96 KDX200 - Suspension Setup

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MoonStomper
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Re: 96 KDX200 - Suspension Setup

Post by MoonStomper »

Your over stiff rear spring is pushing your forks deeper into compression which is contributory to your deflection issues up front. This out of balance condition is your whole issue. More compression in the forks will reduce deflection. Stiffer springs up front would definitely help rebalance the bike, this will take care of the deflection problem, but if you can’t achieve proper sag the bike may feel over stiff and you won’t be fully utilizing the potential of the design - unless you are riding fast and aggressively enough to overcome the spring’s rating, which fast B and A riders will do.

You are riding fast in rocky and wet terrain which sounds similar to what we have here in southwest Virginia. The 4.6 KDX spring is what I would go with. Set your sag up, then dial a little more compression into your forks. I’d stick with the heavier weight fork oil, but don’t be afraid to test the 5wt.

Lastly, what tire pressures are you running? Heavy duty tubes? I’ve had very good success running lower pressures (F @ 11psi / 8psi R) with heavy duty tubes. This is with a 110/100-18 rear.

Trying that 4.6 set at proper sag with your current fork springs and 7.5 wt fork oil might just be your ticket.
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Thanks for your input.

While waiting for my 4.8 to arrive I found myself a copy of Racetech's suspension bible. I higly recommend it, it's very well written and easy to understand. I ate the 258 pages in one sitting, it's written a bit like the technical training manuals for aircrafts. Their paragraphs explaining the low/high speed compression circuits is really helpful. The preload / sag / spring rate also is very nice to learn.


Guys, I think we're headed good: both your inputs, and what the book says seems to converge.


MoonStomper, I read what you're saying in the book: Get the rear sag first before working up the front or modifying stuff. So I'll do that.

I received my 4.8 spring. It's tapered and maybe will fit without too much of a hassle. As soon as I can install it, I'll measure the Free Sag with a basic 100-110mm Race Sag. If not enough maybe I'll go down to 4.6.

We will then be able to determine if harder fork springs are necessary. Racetech's calculator heads me towards a .38 but we're not there yet.
I'll try adding low speed comp. and playing with the shim stack after the basics are done.


As for tire and pressures, front Metzeler SixDays 90/90/21 at 13psi; rear Michelin Tracker 120/90/18 at 11.5Psi, Heavy duty tubes (4mm maybe). Maybe I'm a little too high.
Michelin Trackers are "leisure offroad" tires and not meant to cope with hard enduro low pressures, I'll get rid of that.


By the way, I looked up "west virginia hard enduro" on Youtube, and yes, we are riding the same kind of rough, wet, muddy, slippery, steep nightmare :supz:
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Re: 96 KDX200 - Suspension Setup

Post by MoonStomper »

The Race Tech book is what I read too. It is a great teacher of suspension concepts. The balance of your suspension is probably the most important thing. If you get that right, the rest is just fine tuning.
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Re: 96 KDX200 - Suspension Setup

Post by doakley »

Your tire pressures seem high to me, especially with HD tubes, even for rocky courses. I ran mine as low as 7-8 psi in sandy/muddy locals but never over 10, even in the rockiest mountain tracks (with HD tubes of course). Only had one flat (rear) and was able to ride it out.
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Re: 96 KDX200 - Suspension Setup

Post by Slick_Nick »

Yeah 12psi is a tad high for a trail bike. Try 8 or so.
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Re: 96 KDX200 - Suspension Setup

Post by SS109 »

Yep, lower the pressure the better if your tube and tire can handle it. Well, not in all situations and tires. The Goldentyre fatty fronts like 11-12psi from what I've found. Any lower and they start to wallow a bit. You gotta experiment a bit to see what works for your combo.
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

I worked the KDX for an hour tonight. I made some measurements:

155Lbs rider:
5Kg Stock Spring, 100mm Sag with gear , 50+mm free sag
4.8Kg Hyperpro Spring, 35mm free sag => 90mm Race Sage without gear (should be around 100 full gear)

Seems like it's the correct weight, am I right? Racetechs bible give a large tolerance for free sag: 15-40mm that should also be correct with a 4.6


HOWEVER, the springs are not the same diameter and lenght

Stock ID 56mm at tapered end, 62mm at straight end (adjuster side), lenght 255mm
Hyperpro ID 59mm tapered, 64mm straight, lenght 275mm.

