01 KX250 Fork Conversion (Revalve and Oil Levels)

Questions and comments about converting to beefier forks..
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Tigerzak
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01 KX250 Fork Conversion (Revalve and Oil Levels)

Post by Tigerzak »

Was wondering if someone here had the write-up that Bradf (with pictures) did on the 01kx fork revalve (said he made it back in 07).

I'm around 230-235 with all my gear and I'm looking at redoing the valving on the forks I've gotten. I've got the stock KX springs still in it and will eventually change for my weight but I would like to get them on the bike first. So far from reading on here it looks like I'm doing the following...

Remove the bladder and the bladder hardware

Base valve:
Remove all but 5 of the 24 shims
Cut 5 deep grooves (more than halfway into the restrictive barrier (RB))

Cartridge assembly:
No change (Could possibly remove the 22 shim for the very rocky stuff though I'm not sure how this affects the rest of the stack)

I have not found that much on the oil (5w) level. Guessing I'd want to run somewhere between 100-120mm, leaning more towards the 120mm.

Any help would be greatly appreciated! As mentioned Bradf had a write-up with pics on his entire tear down and changes. If anyone has that that could email it to me that'd be awesome!
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Re: 01 KX250 Fork Conversion (Revalve and Oil Levels)

Post by Slick_Nick »

At your weight, you are going to be too heavy for those stock springs, even for off-road riding. I wouldn’t bother with a revolve until you get the proper springs in there, or you’re going to end up doing it twice. You could end up trying to tune out harshness that is brought on by the forks being under sprung, and riding way too deep in the stroke.
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Tigerzak
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Re: 01 KX250 Fork Conversion (Revalve and Oil Levels)

Post by Tigerzak »

Thanks for the response Nick, Racetech recommends the following...

FRONT FORK SPRINGS
Recommended Front Spring Rate: 0.45 kg/mm (Use closest available)
Stock Front Spring Rate: 0.43 kg/mm (stock)

Is .02kg/mm that big of a difference? that I shouldnt even worry about revalve?
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Re: 01 KX250 Fork Conversion (Revalve and Oil Levels)

Post by Slick_Nick »

Yes, 0.02kg/mm is .2kg/cm which is 2 kg/dcm or about 4.4lbs per 3 inches of spring compression (napkin math) on a linear rate spring. You will definitely notice a difference.

I would install the proper springs and then ride it first, seeing how far you can go with the clickers. Remember that the rate recommended by race tech is for the KX250, which you don’t have. It’s about 20lbs lighter than your KDX, and the suspension rate recommended is quite soft for that bike. I’d even go up two steps on the springs to a 0.47.
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Re: 01 KX250 Fork Conversion (Revalve and Oil Levels)

Post by KDXGarage »

Look on thumpertalk.com in the suspension subforum for a mention of disabling baldders. On those, you can jut remove the restrictive barrier. If you want to remove the whole bladder system, then the oil quantity will be different as they take up some of the space.

You being 235 on a 250 pound gassed up bike is going to need more than .43. Don't look at the KX when going by fork spring rate. Choose the motorcycle, not the forks. You are looking at a several pounds lighter bike. When the KDX is used, it will require heavier springs.

Unless you are following the grandkids around the suburban backyard, 0.43 ain't the right ones. At least they won't be 0.35 like stock 1995 + KDX forks.
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Re: 01 KX250 Fork Conversion (Revalve and Oil Levels)

Post by SoCal Headgrinder »

Ride it before you make any changes! This way you have a base line and can also see if there are any other issues like misalignment or binding. I made the huge mistake of doing the fork swap, revalve, respring, lower the forks internally one inch, revalve and respring the rear shock and damatically changed handle bar set up all in one shot. And when I finally got it together and it didn't work right there were so many variables to work through. It was a long frustrating process which I am finally (but only 90% of the way to correct set up) having fun riding the bike again. Don't make my mistake!
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