My daughters KDX has gained a new habit, failure to start after a tipover. This seems to have started after a topend job and kips service but I don't know what the connection would be. Today she crashed in a mudhole and sure enough it didn't want to fire up. A quick plug swap and it starts up again. In the past I had trouble getting it jetted but it has seemed about right and runs pretty well.
Sounds like there could be dirt stuck in the needle and/or seat. If the float is sticking or the needle is not closing tight, the bike will foul plugs real quick!
Wait, not so fast... did you say "Daughters KDX" Way to go!!!
I have one as well, I stole some of the "good parts" off hers, gold valve, rad guards (I tend to bounce and crash harder). I suppose pulling the carb and cleaning everything out would be wise.