It did fit though, and with preload it does not move... I will try to find an adapter.
Tomorrow I'll take a quick ride and report. Static in the garage, it does feel softer under my weight.
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Re: 96 KDX200 - Suspension Setup

Post by SS109 »

90mm race sag seems way off to me. It's recommended to be close to 100mm race sag with 30-40mm static sag. 10mm is a huge swing. I think I'm running 103mm on a 4.8 at 140lbs no gear.

Setting sag.jpg
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Setting sag 2.jpg
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

SS109, yes, I am shooting for 100mm race with 30-40mm static.

Last night I had no gear on, so I worked the other way around. I set the static sag first to 35mm.
Out of curiosity I then measured the race sag, without wearing any gear.
Don't worry, before riding I'll adjust it properly with gear on but I think the weight of the full boots, protectors, helmet backpack etc should cover the missing 10mm
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Wow! Why did I wait so long to perform this modification?

With the 4.8 spring I'm at 100mm race sag, with 37mm static sag. I kept my usual tire pressures (on step at a time!)
I went for a two hours solo ride (only soft stuff) on tracks I know well. Variety of terrain, grass, loose soil, mud, rocks, hardpack, small logs, a few uphills and downhills but nothing difficult.

The improvement is massive! I can feel the wheels working up and down on the bike instead of kicking me in the air. "Tricky" (for me..) 2nd gear rough sections are now considered 4th gear easy trails. I did not expect such a change.

Also it's A LOT easier to do hill starts, to find grip on hills and to not lock up the wheels on downhills.

As Moonstomper predicted, having the correct rear spring rate allows the fork to work in a much better way. I'm not deflecting on peebles anymore, the bike is way plushier to ride and I can hit holes at speed.
I still feel that to be perfect, a tad bit less high compression would be nice, and as I built my speed up and up during the ride I sometimes think I feel slightly harder springs with less preload would be nice on the front. Rear 4.6 Spring could also be something to try for hard stuff.
But I've got plenty of technique to learn first, I'll do the training camps with this setup.


Honestly, I wonder how I was able to ride the bike before. It's the first time I feel like riding a properly working dirt bike.
All that for a 0.2Kg/mm difference.

Thanks a lot guys, I'm loving that bike!
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Re: 96 KDX200 - Suspension Setup

Post by SS109 »

Congrats! Now you understand the importance of bike setup. IMO, suspension is everything on a dirt bike.

I would stay away from a 4.6. I'm 140 without gear and a 4.8 is perfect and you're 15 pounds heavier than me. With a 4.6 I would be bottoming all the time and there is no way the sag numbers would be right which would jack up the handling.

Now, you can start playing with fork height! :mrgreen:
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Re: 96 KDX200 - Suspension Setup

Post by MoonStomper »

Glad to read your report, this site (and the experience and ideas of the people driving it) is such an awesome resource I can’t imagine how we’d get along so well without it.
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Let the good times ROLL!!!!!!!!!!!!!!!!
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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

Congratulations on getting it swapped over. Do check on some stiffer fork springs.

Enjoy!
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Little piece of information.

I got an answer from Racetech about spacers. I sent them the dimensions of both springs. For them, 3mm difference in spring inner diameter should not require a spacer. Yesterday everything stayed good while riding but I'ts nice to have their opinion on this.

Meanwhile,
I checked the parts diagram and found that KX 125-250-500 from the 90's, which the Hyperpro Srping should fit on, use the same "cup" as the KDX (on the clevis side of the spring), Ref. 13070-1165, but with an additional spacer. Ref. 13070-1161.
The adjusting and locking nuts are the same on Kx's and KDX.
I was not able to find this part on ebay or on Kawasaki parts dealers. If I come across a cheap beaten-up KX shock I'll buy it to get the spacer but it's an unlikely event.
It's kind of useless also, the spring works fine without it and the part is not slotted so it will maybe require removal of the clevis.
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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

You don't have to remove the clevis to put on that spring guide.

