Stiffening up the suspension for jumps

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Johnny
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Stiffening up the suspension for jumps

Post by Johnny »

Hey fellas, I am new here but I have noticed that when I jump the suspension is really soft. I understand that the KDX220 is not a MX bike but I want to have the best of both worlds. I currently have Race tech springs up front and stock rear spring. I love the way the bike handles in rough terrain, but I just want to stiffen it up a little. Is is as simple as increasing the pre load on the rear spring and clicking up the rebound? Or is there something bigger I should be considering like a whole new spring/forks set up? I am 175 pounds fully geared. My bike is street legal and the liscense plate hangs below the tail. When I land jumps the plate actually hits the rear wheel and now it has a permenant bend in it.
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Indawoods
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Post by Indawoods »

KX forks and a Gold valve setup in the rear will do wonders.

License plate and jumping don't mix. Think about removing the plate. Your rear suspension is supposed to react that way.
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Post by AZRickD »

I've noticed when I follow riders over jumps at the same speed, they get lots of air and I just kind of mush through them. Sometimes I have to pre-load my front forks to get a good pop over the bump. Almost like I'm being robbed of some fun factor.

I might have the KX fork mod done by next weekend if the parts all come next week.

We'll see if that helps matters.

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I done KX-ed QuailChaser's KDX220R
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skipro3
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Post by skipro3 »

It takes rider input to preload and hop the bike into the air. Also, snapping the throttle at the right moment will kick her a bit higher too. Somewhere are some videos of Trev table topping his KDX. I think it was a 45 foot tabletop. Not bad with a rider that's at least 6'6" tall!!!!
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Colorado Mike
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Post by Colorado Mike »

The difference between a trail bike and an MXer on jumps is huge. I rode my son's YZ on a stretch of trail that was whooped out. On my KDX I would hit tree branches occasionally with my helmet. On the YZ, I had the rude experience of getting hit with heavy branches across the arms and chest. I was sailnig a good 2-3 feet higher just over the whoops. The reason? much stiffer suspension, about 30 lbs. less weight in the YZ, and probably going a bit faster due to the much better handling of a 1 year old design over a 15 year old one.

Since I have access to both, my KDX is not the bike I pick for jumps.

Since you are looking for a compromize on the KDX, I would say go to a stiffer rear spring with the expectation that it may throw the front out and make it seem too soft. Then do the KX conversion to the front. :lol: This will give you a reliable, porky, comfy pseudo-MX looking bike that won't kill you as easily on the track, but will be much better handling on the trails. :supz:
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thebleakness
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Post by thebleakness »

Ive been having the same problem jumping my KDX. I hit the jump and the front rolls over resulting me to almost endo. Then i try the same jump at the same speed with a friends KTM 250ex and its wonderfull. My front suspension has been adjusted and should be much stiffer than the stock shocks, which brings me to the KX forks. How does that effect trail riding? Are they better than the KDX forks over ruff terrain and then also better for jumping? I would assume there is a trade off somewhere because if they KX forks are that much better they would have put them on the KDX in the first place...

Or i could be wrong in that assumption. Ive been thinking about that conversion and that question keeps coming up.
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Post by bradf »

The trade off is price. KX forks cost significantly more than KDX forks. The KDX forks are old technology, small and rather simple. Kawi kept the cost down on the KDX by running virtually the same frame and parts for years. The KX forks are better in every way on every surface in every condition. To a large extent, the newer the KX fork, the better they became. They also got larger as did all the USD forks. KX forks have more bottoming resistance, more dampening adjustability, wider dampening control and stiffer mechanically. So yes they are better, WAY better.
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Post by Jeb »

>|<>QBB<
bradf wrote: . . . KX forks are better in every way on every surface in every condition . . .
Wait a minute - KX forks, or newer mx forks in general, are more advanced in technology and are better in that sense, but are they really better in all circumstances? :neutral: I know at a local harescramble club the guys claimed that those who get mx bikes for the woods have to send the forks away to be "tuned" softer, revalved I believe. This costs hundreds of dollars yet some are willing to do it because some like the mx trannies better . . . but then they have trouble on mx tracks 'cause now the forks are too soft :?
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Post by motorhed220 »

K, i have never had a problem with air, in fact, i think the only problem with my KDX suspension is the fact that it almost ALWAYS bottoms out on the front end...Thats why i plan to get the KX forks...But as for jumps, its ALL technique...

sure if your on the high quality MX tracks that are super maintained and all hyper set up FOR MXers then yea, a KDX is out of its element and not going to compare to the MX bikes...over all...but it will give em a run for their money i find...

BUT...if your on locally built or homebuilt tracks and modest tracks, the KDX can do just fine....Technique is EVErYTHING for jumps...I have blown past guys on MX bikes, not because my KDX is better, but because the MX guys dont hit the jumps at the right speed or time everything right...

