Kdx200 doesn't ride so well

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actmobmar
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Kdx200 doesn't ride so well

Post by actmobmar »

Haven't ridden in a few years, so some of this may be me. Bike has a real harsh ride, especially low speed riding and doesn't seem to track so well in hardback sand or dirt (I actually don't feel comfortable riding it fast on that ), in grass hi speed is ok. I rode my son's drz400 and it is nite and day better. Set rear sag to 3.5", reR shock 8 clicks out, bike has kx 250 forks, top adjustment all the way out, bottom adjust 2 clicks in. At hi speed in bumpy conditions it isn't bad, but low speed it's like a truck!
actmobmar
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Re: Kdx200 doesn't ride so well

Post by actmobmar »

Bike also seems like it tracks real bad in small ruts and it isn't stable at hi speed in hardpack sand or dirt, tires are good, and the drz doesn't do this. Thanks!
sarrant
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Kdx200 doesn't ride so well

Post by sarrant »

The KX forks with stock valving aren't ever going to be close to as compliant for low speed and small stuff as DR/KDX forks. They're valved for big jumps. Look into what shim stacks are being run for trail riding.
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Jaguar
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Kdx200 doesn't ride so well

Post by Jaguar »

Keep in mind that the front fork angle is steeper on the KDX than a motocross bike which affects the way it behaves.
Steeper is better for tight technical trails but worse at high speed.
When I modified mine for MX I lowered the rear and lengthened the front to give it more angle and better stability. Before than it wanted to swap ends on the track.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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kawagumby
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Kdx200 doesn't ride so well

Post by kawagumby »

It's all about setup.
1.Make sure the KX forks are setup at the right height in the triples - those forks are longer than the stock kdx and must be set higher in the triples to have the correct riding geometry. I set my forks about 1" above the top of the triple to the top of the fork. You can adjust further once you check it out on the trail.
2. Set your rear sag to about 4" not 3.5". You can go from there once you get some trail feedback. You didn't say what year kdx, but if it's a 95 up, the rear spring will be on the stiff side if you weigh under 170 or so. So it might be that you have a stiffer spring than is optimal, with only 3.5" of sag compounding the problem.
3. Set your shock rebound so when you push down on the seat, it has just a touch of noticeable drag returning. You can adjust further on the trail...
4. Set your shock compression to about center to start.
5. Make sure your forks are setup for trail riding. Are the springs the right rate for you? If they are off a 250 and you weigh less than 170 they are probably too stiff. Most riders under 170 lbs prefer 40's or less spring rate. Has the compression stack been revalved for trail riding? If not, they need to be modified. You can try doing it yourself by checking the fork conversion forum and seeing what other guys do. In reality tho', you can probably get away with removing about half the larger diameter shims and using 2.5 wt oil (like amsoil light 5) set 120mm from the top of the compressed fork housing (spring removed). Once modified with the lighter oil, set the fork rebound to center for a start, then check on the trail.

You should see a noticeable improvement just moving the forks up in the triples (if they're not already) and having the fork rebound (top adjustment) centered to start even with the KX forks being stock... you want to control the heavier spring rebound in the rough so the bike won't buck so much. The compression (bottom adjustment ) should probably be all the way out (least compression).




Hope that helps.
Last edited by kawagumby on 08:30 pm Jun 22 2015, edited 2 times in total.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
actmobmar
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Re: Kdx200 doesn't ride so well

Post by actmobmar »

Currently the top of the forks are just about touching the bottom of the handlebars. On the rear shock if you continue to turn the adjusters counterclockwise shouldn't there be a stop like the front forks have?
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Kdx200 doesn't ride so well

Post by Jaguar »

almost touching the handle bars means you've made the front end even more steep, the opposite of what you want.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
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kawagumby
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Re: Kdx200 doesn't ride so well

Post by kawagumby »

actmobmar wrote:Currently the top of the forks are just about touching the bottom of the handlebars. On the rear shock if you continue to turn the adjusters counterclockwise shouldn't there be a stop like the front forks have?
You need to get the right geometry by raising the longer KX forks in the triples (if they haven't been shortened to reflect the stock fork length). If the forks haven't been shortened or raised in the triples, the combination of the stiffer springs and longer fork length will make the bike very hard to turn...it will "push" the front end in turns (lose tire grip) and not handle rough terrain well at all. I've done several USD conversions and all have had to be raised about an inch +/- depending on the fork spring rates and preload. If you don't have bar risers, or aren't using fatbar adapters (which act like risers) you probably aren't able to get the forks high enough because they will hit the bars...is that the case?

With regard to the rear shock, yes, the adjusters should stop when fully rotated out or in.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
actmobmar
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Kdx200 doesn't ride so well

Post by actmobmar »

is there any specific measurements in reguard to the front forks to see if they have been shortened? how do i set this up properly, and do i need to change the front springs? i rode the drz for a bit yesterday again, and it makes me realize how bad my kdx handles and rides.
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kawagumby
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Re: Kdx200 doesn't ride so well

Post by kawagumby »

The fully extended stock fork is about 36 3/8" long from the center of the axle to the very top of the fork.

You can check the spring rate. Do a search in the fork conversion section, I think that process is described there. However, what I would do is change the oil to 2.5 wt (amsoil light 5) at 120 mm. Then make sure they are the right position in the triples. Center the rebound, all the way out on the compression. See how they work, go from there. If you do end up wanting lighter springs, you can probably get a cheap set of used KX125 springs off of ebay - but make sure they come from the same fork design.
Last edited by kawagumby on 07:47 pm Jun 22 2015, edited 1 time in total.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
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Jaguar
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Kdx200 doesn't ride so well

Post by Jaguar »

Just get a protractor and a carpenters level to determine the fork angle. Target around 30 degrees from vertical.
Use the level to find a level surface for the bike. Then let a weighted string hang from the bottom triple clamps as your vertical reference for the protractor. Use it to see the fork angle.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
sarrant
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Kdx200 doesn't ride so well

Post by sarrant »

Jaguar wrote:almost touching the handle bars means you've made the front end even more steep, the opposite of what you want.
His bike has KX forks. They're enough longer that even pushed up to the bars (without bar risers or internal fork modification), they will increase rake over stock quite a bit.
actmobmar
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Re: Kdx200 doesn't ride so well

Post by actmobmar »

I appreciate all the help guys, I know engines well but am lost with the suspension part!
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