It is available in the USA. $13.77 at Partzilla.

https://www.partzilla.com/product/kawas ... 31e9faadc0

The 1989 - 1994 KDX200 and other models came with it.

https://www.partzilla.com/catalog/kawas ... k-absorber

Image
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Hello guys,

I did my first "real" ride with the new spring. Settings: Fork comp 10, Shock Comp. 13, Rebound 13.
I was invited by a group of very experienced riders, who mostly do reconaissance for the local events (races and meetings). They actually traced the trail of the first meeting I did last September which was a real struggle for me. (111 miles of wet muddy rocks.. tough for a first ride)

So off we went last saturday, at dawn with -5 degrees. The fastest guy had a 300 2st GasGas, there was a 72 years old ex-racer with a 4st 300 Sherco, and a former KDX rider with a brand new 300 2st Beta who closed the ride. Owns a hybrid 250CR frame with 220 engine, insane.
We did 60 miles of tough rocky stuff, to prepare the next local event.

Well, I'm proud to say that I passed all the difficulties with the old KDX!! Except one really tough climb with steps and roots. Even my experienced colleague had trouble climbing it with the KDX, but after a few fails we decided to move away from that one.

We took rock gardens, which were a nightmare before, and the bike went through with much less deflection and arm shaking. I'm starting to learn 1st gear clutch control, yeah!
I was also more confident in the open sections, swiftly cruising in 4th / 5th gear.

Honestly the Kawa feels capable, I feel like the difference with the new bikes is the amount of effort needed. The guy on the brand new Beta could lazily get through stuff sitting down, the bike ate everything! Or maybe he was just very talented :hmm:
The new bikes are also much thinner, so they feel lower even if they have similar seat height.

I had the most experienced guy try the KDX.
He thought the bike was soft enough to do hard stuff, and helped me find the torquiest revs of the engine. The 200 likes a bit of revs to get through stuff.
However, we quickly found the limits of the rear tire (Michelin Tracker), which is a "Road-Legal Motocross and Enduro Leisure" tire.
It is way harder than the Michelin Enduro Medium they use, and is not supposed to be used with less than 14 Psi :blink: As soon as I'll finish it I'll try to fit something soft, and with a Mousse. The Tracker is not suited to find grip on wet rock faces, or greasy mud. However for "not hard" enduro it's very good, durable, cheap and does not fear tarmac sections.


I really want to try harder springs in the front too. On braking, the front dives a lot, and I feel that harder front springs should get the forks up a bit and get the bike more balanced and softer on the fast compression. Am I correct?

Is .38 or .40 springs WITHOUT Gold Valves a know working setup?
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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

What is your weight in full gear, water backpack, extra tools, extra parts, etc.?

If you get 38 or 40, you will only know it is a lot better than what you have now. It won't be correct, but it will be better.
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Re: 96 KDX200 - Suspension Setup

Post by bufftester »

The front suspension also has race and static sag that should be set, just as with the rear. Without doing that the bike will be unbalanced. IIRC forks on the KDX were like 25mm static, 85mm rider or somewhere in that range. Rule of thumb is rider sag should be about 30% of travel in front, 25% in rear, statics 25 front, 30 rear. As with all things its just a starting point to get to your preference. But as mentioned by others, money spent on suspension is the biggest bang for your buck/.
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Re: 96 KDX200 - Suspension Setup

Post by Charles »

Sorry for the late answer,

KDXgarage, I don't know my full gear weight but I'll measure it!

Bufftester, I'll try to measure the front sag to get a starting point.

Racetech bibles advises 60-75mm race sag, with 3-15mm preload. They do not mention free sag for the front. 25mm as you mention seems realistic to me.
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Re: 96 KDX200 - Suspension Setup

Post by KDXGarage »

Race Tech suggests 4 mm on their product search page. From reading comments from a few paid tuners, they don't do the big preload anymore.

I think stock preload on the 1995 + is 38 mm!
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