1989 kdx 200 fork springs

[DanO]

I am thinking to take apart recheck it all. Keep emulators at light settings. Use 5 to 7 wt oil. 3mm preload. Air level above oil I have no clue as of yet.

[DanO]

Working through this, 15 weight oil is likely my big problem. Has anyone tried 5wt verses 7.5 wt oil by mixing 5 and 10 wt oil ?

[SS109]

Has anyone tried 5wt verses 7.5 wt oil by mixing 5 and 10 wt oil ?

Yes, lots of people have done it.

[KDXGarage]

Hmm. 15. It is cheap to change and see how it goes.

Your other settings sound very reasonable.

Sorry to sound like a dork, but I say just change one thing, then see how it goes. If you change three things, you won't have a clue what the problem was.

Jeff Fredette used to suggest 7 weight oil in the forks. Mixing 5 and 10 would work. 10 is not twice as thick as 5, I think.

Perhaps the Emulators are sensitive to viscosity? I always read that in normal daming rod forks, greater viscosity helped to control rebound.

Please let us know how it goes. I hardly ever see any "fork stories" that are on the damping rod forks.

[DanO]

https://www.racetech.com/page/title/Emu ... hey%20Work

Rebound damping with emulators is supposed to be controlled only by oil. To control compression damping, the emulator has different springs and a screw, to control spring tension.

So this my thinking you set rebound damping by oil wt, then fiddle with emulator settings to get the compression damping you want. To do this take out springs and fish out emulators with hook wire to adjust, try it again etc.

My bike seems a bit stiff to me so lighter wt oil and see what I get. I imagine Jeff fredettes oil wt setting is for damping rod forks so dont know how that translates to emulators.

Thanks everyone. It be awhile before I can work on it, when I do, i will come back to this thread to report.

[KDXGarage]

That is what I was thinking.

They used to make four different rate sprigs for them. Check on that.

Good luck with it, and thanks for the future report.

[kdxdazz]

Definitely change out to a lighter oil, the oil determines the compression as well as the rebound, if most of what you do is knarly single track then try 5 weight or even 3 weight

[DanO]

Ok, I put in 7.5 weight oil, while doing this I tried to put in new front brake pads. The front caliper was shot all the rubber rotted. So ordered a rebuild kit. Could only find a rebuild kit out of UK. It took over a month to get to me due to Covid 19 madness. Finally got it put back together. Still too stiff as compared to the ktm 300 xcw bikes that we have.

I just ordered .36kg front springs off off Ebay used out of a 2000 kdx 200.

I plan to keep the 7.5 weight oil and use the H series spring in my 1989 kdx 200 E series bike. As I understand it is suppose to fit.

I think the .36kg spring to match the rear. The race tech .40 kg spring does not match the rear.

For anyone wanting a small upgrade for a 1989 kdx 200. For play riding i suggest using stock fork rebuild it and use .35kg front springs if you can find them. Plus or minus kg a few kg.

If your very heavy like 230lbs and up maybe the 40kg front springs with a stiffer rear spring.

This is for normal trail riding with average rider.

[svboy]

Here are my thoughts-based on H model forks. I have no experience of the impact of an emulator nor of 89 spec forks.
Stiffness will be a function of spring rate, oil weight and compression valving. If you have checked your rider and free sags for the front of your bike, and they are correct, then that spring rate is correct for your weight. Changing to a lower spring rate wont help as you will not be able to reach your correct sags. Oil weight is an easy fix- experiment 5w, see what happens. If your spring rate is correct then have your compression stack revalved. Not a big job and possibly the cause of your stiffness.
Fork oil level will affect rebound, so changing the level will either speed up[more fork oil] or slow down rebound[less fork oil], not soften compression. Start with what the manual says and experiment. You want rebound on a dirt bike to be fast and responsive, so it returns the wheel quickly to the surface, rather than slowly, bouncing from bump to bump.