shock fluid weight

[kdxdazz]

FWIW, (I know that I'm reviving an old thread) I spoke to Jeff Fredette on the phone. He told me that the Race Tech spring reccomendations are too heavy. I'm a big guy (6'2"/230 lbs. without gear). Race Tech suggested a 5.77 kg/mm spring for my weight. I scored a 5.6 kg/mm spring off of ebay for $20! It's a stock take-off from any '09-'14 KLX 250S. Jeff told me that spring will likely be too stiff for me, and he reccomended a .42 kg/mm set of fork springs and 5.2 kg/mm rear spring. Just S's & giggles, I'll probably just try out the .44 kg/mm Race Tech fork springs and 5.6 kg/mm shock spring that I already bought. If its too stiff, I'll buy the lighter springs and try that! I have a feeling that it'll end up working out, as I go on a lot of longer trips, and end up with a hydration pack, 1-1.5 gallons of gas on my rear rack, as well as a medic kit and tool pack. Sometimes a couple of tubes, tire irons, and tire inflator, too.

But, for any other big KDX riders out there my little bit of research told me that the KLX 250S (and KLX 300, perhaps others) shock springs are dimensionality the same as the factory KLX spring, only a stiffer rate! Same free length, same diameter up top and smaller tapered diameter at the bottom of the shock. And, they're dirt cheap, as most of the KLX riders that change springs go to heavier springs, and put little value into the stock take-offs.

I've gone through my shock. Need to do a little research on any valving changes I may want to do, then I'll just need to fill it up with fresh shock oil and charge it to about 165 psi with nitrogen.

I've mentioned this also for quite a few years but for some reason people prefer to buy new from racetech, most Yamaha yz and wr stock springs fit too but also need the shock collars as different diameter. I'm personally using WP rear spring from the Husqvarna 350, paid 20 dollars for it
Racetech springs don't fit the kdx220sr as the SR shock is shorter and racetech springs are longer(270mm) so I will have to source another Husqvarna spring

[kdxdazz]

I used Race Tech Super Slick hydraulic oil in my KDX and DRZ shocks. This is a 5 weight oil. Both shocks are sprung for my relatively light weight, as well as the stroke shortening I did so I can touch the ground. N2 charge for KDX is factory value. N2 charge for DRZ is a little below factory value. N2 pressure is another way to soften or stiffen shock.

As a fellow lightweight guy I've spent lots of time setting up the rear shock on my kdx where it feels magic, 5 weight oil sounds super heavy given stock is a comparative zero weight when comparing Cst numbers but I don't know the Cst number of racetech oil, I'm using redline like water which is a touch lighter than stock KYB oil or at least buy my viscosity testing

The stock kdx shim stack is set up to work with a passenger and as a lightweight guy will only be optimal buy changing the low speed shim stack that's why many guys opt for gold valves

I'm also vertically challenged, I blame my dad

[billie_morini]

kdxazz,
You made me look at the Race Tech bottle. Low and behold, the:
1) actual product name is Ultra Slick Shock Fluid (Not Super Slick Hydraulic Oil)
2) viscosity is 2.5 - 5W (looks like multi-visocity)
[NOTE: I'll edit my post above per actual bottle label]

Race Tech is not revealing the centistoke values or viscosity at different temperatures. I've been told that Race Tech Ultra Slick is re-labled Motorex Shock Oil. Motorex often includes viscity measurements at different temperatures.

Do you know whether the shim stack in the shock (say that 3 times fast!) is different for SR (your 220) and R (my 220). I didn't change my shock shim stack. I changed spring, stroke length, and oil. I could not be more happy with the result.

[KDXGarage]

There's not a ton of difference between 3 and 5. It is not like 10 weight is twice as thick as 5. Just find one you like and stick to it for various valving and clicker testing.

[kdxdazz]

kdxazz,
You made me look at the Race Tech bottle. Low and behold, the:
1) actual product name is Ultra Slick Shock Fluid (Not Super Slick Hydraulic Oil)
2) viscosity is 2.5 - 5W (looks like multi-visocity)
[NOTE: I'll edit my post above per actual bottle label]

Race Tech is not revealing the centistoke values or viscosity at different temperatures. I've been told that Race Tech Ultra Slick is re-labled Motorex Shock Oil. Motorex often includes viscity measurements at different temperatures.

Do you know whether the shim stack in the shock (say that 3 times fast!) is different for SR (your 220) and R (my 220). I didn't change my shock shim stack. I changed spring, stroke length, and oil. I could not be more happy with the result.

220sr and 220r run the same shim stacks but the SR has a shorter chrome rod
In my early days of kdx ownership I listened to people on here that said just remove a couple of shims, this is wrong, the low speed shims need to be completely changed, I have it written down somewhere but from memory low speed stack is 8x0.3 and I changed to 11x0.2, I also changed the remainder high speed shims but removing large shims from the high speed stack actually makes it stiffer not softer, think leverage
In truth I didn't know what was a correct shim stack to use so I just copied an OEM wr250f shim stack which is not designed for a pillion. I figured I had nothing to lose as internet advice is completely wrong and I have spent thousands on the past with suspension tuners and they have been wrong, my bike is now super plush, I'm using a 4.2kg rear spring from a Husqvarna 350
I still have more refinement and learning to do on the SR forks as they are different to the R forks but I also have a complete showa drz250 fork conversion I have done, the forks are too short for the R model but will suit the SR version to a tee
I have xr400 forks on my other kdx neither forks are that much better than the stock kdx forks except they are adjustable for rebound which makes a big difference if the incorrect oil is used which I did on the R model forks, again bad internet advice and it was unrideable due to rebound
Learning those Cst numbers is critical and after countless hours spent viscosity testing it becomes clear how important it is, one manufacturers 10w will flow straight through where another will completely stop flowing half way
I now blend my own fork oil to suit using spindle oil from the CNC machine at work which is ISO 3, essentially like water and mix that with fork oil and oil slightly thinner than the stock KYB oil which works great with 0.32kg
Wait how did I get on to forks this is a shock oil post lol

[KDXGarage]

Maybe we can agree to disagree. I know the only thing you love more than dirt bikes is arguing. :-) More shims is more damping Less shims is less damping.

Thinner shims on the compression low stack is the way to go.

[billie_morini]

uh-oh: "I now blend my own fork oil to suit using spindle oil from the CNC machine at work which is ISO 3,..."

I wonder how the CNC machine feels about coming up short in its spindle oil supply!

[kdxdazz]

Maybe we can agree to disagree. I know the only thing you love more than dirt bikes is arguing. :-) More shims is more damping Less shims is less damping.

Thinner shims on the compression low stack is the way to go.

Half true, .some days I am patient with incorrect advice, some days not and I do hold a grudge against all the false information I was given in the early day's
Agree to disagree

[KDXGarage]

I re-read what you said and agree that removing the large ones did make it stiffer on that section.

Did you ever revalve the stock forks on rebound? There is just not much variety for improvement in those old reverse bend him pistons for compression and rebound.

[Nikwho]

Im 230-ish pounds and rebuilt my shock using Maxima 5wt fork oil. Haven't ridden it yet, but feels good rolling it around the shop so far! LOL

[KDXGarage]

You put fork oil in a shock? Is that not a big no no??

[billie_morini]

It's like he put the lime in the coconut!

[KDXGarage]

and drank it all down