KX to KDX Rear Suspension Swap

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KDX220PHIL
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KX to KDX Rear Suspension Swap

Post by KDX220PHIL »

Anybody try converting the rear suspension on a KDX with a KX?
Why can't this be done?
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Indawoods
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Post by Indawoods »

Nope...Shock is an inch longer... :grin:
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Post by KDX220PHIL »

What about replacing the swingarm too?
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Post by KDX220PHIL »

Or is the shock mount that is the issue?
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Post by Indawoods »

I think CMOT has done this... I'd PM him to ask what was involved.
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Post by skipro3 »

I tried. The longer shock causes the swingarm to extend too far down and it hits the frame. Also the angle of the chain sprockets is all wrong. I think that if the KX lower linkage was changed too, then it might work. A complete swingarm change out too might do the trick. But seriously, I've got both, a KDX and a KX and the KDX rear suspension is every bit as good as the KX on the trails. I would recommend that you not waste the time. Yes, some KX rear shocks have high speed dampening control, but I would not think you could tell the difference.
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Post by KDX220PHIL »

How about for jumping 7ft. + of air? Do you find the KDX rear suspension adequate? How would a revalved KX Shock compare to a revalved KDX?
I think our terrains may be different but I drive in very little rocky terrain, mainly highspeed woods and open fields, sand pits, lots of hard packed, whoops, and some sand and mud. I don't like to crawl over obstacles like whoops, I like to hit them with speed (except logs, already had an incident there). Would the terrain I drive in change the requiremt of the shock in comparison to rocky terrain? One more thing, jumping the bike is something I never plan giving up, I love jumping as much as I do woods riding.
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Post by kdxquebec »

Jonhkdx220 on this forum have a kx frontend an a rear kx shock on his 220.

I will link him this tread and he will reply!

phil...
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Post by layoutd »

would it not be easier to put a 200 or 220 motor in a KX frame?
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Post by KDX220PHIL »

Sure it would be, but what's the fun in that? If i had a KX frame I would be putting a KX motor in it. :grin:
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Post by KDXer »

I am usually known for not letting the truth get in the way of a good story but this next one is gospel, Scout's honour.

I was hitting a 40' t/top on a International class MX track when I first got my KDX. After jumping it all day doing simple little tricks I decided to try preloading / seat bouncing to get extra height. Big mistake.............. Well to cut a long story short we ended up approx measuring 60+ foot. So what you say ?!? Well that was stock standard KDX suspension all round. I'd say the KDX shock with revalving would be more than suffice. Here's a dodgy pic to illustrate the distance I jumped. And yes it did hurt but I didn't crash.
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Post by KDX220PHIL »

Excellent!
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Post by KDXGarage »

Just to be sure, are you asking if anyone has put a KX shock on ANY KDX, or does "a KDX" mean a KDX of the same model family as yours??

GOOD JOB!! Indawoods to remember that CMOT has a KX shock (and forks) on his KDX200 E model. He said he has 1989 KX forks and shock on it.

If a shock is valved to work well for riding rocks, logs, ruts, roots, etc., then it won't work well for the MX track. Think dual-purpose bike. Good at both, but not fine tuned specifically for either. It would be a compromise. The same goes for a KX shock. If it were fine tuned for a high speed MX track, then it wouldn't work so great plonking along through rocks and logs, etc.
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Post by IdahoCharley »

If the main problem is just that the shaft on a KX shock is an inch longer then a good suspension shop should be able to shorten the shock. The problem then becomes (in my mind anyway) is that the valve stacks that will work with the shortened shock may not be well known. i.e. I would want the shop to commit to revalving it until I was a happy camper
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Post by KDXGarage »

Yeah, what he said.

Unfortunately, by the time one pays for getting a KX shock shortened and revalved and re-revalved a few times, the time and money may not be worth the trouble.

Great point on the revalve information perhaps not being too well known, as a shortened KX shock in a KX is a lot different than a shortened KX shock in a KDX with different:

swingarm length
linkage design
linkage mount location
shock mount location
the many differences in mounting locations of various parts
etc.
etc.
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Post by gwhII »

If you're wanting a hipo shock, another option would be a Works Performance shock, http://www.worksperformance.com/html/dirt.html. Look at the DB app guide. They list Duracross and Ultracross models for the H series. Haven't tried them before so I don't have any firsthand knowledge but I've seen some good reports on them. They will customize valving setup to what you want it to do.

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Post by johnkdx220 »

Anybody try converting the rear suspension on a KDX with a KX?
Why can't this be done?
For the record, it can be done even if the shock is 1 inch longer. I "temporarily" installed a KX 250 '01 shock while waiting fom the busted kdx shock to be revalved (unfortunatly the rebuilder-racer went to never never land and I'm stuck with the KX shock he lent me for 0$)

On the motocross track, the KX shock is absolutely great. Man, bring on those whoops and double jumps. Whoohooo. In the trails, it performs as well as the kdx shock only if I adjust the settings to the softest. My biggest problem is that the bike ends-up sitting taller.... this is not a good thing in technical trails if you are vertically handicaped like me.

Overall, I'd prefer having back my kdx shock revalved to my liking. For now, I enherited a KX shock and learnt to live with it.

No problem with clearances, frame hitting...
Oh, by the way, shims are necessary on the top mount (the KX shock mount is about 1/8 narrower).
KDX220 (RB'd, EFM Autoclutch, FMF Rev, KX front end... Crash proofed and crash tested tOO often !)
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Post by KDXer »

Hmmm, 1" higher in the rear could be easily balanced with KX forks. I would love an extra inch (my bike that is). Something for me to look into now... A KX shock..... Would the extra height all round throw the bikes geometry out, IE, steering, etc.
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Post by skipro3 »

John, that KX shock just bolted right up?? On my KDX, it would not fit. The lower part of the shock hit the swingarm when unweighted. Race sag, no, but in the air, it hit hard. Also the angle for the chain was very wrong. Any photos?
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Post by KDXGarage »

Hi, johnkdx220, if you have any photos, or can take some, I would like to see it as well.

Thank you.
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