I just returned from my first serious offroad wringout ride with the 07 KLX. I wanted to wait until I had at least the right fork springs before evaluating the valving. The .44s from Moto-pro are just right for my weight.

Now I understand what some people call a compression spike in the midtravel region. I was only able to compress the forks within 2" of bottoming out (and that was with zero compression damping) - but I shouldn't have had to beat it so hard to do it. These forks definitely need to move more oil. I'd like the valving plush enough that I need my compression clickers right in the middle settings. That way each click makes a noticeable difference.

John at Motopro recommends 10W oil following his UltraMax revalve. I believe that's to emphasize our questionable rebound damping a little bit AND with the greatly increased flow, the compression can tolerate a heavier oil. Anyone know what Racetech recommends with their gold valves? I haven't decided which one I want, but I need to do something quick.

Oh, also broke off one of the humungo rear signals - no crash - just from the pounding. I knew those guys were gonna go quick. They're too big and heavy. I can see a set of flush mount LED signals in my near future.

 

RT recommends 5wt with the Gold Valve kit...and just about everything they do. You'll see a lot of suspension experts say that 7.5wt is almost always the extreme end of viscosity that you should use with a shim stack setup. A simple ported orifice design like on a KLR is different, however. The theory behind the lighter oil use is that a shim stack design becomes too limited in its ability to pass heavier oil. While the piston can easily be designed to handle the heavier oil, shim material is more uniform in its function in the industry. Now, there is some debate about this, but I see the great majority of people who seem to know what they are doing...not me...making the claim of oil around the 5wt area. Anything heavier and it indicates that something is wrong in your piston and/or shim stack...or elsewhere in the damping flow. This obviously doesn't cover suspension systems designed uniquely from the get-go to operate in a thicker oil environment.

On the rebound circuit in our KLX fork, I'm seeing this a little differently than what John's comments might indicate. I think the rebound is a tiny bit on the slow side as delivered, even on a couple of the '09 and later models I've gotten to get a feel for. And this is more of the common bias I've noticed over time from manufacturers rather than too fast a rebound. A slow rebound just packs up and yields a rough ride at a certain point. Regardless, I find the rebound on my fork to be "decent", as it's fast enough to not pack up unless there are a long line of whoops or such. Since I don't motocross with this thing, I don't encounter that as much on trails. If my compression stack was set up to run with 10wt oil, my rebound would be molasses slow and pack all the time. I could actually do with a little faster rebound. Actually I think it's hard to detect what the rebound on our fork is doing until you revalve the compression stack. The compression action stiffens up so much that the rebound is hard to discern. People are different, however.

 

I have installed the RT and I'm very happy.
But I followed my own path with respect to the oil used. I have made many tests (I opened the fork about 20 times, no exaggeration), changing settings and oils.
In the end I achieved my ideal compromise Putoline HPX5 mixing oil by 70% + 30% HPX2'5 ..
As indicated by TNC, each driver is different. I need the fork to recover very quickly to overcome small stones and steps, but also sought to avoid excessive sinking I think dangerous inaccuracies and stops going down gentle slopes.

What I would suggest is to ensure the actual viscosity of the oils. Manufacturers are not governed by a single standard and can be found with the unpleasant surprise that a SAE5 may be more dense than a 7.5 SAE another brand.
As a reference the KYB01 you install the bike is a SAE 4'3 approx. It is very good oil and it works fine.

 

jeff, your results are pretty much what I found with my setup. Your mix of 5wt and 2.5 wt was probably done for the sake of the rebound circuit, correct? I'm a little surprised at John's recommendation of 10wt in our fork. He could conceivably assemble his piston and shim stack to work with 10wt, but the non-adjustable, non-tuneable rebound stack would seem to be incredibly slow IMO.

Also, I remember Rick at Cogent Dynamics, a suspension company, actually broke into the rebound circuit of his KLX and even installed an external adjuster that comes out of the top cap if I recall. I think he said he did this because he thought the OEM rebound was too slow overall. I don't think he's going to market the rebound mod, as it might be prohibitively expensive.

