Newbie to Newbie(Star Wars?),
Going on 2nd summer w/2002 KDX 200. This is a combination of thoughts and advice learned on this site w/a dash of personal experience.
1. Dont spend too much time w/ the factory chain/sprockets you will need to change them soon. Some sort of rubber alloy...? But to make it last, clean w/ brush or whatever and lube.
2. Went w/manual for tranny oil - 2050 summer 1040 fall/wint/spring - many do use synthetic. Everyone swears by their brand/weight, but I've yet to hear of one type(proven) to out performing another.
3. Buy a manual - repack all bearings. I haven't had a bearing problem, but heard enough convincing info to do it - doesnt take alot of time anyway.
4. Also went w/32:1 Maxima SuperM - again, seemed to be popular and along w/the oil,...I've yet to hear of one type(proven) to out perform another. Lots of good oils on the market - pick one.
5. Don't sweat the break-in scare in the manual. Sounds like your ready to rip.
6. Print a copy of "Carburator tuning" by Canadian Dave, read it and rejett.
This should get you started, I have my bike tweaked to meet and beat my W. Pa. riding areas. I ride/rode w/ some great riders and rode side by side - be patient, ride for a while and tailor your bike to meet your riding conditions.
Good Luck