1989 kdx 200 fork springs

[DanO]

Hello,

I have a 1989 kdx 200, put in racetech cartige emulators, softest setting, also racetech .40 kg springs and 7wt oil. It seems too stiff to me I think to get softer springs. Riders on this bike will vary quite a bit with weight, so I think to match stock rear for 180 lbs rider. Trail bike, low level riders.

Think to get .35 to around .37 kg springs . Will .37 springs be that big a change from .40 springs? I see a 1985 kx 250 set of fork springs at 37kg mm for sale ebay. I understand this will fit.

Any charts out there of stock springs on other bikes that will fit my bike?

Can't find new fork springs that seem to be what I want.

Thanks for any help.

[SS109]

I weigh 140lbs and I run .38 springs up front and 4.8 in the rear. For 180lb rider I would think .38's are way too soft but Racetech disagrees with me. I would try dropping to a 5 weight oil, or maybe reduce your oil height, or running less preload on the spring, or any combination of the three.

[DanO]

Wow, ok . From your info .40kg mm fork spring should be good. The area i mostly ride in is slow nasty rocky muddy, rooty trails. Walker valley orv in wa state.

When I compare the kdx to more modern ktms it seems too stiff. I already run low preload. Thinking on what to do. I assume the changes you suggest will let it have fuller range of motion as it works up and down, ie softer without a lesser spring.

Will do some thinking and research.

[kdxsully]

I’d switch the oil.

[SS109]

Hopefully one of our more knowledgeable than I KDX fork tuners will chime in here soon.

[DanO]

Trail riding over very rough ground is different than more open riding on mostly smooth ground. One can get away with very stiff suspension on smooth ground. I feel like a lessor spring is the way to go. But thinking to do the other mods first to see what I get.

[KDXGarage]

What is your weight in full riding gear?

How many millimeters of preload do you have it set at?

Do you bleed the air out of the forks before riding?

What is your oil height level?

I don't think going to a lighter oil is going to help much. A thicker oil in damping rod forks would help with rebound control.

[DanO]

Anyone have a list of stock fork springs from other bikes that will
fit a 1989 kdx 200? Or a place or method to find these?

I guess lower fork oil and more air on top will make a difference. But the compression force has to on go up, up as the forks are compressed. Jeff fredette has sure lower numbers for the fork springs ratings to be used.

The setting numbers I will look up when home, they are a bit lower than what racetech recommended. Rider weight will vary a lot from 160 with gear up to 210 with gear.

The orginal 30kg mm fork springs were too soft but .40kg is too big a jump to my mind. Thinking .36 kg to be the sweet spot for my usage.

[KDXGarage]

Is this a buddy bike or do you pack on weight for winter? :-)

If you want softer springs, try some .35's from someone who has changed springs in a 1995+ KDX.

Take off a fork boot and throw a lightly snug zip tie on there. See how much travel it is using.

I get you on the slow trail riding, but I am leaning towards a non-spring problem. Those cushy KTM's you mentioned do not come with butter springs. Even the KTM Freeride came with .44's.

If you are trying to get it to a 185 with gear (in the middle of 160 and 210), then 40 sounds about right to me.

[SS109]

Trail riding over very rough ground is different than more open riding on mostly smooth ground. One can get away with very stiff suspension on smooth ground. I feel like a lessor spring is the way to go. But thinking to do the other mods first to see what I get.

Yeah, vastly different terrains but my springs work for all situations. It's all about having the right spring for your weight, period. After that it's all about the valving.

I admit I gave up on the stock forks a long time ago so my thoughts are what works on more modern USD forks. Hence why I was hoping someone like KDXgarage would chime in He has lots of experience dialing in the stock forks.

[KDXGarage]

USD KYB A Kit or stock 1989 KDX200 conventional damper rod forks doesn't matter. The correct spring rate will be the correct spring rate.

[DanO]

Ok , I checked the 2011 ktm 300 xc w, 40kg mm and the 2008 ktm 300 xcw, 42kg mm . Both stock.

I am about 210lbs geared up and the 2008 ktm is about right for me at my skill. The 2011 ktm is buttery smooth, and is my wife's bike.

So from that the 40 kg shock on the kdx should be perfect but is stiffer than the ktms. The kdx was my wife's starter bike and decided to keep it as a buddy or backup bike for awhile.

So springs should be the same for all forks for a given weight ? If so I need to work on air level, preload, oil weight, and emulator setting.

[DanO]

Anyone have experience with racetech suggested settings? Are they good. My settings are close to what they suggest as far as I remember.

[DanO]

Maybe I put something together wrong? May need to go through the forks to check everything.

[KDXGarage]

It is my sincere hope that a 19 years or 22 years newer fork from a fairly more expensive dirt bike would work better than the 1989 KDX200 forks.

No amount of cash or parts will turn them into what you are used to riding.

I would make some small, cheap adjustments to try to better tune it to your needs.

Check that preload. 3 or 4 mm is good.

Any chance you know the Emulator spring rate? Any chance it is a street version instead of dirt? (stiffer spring rate to start with)

They do offer different rate springs for them.

[DanO]

Ok, I found my data, on my fork spring install.

5mm to 6.5 mm preload.
140mm air space.
Maximal fork oil 15 wt.

Race tech cartridge emulator. 3 turns, silver spring, which are light settings.

So I assume lower weight oil and less preload, any suggestions
Appreciated.

[kdxsully]

Changing the fork oil level can make a big difference too

[sarrant]

Did you drill out your damping rods when you installed the cartridge emulators?

[DanO]

Yeah I drilled the hole or holes. This is my first fork spring job but I have done most of my mechanic work all my life. I think maybe lighter oil is the main change I need to make.

[DanO]

Any suggestions for fork oil level?