96 KDX200 - Suspension Setup

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Charles
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96 KDX200 - Suspension Setup

Post by Charles »

Hello fellow KDX riders, I'm trying to set up my bike properly and I need some advice.

So I have a 1996 KDX 200 which is quasi-stock. Shock has been rebuilt in a local shop (Kayaba Shock Oil and nitrogen charge), Fork done twice (first by the shop then myself). All the bearings are new or serviceable, (wheels, steering, linkage and swingarm). Tires are new too so there should be only suspension tuning and riding technique issues.

This is the current setup:
Forks: -1 shim; 7.5wt Oil at 100mm. Compression clicker all the way out.
Shock: Compression clicker all the way out, rebound 8 clicks out.
Renthal 644 Enduro bars (wrong sweep angle), which will be replaced by 971RC bars.

I'm 152Lbs and 5'7" without gear. I'm new to offroad and I'm doing enduro riding in rural France. On the "hard" side of enduro, not MX (but why not, one day) . We do a lot of hard, muddy wet rocks and roots sections. Well, at least I'm trying.

This is the issues I have with the bike:

Rear:
-Too much free sag (about 70mm) to obtain a race sag of 100mm.
-The bike tends to kick me out on hits. I had to fully open the compression and limit the rebound to correct this
-I have trouble compressing the rear with my bodyweight while passing obstacles.

This seems to be caused by a stiff shock spring. Am I correct?
Racetech calculator leads me towards a 4.8Kg/mm shock spring. Fredette's recommendation says I'm in the middle of 4.6 and 4.8 springs.
What would be your advice? Also, is this easy to replace? I have access to Hyperpro and Yacougar springs 4.8 for about 100€, or a racetech 4.6 for 160€.

Front:
-The bike feels quite twitchy compared to others I've ridden (even my wife's 99 Husqvarna). It doesn't have the "railroad track" feeling.
-It has a tendency to deflect over small obstacles, the worst being riding a track made of fist-sized rocks.I really have to put my head forward and grip the bike hard with the knees to keep it vaguely in line. Unfortunately we do a lot of these.
-In bigger rocky sections (football size and more), it will deflect a lot and is very hard to control. We do a lot of these too, with mud everywhere. This is where I struggle the most.

What should I do with the forks? Removing the shim did some good. Should I remove more shims? Try harder springs? Won't that make the front even more twitchy?
Racetech calculators find .36 to .38 springs (C-class or B-class rider). I'm surprised not to find sag measurements to calculate front fork springs?


I'm considering a front end swap but parts and shop work are very expensive here. Also KX parts are not so common in france. That means I would need to find a decently priced enduro front-end, of full chassis from a WRF or an EXC but that's unlikely to happen soon.

Thnaks in advance.
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Re: 96 KDX200 - Suspension Setup

Post by Slick_Nick »

Your problem is that you're too far out on the compression. You've effectively eliminated ANY damping by bypassing the compression valving front and back. You need MORE compression damping. Stop removing shims.

When you're too far out on clickers, there will be zero damping until you're deep into the stroke, where you'll end up smashing into bottoming cones and shock bumpers, causing the suspension to kick, deflect, and buck you around. This is dangerous, you can be hurt.

You are trying to control this harshness and bucking by slowing down the rebound, which is the opposite of what you want to do. I'm sure your bike is unrideable, or at the very least quite uncomfortable. The stock spring rates should be fine for a rider of your weight. Go back to stock clicker settings on the shock and fork, and go ride it. I'm willing to bet you will notice a huge improvement.
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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

Go to 10 - 12 on compression on both ends, with rebound on the shock set to normal per the manual.

I think a 4.8 would be better. .38 on forks would be better than stock, but the current rates are not super far off. I'd get the clickers set correctly first.

Next time, try 5 weight oil (stock).
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Re: 96 KDX200 - Suspension Setup

Post by SS109 »

I agree with what both have said above. Sometimes it seems counterintuitive but too little compression and/or rebound will actually make the suspension much harsher.

For comparison, I'm 140lbs and run .40 in the forks and a 4.8 in the rear on my KDX and .38/4.8 on my GasGas and both setups seem perfect for me, a mid-pack B racer/rider. I ride some pretty fast stuff but also a lot of slower rocky technical stuff as well. You can check out what I ride vs what you do by checking out my Youtube channel in my signature.
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Thank you guys for your answers. I took the bike for a solo ride this morning, without touching the settings. Once warmed up, I put ut the following clicks:

Fork Comp. 10
Shock Comp 13
Shock Rebound 13

As you expected, it did'nt make the suspension harsher and I'm now headed in the right direction.
I had trouble analysing the results, the terrain veing very muddy and slippery today but I managed to get 4th gear down little rocky sections. I did not try hard-enduro style obstacles as I was alone. I did'nt dare to push hard enough to bottom out the suspensions.

But,

The rear feeling is improved and seems to kick and rebound less. I still find it a bit hard overall.

The front is a bit more stable but still has a tendency to deflect over single hits.

I'll definitely try 5wt oil soon, and maybe a lighter rear spring.

