i have an 09 klx 250s, i was wanting to beef up the suspension up a bit. i dont have the cash to go with racetech, and after being on the phone with devol suspensions when i had the money i was quickly turned away,why i dont know. so i was wondering if anyone knew of any rear or front springs that would fit on the klx 250 that may come off other bikes. possibly for the rear the whole shock assembly off a kx or kxf 250 or 450? any insight would be great as i do 90 percent off road, and trail riding so the beefed up suspension is a must!

 

You can replace the whole front fork assembly with forks from a kx250 which are much stiffer.

 

Ya, but one thing to remember is that the KX forks are only valved stiffer. The springs would need to be replaced just as they would in our cheapy KYB forks. In fact, they're valved for MX which is way stiffer than the enduro riding most of us do with our KLX 250s. Unfortunately, thet means really stiff to the point of uncomfortable in woods riding. The newer KYBs have enough adjustment built in to go from MX to enduro with nothing but clicker settings. Not so for the 95/96 43mm KX forks that are a straight drop in for out triples.

I've done the KX replacement forks twice - first in my KLX331 and then in the KDX.

I personally tried KTM RFS springs (43mm from 200-2002) in my klx forks. They are about 1.5" longer than our KLX springs and the automatic preload would have been disastrous for the plush feel over square edged trail trash. I abandoned the idea when I tried to compress the spring and reinstall the cap.

I'd still like to make that ebay rear spring work for $79. Haven't heard if it fits the shock without a different lower support though. IIRC our springs are tapered and take a smaller diameter lower support. Anyone know for sure?

 

As dj mentions, I think there's a lot of myth surrounding the apparent magic of just bolting up another set of forks to a KLX and being able to ride off into the set with everything perfect. I'm not saying you couldn't get lucky with some other fork in terms of the valving and springs being ideal for your use on a KLX, but think of the odds. It's more likely you'll need to valve it and respring it to achieve perfection. The compression spiking on our KLX fork is a valving issue, and it's so bad that I think there's probably some immediate relief when you throw on a KX fork...but...that ain't perfection. If I'm going to the trouble of putting another fork on my bike, I want just about every performance benefit I can get out of it. The KLX fork isn't junk, but the valving and spring rate are just wrong. That can be fixed.

jhoff, on that fork stiffness issue, I don't think the KX fork that is being swapped in most of these cases is any stiffer. They're both KYB USD forks, and they're both 43mm stanchions. The benefit is in the damping and having access to external rebound clickers. If you run 5wt fork oil as recommended, I don't find the rebound on the KLX fork to be a problem. It's the compression that's the real problem, and a revalve from Race Tech or Moto Pro fixes that big time.

dj also hits upon the problem with spring compatibility. You can't just go throwing different springs for different bikes at our KLX or most other bikes for that matter. It's not always just length at issue, especially for the shock. Spring taper, shock collars, and other issues can get complicated. If you really know what you're doing by studying spring dimensions and spring charts, you might find something from another bike that will fit. Some of us use the KLX300 shock and fork springs in our '06/'07 model 250S, but even those 300 springs are not exactly equal, and you either have to check for clearance issues or do some creative preload spacers. Obviously not rocket science but noticeably different even on two bike models that are close to being identical.

 

thanks guys for the advice, but yeah i dont too much mind the suspension on the klz it is plush but not built for the abuse, just trying really to keep it from bottoming out in the main concern, the front isnt so bad as the back is being that im on the back tire most the time, im about 180 pounds with gear on so i was thinking about just swapping out the stock 5.8 rear spring for maybe a 6.0 but would hate to get a 6.0 if possibly i should get a 6.2 or something, anyone do something like this with there bike?

 

I think most us would be surprised to see that you're happy with the front but disappointed in the rear, especially at 180 pounds, but that's your call. Have you tried preloading the rear shock spring a few mm's to help? Do you know how much your rear spring is preloaded at the moment from its fully extended length? I went to a 6.0 spring, but I weigh 190 without anything on, wear a huge hydration pack, and have a rear rack bag with tools/parts in it...and I ride somewhat aggressively, though not the Bubba Stewart category. You might think your bottomout is too soft a rear spring, and it could be. However, realize that too soft a preload will allow the shock to blow through its travel more quickly when you are running too soft a preload to start with. A little preload goes a long way on this shock.

 

I've always been of the belief that the preload only affects the sag and has absolutely no effect on the way the shock goes through it's travel.

 

And I would have been pretty much right there with you from my experience with past dirt bikes and high-end full suspension MTBs...until last week. When I got through with my recent Utah trip, I was firmly convinced that I needed a heavier spring on my KLX. I had 135mm of sag on my 6.0 spring with no preload. That's a ton when you consider it should be about 95mm. These springs usually have a max of about 20mm of usable preload. I underestimated the ratio of preload distance on the shock body to the actual influence on ride height. Yes, I should have spent more time with the stock spring, but I didn't think I'd get 40mm of ride height resulting from it.

So, I bought a Race Tech 6.4 spring and got down to business setting it up...like I should have done with the 6.0 more seriously. Well, after spending a whole day with the 6.4 and the 6.0, I realized that a mere 13mm of preload on the 6.0 brought the static sag with me on the bike to 95mm and the free sag with just the bike to 25mm...perfect. But...how would bottomout be affected? Well, when half the travel isn't already eaten up in sag, the spring has much better ability to compress and dispose of the energy during a compression stroke. I was totally in your line of thinking that bottomout would be bottomout and just be harsher if you had too much sag. I rode the bike today out on a trail, and the difference was night and day. I had very controlled ride height with a very progressive feel from the spring and damping. In G-outs the bike was extremely controlled without the bike going to the bottom.

I'm no engineer so I can't qualify my experience here scientifically, but I'll try to describe what may be going on. For one, the setup in the nature of the damping in the shock can play a part here when you consider that too much sag removes a significant amount of distance on the shock shaft that the shims and oil have to deal with compression. So, that puts you a bit in the hole right there. And with a spring already compressed to a less than optimum length, I think there may be a diminished amount of energy that it can deal with from that point to bottomout. Still, I'm thinking the shock position as it affects how much time and distance your damping has to react to a hit when nearly half of it is lost to sag may be the biggest factor. I may be all wet here as to my assessment, and I certainly welcome any other fellow experts...LOL!...cough, cough...to add their 2 cents. The good news...I got the Race Tech spring at shop cost, so my tequila budget wasn't totally busted.

 

All this talk about springs and bottoming out.........What changes have been made to the shim stacks in the shock?

Ride on
Brewster

 

I've been running the stock spring and shock and have been bottoming on g-outs lately
I'm 180 w/out gear with about 15 lbs on my rear rack and was looking to get another spring to start, but after reading TNC's post I am going to wind up the preload a bit and maybe dial a little more compression.