Suzuki
From Noah.org
Carb Needle and Jet
I just did carb modification using the a Dynojet kit. The bike now has a much wider power band. I can slink around tight corners at low RPM without lugging or having the power drop off. The bike doesn't sound asthmatic anymore. I'm using a stock exhaust, so it's not much louder. There's a bit of a deep purr from the airbox opening. So it sounds great, but nothing the neighbors will complain about. Best $80 I've spent on this bike. I also added allen head screws for the carb bowl and an extended fuel screw -- added a trivial amount extra to the price.
I got my parts here. These are real nice people and helpful. Kientech
Notes
DR650 Wiki at Wikia DR650
Other parts
Moose Racing hand guards http://www.mooseracing.com/catalog.jsp?level1=1151&level2=1176&level3=1178&level4=1181&product_group_id=5351
The running lights and tail lights of the Suzuki DR650 use an 1157 bulb. You can install an LED replacement. These don't break as easily if you fall down or burn out if a little water gets in the tail light case. In fact, you can solder them in to eliminate any chance of a loose connection due to corrosion.
http://www.procycle-online.com/bikepages/dr650.htm