Try hitting a Jump (depending on the run you have, and your nerve) at say 3rd or even 2nd gear, make sure your on the throttle till you are at the base of the jump, then ease off and glide over the jump ( do this on a small jump or a modest one)

use your common sense, if you can build the jump with your shovel, then you dont need to be past 2nd gear. If its bigger, dont got past 3rd gear but only if you have a run at it, otherwise you will need your second gear for the torgue to get your bike at the right speed. Endoing a jump happens (on a 2 stroke) when you lay off the throttle way to soon...

guys its all or nothing, either you are on the throttle at the base of jump, or your on it while your leaveing the jump (that gives you distance and hight) otherwise, dont even think abou letting off the gas before you hit the jump, unless your flying...Member, if you want to fly with the birds, you gotta have the balls and the timing nailed, toherwise dont try it...

Finally, i dont know what kind of KDX your on, but the reason for my jumpin sucees is because i have a 2005 KDX, if your running a 15 year old bike, tyhen yea, your toast...weight, and the technology simply isnt there. I dont care what ANYONE says, a 2005 KDX is a WHOLE different animal then one from 15 years ago.Period. But that is about all there is to jumps...CHEERS!!!
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Post by bradf »

A KDX is “out of the box” has an unbalanced suspension. The forks are sprung for a 140 lb rider while the rear is sprung for a 180 lb rider. There is $100 to fix that. The forks by design can’t take the beating the newer USD forks can due to weak physical design as well as lacking internally. “If” you want to ride a pokey pace on a nice fairly smooth fire road or trail and you never demand more from the forks past their ability, then you don’t need different forks. You can save a ton of money by not getting a KDX altogether and look for a 69 Bultaco Matador, cheap! It has forks. It has shocks. It has twice the shocks! I don’t see anyone wanting that because it is old technology and it can’t do what the newer mono-shocks can do. There is too little travel. It aint no good! Too little travel only for those that need more travel which is obviously not everyone. There are tons of KDX owners that fit this description. They don’t use what they have. “Tuned” is a term like “jetting” where you get that stupid look like “It’s brandy new, it is perfectly jetted or the suspension is perfect cuz it’s brand new.” WRONG! Most everyone has to re-jet. For $250 I got 03 KX250 forks, tuned perfectly by me, to handle the terrain that the stock KDX forks couldn’t handle. Now it is better in ALL situations. They are plusher at low speeds, sharp edge high speed and high speed whoops cuz they have 3 circuits in them to handle this. I can ride faster, longer, and have more fun SAFER. Yeah, they’re worth it in every way.
'04 220 w/'01 KX250 USD forks, '02 RM125 Showa shock, Rekluse EXP 3.0, LHRB & all RB'd
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Jeb
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Post by Jeb »

bradf - I know what you mean by the front forks, they do seem softer than the rear, and my riding style will necessitate a different setup.

I also know what you mean about gettin' a bike and spending a bunch of time getting things right 'cause I honestly think in retrospect that it was even harder then than it is now to get things right. when I raced mx in my teens in the early '80s we worked endlessly to dial things in - jetting, air filters, sprockets, silencers, tires, suspension - the whole shooting match. We didn't have nearly the kind of resources of today (information - the internet) nor did we have the aftermarket smorgasboard. Yep, making it "happen" today is really a whole lot easier.

Understand that one of the reasons I chose the KDX over a used mx bike was the stiff suspension on the mx bikes. My understanding was to get it right required a whole lot of $$ to get the suspension set up. But I'm learning as I go along and thus am interested in your setup.

Presumably the forks are used ($250). What year are your KX forks? What did you have to do to get 'em "perfect"?

Thanks!!
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bradf
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Post by bradf »

I got em through ebay. $131 + $21 shipping. Some here have switched to USD KX forks as far back as 94 I think. They like em too. I wanted the larger size and held out for 3 months till the '03s came up for bid. I did my own shim stacks with help from MX-Tech. I swapped a bit of info I knew for a bit of info they knew and it was good. Mine were bladder forks and I eliminated the bladder altogether and modified the mid-valve circuit as well as the restrictive barrier and different spring rate. All that to say this, These forks are so good and so capable that now I am riding much faster and harder and I am more comfortable doing it. But I don't do jumps. But I love whoops. Now I am having a Showa shock off an '02 RM125 modified by Jeremy Wilkey at MX-Tech to replace my KDX KYB shock. Why? Cuz the KYB can't handle what I need. The shock was fine with the old forks when I was going slower. I didn't know what fade was then but I do now! I also know what it's like to dial in full compression and still blow through the stroke after a few runs over the whoops. The Showa will easily handle that little task as that is what they were made for.

A side note: I got my KDX when I lived in NW Washington and rode very tight narrow trails. The KDX was perfect there. Now I live in south GA and ride in the Tallahassee area and the KDX is out of it's designed element. If I were to do it again, living here, I would have gotten a KX or YZ or CR.
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Post by thebleakness »

I have decided i need better forks. Today when i was riding (Upper Moto for you arizonans) there were times when i had the forks compressed all the way trying to ride over some rocks/boulders and it would stop me from rolling over. I think had i had stiffer forks (mine have been stiffened already) it would have been easier to hop these.
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