KDXRIDER.NET

I'm trying to buy new fork springs. I'm 150 pound w/o gear.
I'm confused. Racetech recommends much stiffer springs than Fredette.
So which rate one should I buy?

Racetech ===== .446 kg/mm fork spring (for 150 lb rider)
Fredette ===== .38 kg/mm fork spring (for riders 140-190lbs)


[Update]: I got a pair of XR400 springs. See my posts below.

I am in the same situation and also noticed the big discrepancy. Well not exactly, i weigh 165 without gear and bought the bike with .44 race tech springs.
The forks seem very harsh and after the last cross country/woods race i vowed to get the forks sorted and also found it confusing with spring rates.
I have the forks off ready to take in to a recommended susp guru and had hoped to give him some good guidelines but need help.

Racetech tends to recommend higher spring rates than most woods guys would like.

The XR400 springs are a good option for the stock forks.

I would say around .40 for the 150 pound guy and .42 for the 165 pound guy, assuming 15 pounds of gear.

If you have tools, spare parts, larger fuel tank, water backpack, etc., it can add up.

I'd say .44 is a little too stiff for the latter poster.

Search for threads on removing a couple of shims from the base valve of the forks. That will soften up the damping, AFTER the correct springs are installed.

.44 is ridiculous for that weight and hare scramble type racing. I'm 150-155 and I used .38 in mine. I have .4 in my MX bike and that's perfect for me.

OEM

OEM

I to noticed my son's 98 kdx 220 forks were harsh on trail junk. They also rebound to fast. The front end does not want to say settled coming into turns. Causing the rider to do more work planting the bike into turns. I do my own suspension work. The bike I ride most is my 05 cr 250. I have revalved the forks to work great on the south eastern trails I ride. As for the kdx. The changes I made were removing 3 shins from the comp stack, to help the flow more oil on high speed impacts. Then installed them in the rebound stack (which is on the end of the cartridge rod that screws up into the) to keep the forks from rebounding to quickly. Rebound speed in forks and shock are key to a balanced well turning bike.
I am very happy with the forks now. As for my, son commented how much better the forks felt. Said he can go faster with more control and how the forks are more plush.

Son is 135 pounds without gear.
Forks .35 springs
Skoch. 4.7 shock. Revalved. The details of which are posted in my thread. 98 kdx shock revavle
Hope this helps someone drive into there suspension and make it better.
Steve

terminator, try 5mm. You will have to measure and cut a spacer to the proper length.

I measured the preload on the old spring, and it was almost 25mm.

By the way, there's only about 2mm of free space between spring and top cap. So I need an 7mm spacer. I think it's kind'a difficult to cut such a short spacer by hand accurately. Maybe I need to buy a table saw?

You need a miter saw. Not a table saw.

Have you got a bench grinder?

Ah, to heck with it. Just get some washers and stack in there. Some new fork spring kits came with 3mm washers. Just head to your local hardware store and try to find some washers to put in there.

Be sure that when you have the fork fully extended, it all stacks up to where the bottom edge of the cap (the part that hits the top of the fork tube upon tightening) is 5mm higher than the top of the fork tube.

The washers are a lot wuicker than cutting a tube when it comes to taking up a small amount of space.

I used 3/4" schd 40 PVC glue couplings and cut them down.

I used a table saw, which worked fine, but you need someone else in the garage to try to catch 'em when they go zipping off into the corner.......

I cut the 7mm metal spacer freehand using a Dremel. And I am surprised it turned out pretty good.
This spacer should give me 5mm of preload as recommended by Jason.

After bouncing around in a parking lot, I don't feel much difference between this XR400 fork spring and the stock fork spring.

• What fork oil should I use with the XR400 spring? It's got O-reilly ATF Type F oil in there right now.
• The rear shock spring is currently stock. Does it work well with the XR400 spring? I already have a softer shock, but haven't install it yet.

The XR fork spring (either weight) is a good match to the OEM rear shock spring.

I liked 7.5 wght fork oil. I mixed 5 and 10 wght 50/50.

Fortunately, you did not change out the springs to ride in the parking lot. :-) Hit the trail, then report back.

I use 5 weight fork oil.

150 without gear? Check your sag. You might need a 4.9 or 4.8 spring.

terminatr wrote:
After bouncing around in a parking lot, I don't feel much difference between this XR400 fork spring and the stock fork spring.

It's got O-reilly ATF Type F oil in there right now.

That's probably why.

You need something thinner in there. One of the quality 5W oils is a good start.

If you can, try this:

It works well for me.


http://www.montgomeryvillecc.com/Kayaba ... Id=8145703