Probably the best investment I ever made on that KDX was buying the service manual from Kawasaki. That thing was very well detailed and told you exactly how to do everything! The manual cost me $37.00 in 1991, and it was worth every dime!

Changing the power valve spring is easy- pop the clutch cover off, push, twist and dissemble the power valve gears and couplings (not much there really), then release the spring, replace it with a different one, then stick it all back together. It takes about forty five minutes.

The "upper part" of the KIPS (the gears and valves in the cylinder)- Unless you are mechanically inclined and can figure out a 3D puzzle of "this gear goes here this way, because it has to turn the half-gear that turns that other gear, so that all of the valves open and close together in perfect unison at the right time"- then BUY THE SERVICE MANUAL, it will save your ass.