What rear shock spring rate?

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robkdx
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What rear shock spring rate?

Post by robkdx »

Im 225lb. What rear spring rate do I use? Most say 5.2kg but the 5.0kg on the bike is very very soft. The Racetech site says I need 5.8kg.

This has been really highlighted by me fitting the KX125 forks which are much firmer than the back.

Also can I just undo the shock and pull it out the rh side of the frame?

Im sending the shock off for a rebuild as it is leaking a little.

My bike is an 2006 H series.
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Re: What rear shock spring rate?

Post by MikeNZ »

Nope they would be wrong Im 215ib and 5.8 works great. you can get cheap used 5.8 spring from bike wrecker as this spring comes standard on klx 300. Both bikes use KYB 44mm rear shock but kdx has 5.0 and klx 5.8 (the one you want). cant imagine 5.2 would be much of an upgrade for your weight. Racetech.com calculator suggests at least 5.8 for your weight. hope that helps.
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Re: What rear shock spring rate?

Post by robkdx »

Cool, thanks Mike. Confirms my thinking. And cool, I know which bike to try and track one down from!

Are you a Kiwi?

Doh, just clicked we spoke before. Out of interest, which wrecker did you go to for the spring?
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Re: What rear shock spring rate?

Post by MikeNZ »

was just a local palmerston north wrecker cant remember name paid $60. DOH didn't realise that you were Kiwi either. Where did you get your forks from? I have upgraded my front prings to .44 from memory they made a huge difference over the original .38's (scored a brand new set racetech's on trademe for $50). You will love the 5.8 rear. cheers mike T
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Re: What rear shock spring rate?

Post by MikeNZ »

by the way shock comes out underneath bike need to remove bottom tie rod front bolt and lower shock bolt then remove tie rod, then undo top shock bolt and drop shock. To be honest I couldn't get my tie rod off and gave up in disgust the lower shock bolt was seized so took to mate who is motor cycle mechanic, he applied heat and much hitting and swearing still wouldnt budge so butchered it to get it out. Apparantly this is common with these. If you dont have manual can email relevant pages if you give me your email address cheers mike t.
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Re: What rear shock spring rate?

Post by robkdx »

Mines all been apart last year and regreased so i know it will come apart. Will try and Google the guy in Palmy.
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Re: What rear shock spring rate?

Post by robkdx »

So got a 5.8 spring. Pulled the shock and had it serviced. Had never been apart. When i pull the old spring off it had about 40mm of preload on it. Scary. New spring has about 14mm preload to give me static of 35mm and rider sag of 100mm. Bang on the money.

New KX forks have .42s which feel good also but a bit sticky as it has new seals and bushes. Will give a couple of good rides then do new oil in the forks.
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What rear shock spring rate?

Post by SS109 »

.42's are too light for your weight. I run .41's and I weigh about 170 with all my gear.
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What rear shock spring rate?

Post by Bitteeinit »

If I weigh 190lbs in riding gear, should I bother with any upgrades? From what I've heard, there are two options when it comes to KDX suspension upgrades:

1-KX forks (125cc-500cc). The best upgrade, but requires a decent amount of $$$ and modifications to work.

2-Switching springs (both front and rear). Given that the standard forks/springs are rated for 180, is it even worth it for me to switch the springs? I have the USD forks if it makes a difference (92). The whole setup feels saggy (front AND rear) but I might try to play around with the oil types to stiffen it up a bit.
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Re: What rear shock spring rate?

Post by 6 Riders »

What bike do you have? A 92 200 has standard forks, 93 & 94 have USDs. The Water Cooled 250 came with USDs all years (I believe). If you have 200 USD forks, the stock springs are for a 100# rider (.28 thru .31 where available stock). If you have a 250, I personally have no idea what the stock spring weight is, but KDXs are notorious for having to light of a fork spring. The rear spring will work just fine for your weight.....Just a side note, when stating weight, do not include w/gear, just your regular weight.
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What rear shock spring rate?

Post by SS109 »

Bitteeinit wrote:If I weigh 190lbs in riding gear, should I bother with any upgrades? From what I've heard, there are two options when it comes to KDX suspension upgrades:

1-KX forks (125cc-500cc). The best upgrade, but requires a decent amount of $$$ and modifications to work.

2-Switching springs (both front and rear). Given that the standard forks/springs are rated for 180, is it even worth it for me to switch the springs? I have the USD forks if it makes a difference (92). The whole setup feels saggy (front AND rear) but I might try to play around with the oil types to stiffen it up a bit.
Who ever told you that the stock fork springs were good for a 180 lb rider was smoking crack! Stock forks are good for someone around 135 lbs at best. The stock rear is good for about 180 lbs. Also, springs do wear out. No matter which way you go, get new springs for your weight. As for the stock forks, they are great for gnarly, slow speed, technical riding or leisurely paced trail riding. However, if you wick it up to race speeds, or like to blast fire roads, etc., the stock forks are down right scary and could get you really hurt. JMHO and YMMV.
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Re: What rear shock spring rate?

Post by Bitteeinit »

135lbs?!? ****! According to the frame number, I have a 1992 SR with USD. I used to think it was a 94, but the frame number indicates it was a 92 (and world market SR's had the USD as early as 92). This info was given to me on this site.

