KDXRIDER.NET

I'm changing my fork oil (finally...) and I have some questions that I couldn't find the answer to using the search function. I used fork+oil+height as my search query but the search function kept deleting fork and oil and I just keep getting ride height modification articles. Am I doing the search thing wrong?

So I'm in the middle of doing the shim stack modification and have seen different amounts of shims to delete. I'm going with taking 2 away from the stock 10, leaving 8 shims, is this the general consensus?

I went to Race Tech's page, put in my stats and they gave me 140mm as the fork oil height. I've seen people recommend 100mm and all heights in between. I'm a 6'2" 190lb (no gear) 64 year old fairly fast New England trail rider, so rocks, mud, mountains, tight and twisty. All stock forks on a 2003 KDX220 with the shim stack mod when I'm through and plan on running 5 weight Maxima. Is the 140mm a good height or should I do something different?

On a side note, I made a fork cartridge holder as described on here using 1/2" x 30" black iron pipe and a brass fitting (Home Depot sku 894907). I cranked the heck out of the fitting onto the pipe and cut off the threads with a sawzall and for $17 worth of parts and a half hour of my time I had a perfectly good fork cartridge holder. Thanks for the tip guys!

Thanks in advance for any help with the above!

So in gear, you are 205 to 210, correct? It is going to be mushy ride with stock springs.

I would go with 8 shims and 100 mm. Be sure to read up on fork spring rates. 0.35 stock rate is a way out of date method. The old way often was heavy damping and soft springs. Nobody does that in the modern world. Look at rates of modern bikes. Even a lighter YZ250X comes with 0.44. That is for a 175 pound rider in gear.

HAHAHAHA! Thanks KDXGarage! I actually have a printout of your exploded view of a disassembled fork sitting on my workbench for reference! So thanks for that as well!

I'm planning on heavier springs in the near future. Racetech says that I should be running 40kg springs. The closest they sell is a 42kg spring. Does this sound about right or do I need to go heavier? I ride with full gear plus a Camelback. I don't know the exact weight as I don't have a scale but hefting my gear bag and boots it seems remarkably heavy, maybe 40lbs worth??? So I'm maybe 230lbs fully geared up??? Maybe I'll freak my friend's wife out and go stand on her scale tomorrow with my dirty dusty self and get an exact weight....

As always, thanks again for your help!

That's cool that you have a printout of the disassembled fork.

The oil height difference is going to mainly control bottoming. The air pressure in the fork will ramp us as the fork compresses in the last third of travel. It won't make much difference in the bottom half of travel.

The springs are to keep the weight of the rider and bike up at a certain height. As you are 6' 2", you don't need it to sag and help you get your feet on the ground. You need stiffer fork springs and a stiffer shock spring.

Grab all your gear and get on the scale. No need to put it all on. I would assume 20 pounds minimum with a filled water backpack. Don't forget any tools or spare parts. Any mud or dust will add weight as well.

Without the correct rate springs, one cannot easily say to add oil to control bottoming. You could start with a low level, then add to it if bottoming is a problem, but the main problem is going to be the springs.

Get the forks and shock in proper condition with seals and nitrogen correct pressure in the shock, then worry about springs, then valving.

You need at least a 5.2, but maybe a 5.4 in the rear to get the sag height numbers correct. With the correct springs, it will sit up a touch higher, but it won't hurt a 6-2 guy. :-)

I don't think 0.42 is stiff enough. Will it be a ton better than stock, OH YES! Will it be as good as it is supposed to be, no.