The biggest increase I have come up with so far has been a reed spacer for the stock reed cage. I have boyessen reeds and they weren't any improvement over nearly new stock reeds, even after rejetting.
Reed spacers get mentioned every so often in passing, but get very little "press". Does anyone have experience with them?
I couldn't find a source for kdx so I made my own. copy the reed gasket on to a sheet of 1/8" aluminum. much drilling and filing later you have it. I used 2 gaskets on 1 side and 1 gasket on the other side so it spaces it out about 3/16". You can"t go much more and still get the carb on.
Not personal experiance Jeff, but Doug, my riding buddy, put a spacer on his KX500.
He said it really helps. I don't know how it helps, I didn't ask what improvement it made.
Jerry
I'd rather be a smartass like carvr, than a dumbass like.... well, you fill in the blank!