What would harder fork springs change to the bike's handling? I don't seem to need them as bad as I can read everywhere on the forum but maybe I'm still too much of a beginner

SS109, I had a look at your videos, awesome desert stuff... we don't get that in France. What we do is more... "muddy and wet". I'll try making some videos one day
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Re: 96 KDX200 - Suspension Setup

Post by Slick_Nick »

Springs are basically for your weight only. You control plushness and suspension action with the valving, but having said that, if the springs are too soft, you end up too deep in the stroke no matter what you do and the valving is harsh, so they do work hand in hand, sorta.

With your weight though, I would think you're ok with stock springs.
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Re: 96 KDX200 - Suspension Setup

Post by MoonStomper »

Sounds like the boys have pointed you in the right direction. I’d only add the recommendation that you consider sending your forks to Racetech for their Gold Valves or GoRace for their Belgian Valves. You can also order and install these yourself if you have access to some suspension tools. Dumping those shim stacks for Belgian Valves totally changed the way my forks felt, much improved confidence and control at race speed.
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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

Charles
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bottom line :-)
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Hi guys, I'm back at working the KDX.

I'm shopping for a rear spring today. I have acces to a racetech spring (kdx specific) at a great price, but only the 4.6. Is it really too weak for my weight?
With the stock one 5Kg I have 70mm+ of free sag to obtain 100mm race sag so it's way too hard.
I'd like to have something around 35-40mm of free sag with 100mm race sag.

The 4.8 sprigs I have access to are not KDX specific (Hyperpro or Yacugar brand, they claim to fit all Japanese dirt bikes) and I'm worried about fitting issues.


I do consider Gold valves for the forks but they're too expensive to get here. Also, suspension shops here are only interested in top-end expensive stuff. I'll try changing the springs after finishing the rear shock.

I've got a few nice events coming this year, the first one in march, a friendly meeting/coaching week end at a beach sand track!
At Loon-Plage, it's a known place used by the Enduropale du Touquet (tough sand mx endurance race) riders to train all year. I need my little KDX in tune for when I get there =)
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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

See if the Hyperco comes with a spring adapter. I would think 4.8.

I am thinking .36 or .38 is not enough. Look at what current bikes come with. A Yamaha YZ250X comes with 0.44 I think. Spring rate thinking has changed over the years. A KDX is a fair bit heavier than a YZ250X.
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

I don't think the hyperpro comes with an adapter.

It's the model SL-MO-450-48. Their catalog says it also fits YZ's and KX 125, 250 (88-10), Suzuki RMX 250 89-97, and a few others.

Do I need an adapter? Is it easy to make?


For the fork springs I'll have them custom made, it's not very expensive, about 110 euros.
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

The springs will be too large for a 1995+ KDX shock without an adapter ring to take up the space.

Race Tech springs used to come with them, but have not for a while. Race Tech sells adapters.

See what Technical Touch in Belgium offers.
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Thanks for your precision.

I found Racetech's list of spacers. They're available on ebay but at really exaggerated prices.
Technical touch, very nice link! They are asking quite a lot too.

This feels like quite a bit of money for a spring. Look what I found:

https://www.ebay.fr/itm/AMORTISSEUR-250 ... 639-2357-0

That could be an easier solution, gasgas parts are everywhere here. I found a thread here with a list that says it should fit...
Being an enduro shock it should do the trick in terms of valving?

Sorry to ask so much questions...
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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

I would pass on getting a different shock. That adds a lot more questions than answers. The valving may be way off for the KDX swingarm and linkage.
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Re: 96 KDX200 - Suspension Setup

Post by SS109 »

As someone who has done a rear shock change, it's a little more complicated than just swapping in another one. Overall length, length of travel, lower clevis shape, attachment, and length, upper shock attachment width and bolt diameter size, diameter of the spring it uses, and the location and diameter of the reservoir, and the internal valving, all matter. Binding and rubbing are issues you have to watch out for as well. It is much easier, and cheaper, to get a spring and the appropriate adapter.

See, when I did my swap, I used an '01-'06 Suzuki RM125 shock but it uses a modified Honda XR400 lower clevis and I had it built by a professional suspension guy I have been using for 10+ years and trust 100%. I still didn't know if it would truly work until after the shock was already built and I tried to install it. That's when I found that the lower clevis needed to be modified. It was an expensive gamble at about $400 US, and well worth it IMO, but it has to be done right or don't do it.

Speaking of GasGas and spring adapters, that's what I had to do on my '11 GG EC250R Racing to get a 4.8 KYB spring to fit instead of trying to find the expensive and, at the time, unavailable Ohlins spring I needed.
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Yeah, you're right. I was a bit carried away on that one.

The kid is sick today so I'll go shopping for a spring and an adapter.
If I can't find a reasonable adapter I'll try to have one made either on a lathe or maybe welding a piece of tube and a big washer
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Re: 96 KDX200 - Suspension Setup

Post by SS109 »

I know Racetech has the adapters.
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Got a nice answer from them, they'll ship to France but at 65$ + french custom taxes it's too much for me.

I just ordered a 100$ 4.8Kg Hyperpro spring.
I'll make an adapter somehow =)
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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

Sounds good. Good luck.
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