Marzocchi magnum forks on KDX

That's definitely an odd combination. Are the 'zokes 45mm or 50mm (you'll need to measure the diameter of the fork tube)? Has the entire front-end been changed? It probably has a Brembo front brake and master cylinder which is definitely an upgrade from the stock KDX front brakes.

Certain KTM's, Husky's and GG's (like my '98 EC) came stock with 'zokes. I can't tell you if it's better or worse than the stock KDX (KYB, I think???) forks. Like any other bike you'll need to have the forks sprung for your weight. Changes in the oil weight and height can vary performance some what. The clickers control only a small part of the damping. There are quite a few mods that can be done to the 'zokes to improve performance.

The 'zokes do have some unusual traits. The left leg controls compression and the right leg controls rebound. The sliders are extremely soft therefore frequent oil changes are recommended. The aluminum will wear rapidly, contaminate the fork oil, increase wear on the bushings and eventually the seals will leak. I have seen numerous 'zokes (both 45's and 50's) that just pump oil. To cure this condition I had MX-Tech hard anodize my sliders in March of '01. I did change the oil last winter, but still have the same bushings and seals. My forks have not leaked one drop of oil.

Hey pheanix, if you're still around, I'd like some more details on your Marzocchi front end. Does it use KDX triple clamps? What wheel/axle/spacers?

Ah, thanks. Do you know what was done with the steering stem and bearings?

(If you haven't guessed, I've got a spare set of 45mm 'zokes w/ triple clamps w/ stem.)

I think the 45 zokes call for 7.5 wt fork oil. i don't remember the oil height.

I have heard of odd swapps like this before, someone has to know the details and how much it would cost...

The biggest cost factor in these endeavors is what you pay for the entire front end. Before choosing to go this method a couple of things need to be considered.
1. It is best to use the steering stem of the kdx so it fits into the head bearings correctly.
2. Is the stem smaller diameter than the lower and upper holes in the clamps. If so, all u need is some material to shim or surround the stem so it fits into the clamps, if it is too big than we are talking about getting rid of material from the clamp. I would not want to go through that trouble.
3. What is the original distance between clamps from the kdx to your retrofitted front end. I don't think this is too big a problem but some forks may not allow the clamps to sit farther apart than intended due to fork's outside curve. It seems like about 15mm is acceptable because that is about the distance you can raise the forks in the clamps to change the affect of turning.

Before I purchased a entire front end from a KX250 96 and put on my 96 kdx I was in mystery about this too. I had a set of 91 yz 250 forks and sold them with my old yz. I should have looked into this more because even an older fork like that was better than the spindly forks on kdx's. Don't be afraid to disassemble your front end so you to can figure out what is acceptable.