I would check with your local bike dealer. I've got them for an 03 KDX and a 02 Gas Gas. One brand is "Motion Pro - Pro Bleeders". This is the best $25 you will ever spend on your bike. You will say goodbye to replacing fork seals.
Is the ones you got the same as for a KX 250? Specifically is the thread a M5 x .8 on the KDX just like the KX? I even called Motion Pro and they don't know if they will cross-reference. Without me measuring my little bolt I thought i'd ask here first.
You may want to read this excerpt from a post by Jer [MX Tech] on a thread in his suspension forum. Just as in your shock, a bit of pressure is necessary to keep foaming to a minimum. ............................................................
"Well the fork uses pressure inside the overall to exerted force on the fluid inside the fork.. Now what happens at the top of the stroke? We get decreasing pressure in the rebound direction and that means that the fork tends to undefiled the fork at the top because with out significant internal pressure little more than cohesive forces actually fills the thing. (this problem is still relevant BTW more on this latter) With the circulating system we dump a significant amount of oil (rebound clicker value) out the top of the fork where it is emulsified further and thats also means more oil has to be refiled into the cartridge. This is one reason why I tell people not bleed air out of there open cartridge forks every ride.. By running a small internal pressure your helping your fork work better (more consistently), and that's a small price to pay ..." [He obviously doesn't proof read his posts but there's lots of good info to be had in his forum]
you should always bleed the forks with the wheel off the ground. That way you are not pressurizing the forks postively or negatively.
The reason we need to bleed the air from the forks is the change of temperature expands the air inside the forks. Thus you get a pressure that causes a noticeable difference in the compression dampening of the forks. Thus bleed the air off to eleviate this pressure.
You can buy kits that are handlebar mounted now. So when you take that double or tripple, just push the button!