 

Thanks for the help guys.

The more I think about it (usually a bad thing) the more I agree with a lighter fork oil. More rapid compression AND rebound damping.

Has anyone played around with the oil level in the forks? Seems like an increased or decreased air gap changes the compression/rebound differentially.

Worse yet, has anyone tried a set of fork subtanks on the KLX?

Think I'm leaning towards the RT goldvalves but I wish the newer edition (GV II) were available for the 07 as they are for the newer KLXs.

Does anyone sell the RTs for less than RT themselves?

 

dj, the oil level really only affects the bottomout characteristics on our fork...at least within any reasonable levels. You're basically just increasing or decreasing the air pocket in the chamber, and that affects how/when the fork bottoms. It's a very effective tuning element if you use it correctly...a little like how some of the high tech rear shock bumpers work.

I saw those air tanks from RT. There have been similar things done in the past, but I think they're a kind of bandaid deal for problems better solved by damping and spring tuning. But that's just my opinion. Plus I think they're directed more at specific track tuning for the MX crowd where you can tune because of the specific nature of a given track. Most off roaders are confronted with such a wide and varying array of trail differences, that I think you'd be constantly putzing with these things trying to find the "sweet spot".

You know, on that GVII deal, I'm pretty sure that kit will work in the earlier models too. There's no real difference in the damper rod and compression circuit design in these forks. Race Tech just probably isn't aware of it. The KLX300 and later 250's from '06 on have the same basic design components. I'm sure even some of the earlier DS 250's with USD forks are the same too. I think this is just one of those deals where Race Tech doesn't find it economically feasible to pursue for their marketing. I just used the specs for the KLX300 with the large tank for my '06 KLX, and it's been about right on the money.

 

Thanks TNC. I wasn't meaning to use the oil height as a bandaid. I fully intend to revalve the forks to improve their characteristics as much as possible. But then, perhaps the fork subtanks could be a tool to really finetune.

My last KTM was a 2002 RFS with the 43mm forks. They could be made just as good as the newer forks by adding the subtanks.... or a very cheap version of subtanks - a loop of hydraulic hose stowed behind the headlight mask and valved into the air bleed holes in the fork caps. It allowed the forks to be valved for more of a plush ride but also increased bottoming resistance sdue to the increased oil level. It offered the best of both worlds on the WP 43's. Essentially turned them into forks the same volume as the newer 48's. Guys I rode with had newer (2006's and newer) but mostly agreed they liked my 43mm setup better than their newer 48s. Some people with the 43's even valved the air bleeders directly into the hadlebar for a nice clean look. The folks with the newer 48mm forks didn't seem to benefit nearly as much from the additional air gap provided by the subtanks.

Didn't know if anyone had ever tried them on a well tuned set of KLX forks. Functional words here are WELL TUNED klx forks.

 

Just found a set of Racetech goldvalves for the KLX300 for $153 shipped online.

I talked to a racetech tech today re the version 2 vs version 1 gold valves. She said that there is essentially NO DIFFERENCE between the 2. Slight shimstack changes to the version 1 make it equivalent to the version 2. Wonder why it's $10 more?

 

From the appearance between the two pistons, I'd say some machining differences are what's in the cost. I think you'll be surprised at the OEM compression piston and shim stack compared to the GV setup. It's just holes drilled in aluminum with some standard shim washers, and it makes you wonder why Kawasaki didn't do better with their design. Fluid dynamics is not normally something you can tell much about with the naked eye, but in this case I think you'll see why the GV works so well compared to the relatively pathetic OEM setup.

 

Has anyone got a forum tutorial or a youtube link for how to install the RT gold valves? If so i would consider buying a set & doing the job myself.

My problem is after a long fight with cancer my good friend & super experienced mechanic passed away last month. Now i'm left with poorly trained Thai mechanics that never admit they don't know what they're doing, when attempting a job for the first time!!!

RIP Scottie