shock fluid weight

[ridinredneck]

2002 kdx 200. rider is 215 lbs. changing shock fluid and spring. thinking of using 3wt fluid. is that good or would you suggest a different weight of fluid?

[bufftester]

With the stock shock that will give you less rebound compression (your shock returns from compressed to uncompressed faster. Short of changing the valve shims internally it's really the only rebound adjustment you can do with the stocker. Thought stock was 5wt, could be wrong. I am running 7wt in my hybrid, but have the benefit of full rebound and compression damping adjusters (KX shock). More important is to get the spring rate correct for your weight. And of course if you haven't done it the front needs to be resprung for your weight. Stock the front is good for those lightweight 160 pound guys, not us substantial mass guys

[KDXGarage]

Check out the peter verdonne chart for more info, but I have read from several tuners that a great three is about the same as stock 5.

I liked Silkolene RSF Pro 3 back a few years ago.

[Gotanubike]

3wt is good for most standard shocks and 7wt is recommended for shocks with high-flow valving modifications. Kawasaki says 5wt in my(e series) manual but you'd probably be ok using a 3wt is that's all you can find.

I could not find 5wt so I went with 7wt in mine and now sorta wishing I got the 3wt but we'll see how it works, I'm just finishing up my shock now

[ridinredneck]

i have read that the stock shock is a little stiff. thats why i was thinking 3wt.

[KDXGarage]

Revalve it to your liking.

[ridinredneck]

may revalve when funds permit. but for now its just spring and fluid

[KDXGarage]

If the spring has been far off and the oil is real old, you will be in for a treat!

If you get around to the revalve, try to use thinner shims than the .3's that are on the compression side. It will help.

[ridinredneck]

well the stock spring is a 5.0 i believe. race tech suggests a 5.75. i got a great deal on a 6.0 at work so i picked it up. also the previous owner put hydraulic fluid in the shock. i dont even know what the weight was. but i figured the 6.0 spring and some fresh 3wt shock fluid is gonna be great for it.

[KDXGarage]

215 nekkid or 215 with all gear, tools, spares, water backpack, etc.??

I was thinking 5.4. You won't be close on the sag with a 6 Kg/mm rate spring.

[ridinredneck]

215 nekkid lol. i have always gone by what race tech suggests and its always been spot on for me. they said 5.75 and i know the 6.0 is a hair stiffer but i believe it will be ok.

[adam728]

If going in for a fluid change it would be very easy to pull a shim or two off the compression to soften it up.

With such a big jump in spring rate you are not going to want to soften rebound up. Typically when you raise the spring rate you increase rebound damping to compensate.

Fluid weight has only a very small effect on the damping unless doing an extreme change. I like to pick an oil and stick with it thru valving changes. One less variable. As said, Viscosity Index is the most important on a shock (which can run HOT). I eventually settled on running Maxima light (3W) shock oil. It's a good oil, is fairly cheap, and most importantly, is pretty easy to find!

As for using hydraulic fluid - that's all suspension oils are. On Thumpertalk there was some discussions on what some of what hydraulic oil some of the suspension oils actually are. Some tuners on there even admit to buying bulk hydraulic fluid with the properties they see as important and using it in everything with great results.

[ridinredneck]

well i must say that the shock is working awesome. static and race sag are good. it works way better and just floats over everything. the bike is just awesome thats all i can say. also got the bottom end lugging power back. put in some boysen 607 reeds and the kips detent ball and spring. the bike simply amazes me. no other way to put it.

[KDXGarage]

That is good. Thanks for the update.

[Nikwho]

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.

[billie_morini]

I used Race Tech Super Slick hydraulic oil Ultra Slick Shock Fluid in my KDX and DRZ shocks. This is a 5 weight 2.5 - 5W 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.

[KDXGarage]

Nikwho, have you seen what the spring rates are on modern off-road bikes? For example, a lighter YZ250X comes with 0.44. Guess what the ideal weight is for the bike. 175? 0.44 is not going to match up real well with your weight when fully geared up, much less all the other supplies. Nevermind 0.42.

I think with normal gear and your weight, you will be correct on the rear spring.

Is the stock valving set up from 30 years ago to match up with the butter soft springs? Yes. Will "modern thinking" "correct spring rates go well with old school damping? Not so much. It is really 2 problems, not just springs.

The job of the springs is to keep the combined weight of the rider and bike up at a certain level. Go get on a GoldWing. The spring rates went way up.You didn't gain an ounce, but the combined weight went way up.

Valve each end for your terrain, skill level, woods/off-road/ etc.

[billie_morini]

Ridinredneck:
in case you do not know, forum member KDXGarage (above) sells rear shock rebuild kits at a very fair price. I bought one from him and received these benefits:
1) didn't have to run around / spend lots of time chasing parts down
2) didn't have to worry that any of the parts wouldn't fit
3) knew all parts would fit because KDXGarage knows just about everything KDX-wise, suspension included
4) received all needed parts from one source and in one package
5) received valuable input for shock rebuild through direct communication with KDXGarage

[KDXGarage]

I used to sell the kits. :-)

I am not a know it all. Ha ha.

Thanks for the support, billie. I appreciate it.

[billie_morini]

Rideinredneck:
if you discover your new and any future rear shock springs have inner diameters greater than the stock shock spring seat outer diameters, then see the aluminum collars Race Tech made for me (photo). These collars allowed me to use the red spring Race Tech selected for me (rider weight, riding terrain & style, and stroke shortening). This red spring is straight rate (e.g, not progressive). I think it's rated at 5.0 kg 5.3 kg/mm. (will check records). Of course, if your new spring is same or near same length as OE spring, then collars you use would be thinner..

The collars are also spacers needed to assure frame geometry remained unchanged using the shorter red spring. Here's a photo of the blue OE spring and red aftermarket spring with collars.