I have been finding some interresting things about the "hot setup" of these forks. The KXF250 are the same as my red 450. The KX450 uses dual chamber Kayabas. For those who are not familiar with dual chamber forks, essentiall there is a self contained chamber inside the forks that is about the size of and acts like a small shock absorber, and contains its own separate oil supply. The compression and rebound damping are both controlled by this small "shock" chamber. Being dual chamber, you can run different oils in the inner chamber and the outer leg. Many are running synthetic ATF in the inner chamber (about 7wt) rather than fork oil, synthetic 0w20 motor oil in the outer leg for stiction free action, and use the outer leg level to adjust bottoming control. Apparently the slipperier the oil the better they work, hence why the synthetic ATF is favoured over the 5 wt. fork oil. I haven't been able to test this yet as it still -15C here with snow. The disassembly and oil changing looks formidable but is actually very easy and can be done with regular tools. Polishing the damping rods with some #800 emory makes a noticable difference in how smooth they stroke. Cam.
Tools:
2" box end wrench (or huge cresent wrench -they are not tight)
13/16" (21mm) socket
1-1/4" (32mm) socket
17mm wrench
med cresent wrench as a damper rod stopper tool.