So what kind of springs should I get? Any ebay links? Any specific brands? Do USD have a different length than standard forks?

Also, is it possible to use spring from a different type bike? I remember reading about XR springs being used...
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Re: What rear shock spring rate?

Post by 6 Riders »

Look for .42 springs. Maybe .44, I'm 160 (w/o) gear and use .41 springs, I could go a bit higher, but I can use oil to stiffen them up a bit also.
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Re: What rear shock spring rate?

Post by KDXGarage »

Biteeinit, could you please update your profile to include your country?
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Re: What rear shock spring rate?

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6 Riders wrote:Look for .42 springs. Maybe .44, I'm 160 (w/o) gear and use .41 springs, I could go a bit higher, but I can use oil to stiffen them up a bit also.
Thanks. Do the USD forks and standard forks use identical springs size and length-wise? Are there any cheap alternatives to racetech springs? Meaning fitting XRL 250 springs, Suzuki Djebel or something else? I'll definitely try XR as they're widely available here and I could try them on for free.

This is definately a good thread for USD forks:
http://www.kdxrider.net/forums/viewtopi ... 77&t=12198

Do the racetechs come as an easy fit, or do I need to get more preload (they're shorter?) or something. Just looking for the least complicated alternative... And as for the rear: I assume they're the same on ALL KDX models (89-2000+)? Or is there also a difference between pre 95 bikes and 95+? What would be recommended for a 190lbs rider?

And out of curiosity, if a 190lbs rider needs .42 or .44, what are the stock springs rated at?

EDIT: Racetech website says:
FRONT FORK SPRINGS
Recommended Fork Spring Rate: 0.438 kg/mm (use closest available)
Stock Fork Spring Rate: 0.296 kg/mm(stock)
Jason wrote:Biteeinit, could you please update your profile to include your country?
Done.
Last edited by Bitteeinit on 08:09 pm Aug 13 2014, edited 1 time in total.
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Re: What rear shock spring rate?

Post by 6 Riders »

My springs are from Cannon Racecraft. I actually bought them through a suspension GURU that "just happened" to have them in his "attic".
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Re: What rear shock spring rate?

Post by KDXGarage »

Thanks for updating your location profile. I keep meaning to type up some thoughtful new thread to encourage everyone to post his country, as some models (like yours and the forks) are different and mot people on here are in the USA and just think about the USA bikes and what characteristics the USA bikes had. I had no clue the G?? model had USD forks back in 1992 until I looked up the frame number for you.

The Honda XR fork springs WILL NOT work in "what we in the USA call 1993 - 1994 USD forks". I used to have a paying hobby suspension service and test fit various springs in the 1993 - 1994 USA USD forks. Race Tech 3647 model is THE BEST choice of all the springs I tried / used. Race Tech and FRP Offroad are the ONLY aftermarket springs that I found to work.

The preload length was about right, as far as I remember. Current preload amounts are a little less than a few years back (4mm instead of 10mm on the Race Tech site), but they are still the best option.

USA Honda XR250 springs were too short, as best I remember. Check spring length before taking a chance.

In the USA, the 1989 - 1994 springs are .30Kg/mm rate. Basically, ball point pen springs.

On the rear spring, 1989+ sprigs are all interchangeable. Drive over to the house, and I will give you one. :mrgreen: I know. :kick:

What is the actual weight of your bike? I am only used to spring rates on the 233 pound E models. If your bike has the steel tank, blinkers, speedometer, etc., (can't remember if they were still on or not), then it may be a touch heavier.

In the USA, the stock 1989 - 1994 "E" model KDX200 shock spring is a 4.6 Kg/mm rate. Assuming your swingarm, linkage and such does not cause a different need, then a 4.8 rate may be what you need.

*******and Cannon Racecraft***************** (just saw 6riders post)
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Re: What rear shock spring rate?

Post by KDXGarage »

Eibach Honda XR250R springs are 432 mm. 990 series
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What rear shock spring rate?

Post by robkdx »

SS109 wrote:.42's are too light for your weight. I run .41's and I weigh about 170 with all my gear.
Racetech site tell me i need .416 fork and 5.827. Im 100 kg. Rear spring has come up what I think is perfect for sag. i will see what the fork is like after a couple of rides once run in.

Out of interest it shows the stock fork springs being .36
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What rear shock spring rate?

Post by robkdx »

Bitteeinit wrote:If I weigh 190lbs in riding gear, should I bother with any upgrades? From what I've heard, there are two options when it comes to KDX suspension upgrades:

1-KX forks (125cc-500cc). The best upgrade, but requires a decent amount of $$$ and modifications to work.

2-Switching springs (both front and rear). Given that the standard forks/springs are rated for 180, is it even worth it for me to switch the springs? I have the USD forks if it makes a difference (92). The whole setup feels saggy (front AND rear) but I might try to play around with the oil types to stiffen it up a bit.
Do a proper sag check. That will tell you the answer.

I bought a kx125 with a blown motor. Kept the forks and sold the rest. Just sold the KDX forks. All up made about $10. Win. :supz:
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