KDXRIDER.NET

For all of you that have done fork conversions, when you go to calculate the needed spring rate for the forks, do you plug in a KDX to get the right rate, or do you plug in your donor bike? I've got some KX 250 forks that I am going to put on to my KDX. If I got to Race Tech and use their calculator I get different suggested spring rates if I plug in a KX 250 vs a KDX 200. Just curious how everyone else handles this situation.

Im going to base it on the KX for my conversion as the KDX has shorter travel so the rate will be different.

Lucky for me, KX125 stock springs were right on. If I was trying to pick a rate though, my perspective would be different. I don't think travel has anything to do with the spring rate. Spring force is proportional to travel, but rate is independent of it. If you're going to trail ride, it makes sense to me to use the KDX rate because trail riding is the intended purpose and the springs are being used in the KDX, which doesn't weigh the same as the KX. Just my 2 cents.

I suggest one always go with the bike the forks are being put on.

Ride height is adjusted by spring rate. Getting the proper sag levels front and rear is important to handling.

After the correct springs are installed, it may change how the forks and shock should be valved. For example, the 1995+ KDX forks and the two shim mod works for those who have installed fairly stiffer springs.

turtle wrote: If you're going to trail ride, it makes sense to me to use the KDX rate because trail riding is the intended purpose and the springs are being used in the KDX, which doesn't weigh the same as the KX. Just my 2 cents.

I thought about that, but on the Race Tech calculator I put that I was trail/enduro riding, and all the other appropriate factors. I found a set of springs on Ebay that perfectly matched what the calculator said, but I'm really afraid they will be too stiff. I'll try them out, and if they are too stiff it won't be a big deal to swap them out. Hopefully I could get my money back out of them selling them off.

Valving....that is a whole different ball game. It will have to wait for some more cash flow to come in.

Where are you located?

If you are trail riding with KX forks, then yes, you will need a revalve.

Jason wrote:Where are you located?

If you are trail riding with KX forks, then yes, you will need a revalve.

Middle Tennessee. I rode my YZ250F for about a year with just a re-spring and did okay on it. I think I'll be ok with the KX forks as long as the springs I bought aren't too stiff. I do like to jump some, so a little stiff isn't too bad. We have a good mix of riding terrain in my area, from tight single track, to more open stuff, hills, logs, rocks, muddy ruts...pretty much anything but desert.