Man...I'm downright impressed with the results from my Race Tech Gold Valve rear shock mod on my '06 KLX250. I've changed oil in a couple of my XR250R Showa shocks in the past but have never torn into the shim, seal head, and piston components on any of my motorcycle shocks. I got this KLX last summer, and it was clear fairly quickly that the rear shock had a compression spike in it on fast, choppy hits...or anywhere where fast shaft speeds were encountered. It was pretty bad, but I hadn't had time to dig into trying to eliminate it.

I called a couple of shock rebuild/mod outfits, and they all confirmed that the stock piston head in that KYB shock will not flow enough oil fast enough on high speed hits...apparently when you get to the "blowoff" stage of a certain kind of impact. The prices on shock rebuilds with mods was pretty high, so I looked into one of the Race Tech kits for the KLX300. They don't specifically have one for the '06/'07 KLX250, but everything I could find indicated that they were basically the same shock...along with the KDX200/220 and maybe some others. At least the Gold Valve kit for the KLX300 should work fine in the 250 shock, and it appears that it did.

I also replaced the whole seal head unit along with going to an EIbach 6.0 spring to replace the stock 5.8 spring. All spring calcualtions showed the 5.8 to be right for me, but my stock spring is too soft, and one must consider that the calculations I could find were for the 300 not the 250. The 250 is heavier, I wear lots of gear, carry a heavily loaded, large hydration pack, and carry some gear in a rack bag, front fender bag, and number plate bag for long dual sport outings in Colorado, Utah, and other locales. I easily bottomed the 5.8 spring when outfitted for long rides. The Eibach spring was about 15mm taller, and this concerned me at first, but the spring clears the airbox and other spots with no issue under full compression.

I used some Silkolene Pro RSF 5wt shock fluid for the shock. The shock shaft and inner bores of the main shock body and piggyback were in pristene condition...no marks, discoloration, or anything.

Here's why I went with the Race Tech kit. I'm not suspension ignorant, but neither have I gone whole hog on a rear shock internals mod. I've read many of the recommendations about just selecting the right shims and such and doing the job from scratch. My first issue for me would be which shims for which conditions. I'll be honest and admit that I don't have enough background here to just jump into that pool with any confidence. Another issue was the point of the stock piston/valve being a poor match for this bike and shock. I know there are shims available, but how would one go about finding and selecting the right piston? The Race Tech package provided all the valving components and an excellent video with very good written instructions. Frankly, it wasn't that hard at all, and the video gave some outstanding insight to rebuilds and tuning in general that was worth it all.

How did it work? I've finally gotten a couple of rides on the bike after the mod, and it is dramatically different. The harsh compression spike on square-edge obstacles at speed is gone. And there's an ability to stay on the gas harder and longer in really rough sections that I hadn't really noticed with the original shock setup. That part was a very pleasant surprise. These are the two most notable improvements. I'll probably pick up on more subtle advantages as I get time on this setup, but I'm very satisfied with the results right now.

I now have a Race Tech Gold Valve kit for the fork as well as a set of .44 RT springs. The fork wasn't as bad as the rear shock, but I'm looking forward to installing the fork kit and springs to see how that works out.

 

great to hear dude. i want to get valves done on both sides at some point, but money kills most dreams.

 

Thanks for the write up. What did the kits set you back? And id you have to buy any special tools? I really loved what RaceTech did for my Bandit, and have been thinking about this for the KLX.

 

I have gold valves in the shock as well. I scored a brand new set on ebay for like $75.

 

If the forks on the 250 are as bad as the ones on the 300, you'll notice a BIG difference, especially with your riding weight.

Ride on
Brewster

 

Yeah, there's a spike in the fork's compression too, but I guess too light a spring and the spike in the rear shock just made a very aggravating condition.

 

Sacrificial Anode, the Gold Valve setup usually retails for about $150-$170. That's about what I was quoted from two different suspension services for the parts in their "high tech" revalve and reshim setup. I'm not saying that they're using Gold Valve setups or such, but the money was close enough for me to try it myself, and it's been worth it from what I can tell. You see many of the suspension services advertising $150-$200 rebuilds, but by the time I added a spring, new seal head, new piston, and complete revalve, the price was generally always around $400 or more when everything was tallied up. I worked at a local shop for about 15 years as a mechanic, and they still treat me well. I was able to do the whole job for just over $200.

 

A nice write up and review. Congrats on the progress.

 

Thanks for the write up and the inspiration! I never knew this shock could be modified. I had thought the only way to improve the rear suspension was to replace the entire shock with an aftermarket one. How hard is it to open up the body of the shock?

 

Heavy, the disassembly and reassembly of the shock is really quite easy. The Kaw shop manual will walk anyone through quite well. Just servicing the oil can almost be described as easy. The shop manual doesn't go into disassembly of the piston/shim stack. The steps in the mod that were hardest was grinding off the end of the shock shaft where the shim stack/piston retaining nut was involved. The factories "peen" over or mushroom the end of the shaft to insure that the nut won't come loose. This wasn't particularly hard to do on a KYB, but it's a little nerve racking holding the end of an expensive piece of your bike to a grinder...LOL! Race Tech sends a new retaining nut and it is red loctited to the shaft when assembled.

This job required no special tools to speak of...torque wrench and a decent vernier caliper for measuring shims. A $15 Harbor Freight digital caliper was more than adequate...I think I got mine on sale for about $9. The Race Tech vid and text they send are extremely comprehensive, so you're not staggering around in the dark. I expected more drama in doing this mod, but it just wasn't the case. From looking at the vid that came with my Gold Valve fork kit, I think the fork will be more work but still quite doable by most home mechanics.

Every decent motorcycle shop has a nitrogen bottle to finish the pressurization step which is easy and cheap. When getting suspension parts for our pre-'09 250's, it appears that most components for the 300 will interchange with no issue. I am pretty sure that the Gold Valve, seal head, and other repair/mod parts for the shock are the same. Changing the internal travel on the '09/'10 models probably didn't affect the parts selection for piston, valving, seal head, etc., but I won't claim to know that for sure. From Race Tech's Gold Valve listing, I think they show the same parts kit for '09/'10 250's as the 300...or most of the KDX series...and some KX's. They may give a slightly different valve stack recommendation, but that comes with your kit and is not something that you have to wrestle with. Granted, I'm using a valve stack recommendation for a 300, as they show no listing whatsoever for the '06/'07 250, but I don't think this part is rocket science. The two bikes are so much more alike than different. Since travel is identical between the 300 and '06/'07 250, I'd use the shim stack specs for the 300 rather than the '09/'10 250. That's not to say the later 250's don't use the same recommendation from Race Tech, however.

The bottom line is that my '06 is extremely improved with the Gold Valve and shim stack for a 300, so I'm plenty happy with the results over what it was.