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I popped my forks open to check if the springs are stock or aftermarket, as well as clean/refill the oil.

They are actually 42kg springs. I'm 190 with my gear on and ride tight woods. I'm reading that 42s are good for a 200-250 lb rider. I'd rather save some cash and not replace because they are *so* close to my weight. If I drop the oil ~5mm would that soften them up just a bit and be a good starting point for dialing them in on the trails?

Also, is there a chance the springs may be "sagged out" or wore out and is this something I can check by maybe measuring them uncompressed?

Check your fork sag numbers. I am thinking you should be OK. .42 is NOT for a 200 - 250 pound rider.

Thanks for the reply.


I was going by FRP numbers I found here:

http://www.frpoffroad.com/aboutus.htm#aboutus

Maybe it's their spring specific numbers?

.42 should be about the right range for your riding weight, may even lean more towards .44 if you ride hard. As noted, set sag then ride and adjust. You can play with the shim stack some as well. What weight oil are you planning on running? if 5wt consider running 2.5/3wt. then play with heights. Oil is cheap, and easier to mess with than tearing into the valves.

Just for comparison, I weigh about 180 with gear and have Race Tech .44 springs. I also removed half the shims from the compression stack and use Mobil 1 ATF 130 mm from the top of the forks. My forks are definitely not too stiff in the tight stuff, but work pretty well at faster speeds too. The .44 springs are a huge improvement over stock, for me.

I'm planning on running 5wt. It was riding fine, I just had it in the back of my head that I had no idea what springs, oil level and weight were in my forks. Now that I know all of those, I'm going put fresh oil (5wt) and fill it to stock levels. I'll start hitting a good trail and tweak from there. Thanks for putting my mind at ease with the 42s.

Oil weight affects rebound more than anything else so don't change it thinking it can substitute for correct spring rate.
To have stiffer front end just make your own air valve caps and pump in some pressure. To make suspension softer just make sure the caps are vented. That relieves air pressure that happens as the space is compressed.

They should be about right for you im 220 and have .44 this was the best money i ever spent they are 100 times better than the stock springs. Stick with your .42's dont think changing springs is your answer. If you feel the need play with oil wt etc, otherwise just ride and enjoy.

Also 190 lbs w/ gear. On my last KDX I went with 0.40 kg/mm fork springs. If I could do it over again I'd go another rate stiffer.

In other words, another vote for "stick with what you have now!"






Just checked Race Tech's site (as MX Tech gives a big "?????" for the KDX).
180 lb C rider w/o gear they recommend 0.425 kg/mm fork springs.
180 lb B rider w/o gear they recommend 0.436 kg/mm fork springs.