever ridden. If you can find them make sure to buy them.

I believe that I measured 350cc of oil in the outer chamber when I did my first oil change on my '18. I am running 320cc now and still have excellent bottoming resistance. I feel like the lower oil height made the forks a little plusher on the trail trash and smaller hits. The great thing about starting low with the oil height is that you can add oil through the bleeders in 5cc increments to dial it in.

I am 190 lbs, 200-205 geared up to race. I went to a 5.8 newton shock spring and went up either 1 or 2 increments stiffer in the front. They are Q springs that I got from JDP in Ohio and talked to him and these are what he suggested. Race and static sag are set perfectly with the shock spring rate he gave me. Don?t get me wrong the suspension on this bike is great I just find myself getting tossed around on whoops sometimes, maybe it is a fatigue and form issue on my part. Sometimes instead of the bike working to carry me through the whoops it will start going too far down in the stroke and get me out of rhythm, but I?m afraid if I go too far in adjustments it will be too harsh in the slow technical sections. Was just wondering if a revalve would actually show any improvement in both of these areas without too many adjustments. Maybe it?s just my issue and I should work on my skills some more.
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While we?re on the subject I have the motion pro air bleeders on my forks and they seem to get filled with oil and not bleed the air properly until I let the bike sit for a few days. I wonder if this is having a big effect on the feel of the forks?

I have never used the quick bleeders, but I have noticed that the forks can build up pressure and it does decrease performance.

315ml is what I used to run on my previous setup. I wasn't banging woops though either... nor am I what you'd call fast.

What I would suggest.. is that you contact a tuner and see if they are willing to work with you. I don't personally see any value in them just slamming their favourite stacks into your forks and hoping you love it.

It could be as simple as your rebound being too slow.. it could be the high speed compression needs to be firmed up. Given your weight and your spring rates I don't think it's a lack of spring.. BUT a decent tuner should be able to put you through a set of whoops and see what is happening, make some changes, etc. They really need to know the specifics of what is happening to be able to make informed decisions on how to resolve it.

I used to run 320ml in the TM?s Kybs with slightly stiffer springs, 350 works well for me now with springs that are a rate too soft.

Hate to start a new thread for this question -

If you remove the KYB fork Base/Compression Valve (say, to play with shims & valving) do you need to bleed the cartridge when you put it back?

Or can you just remove handlebars, unscrew Compression Valve, and just screw it back in when done making adjustments?

Jeff

Similarly, when I remove the cartridge to replace fork springs, does it need to be bled before replacing?

The base/compression valve is inside the cartridge. Hence, if you open the cartridge, as you say, "to play with shims and valving", you have to bleed the cartringe after filling it with oil.
There should be no need to bleed it if you didn't open it, which you won't do if you just replace the springs.

Thanks Anders, I appreciate that!