I sold my KDX200 when I bought the KX250 and I am not sorry I did. The KX has really bit power, but once you come to grips with it, it is a pleasure to ride. The Flywheel weight does help matters. This is my setup on my KX for off road/enduro use:
IMS Long Range Tank, O-Ring Chain, Bark Busters, Hyde Bash Plate & Exhaust Guard, Fly Wheel Weight (300g – 11oz), Twin Air Filter, Rethal bars(Standard), Jetting: Main Jet 155, Pilot Jet 45, needle in the 2nd clip form the top,air screw 2 turns out (Standard 160/48, needle in 2nd clip and air screw 1 ½ turns out), Sprockets:13/48 (Standard 13/51), Suspension: Forks: Compression 11 clicks out, Rebound 18 – 16 clicks out (Standard comp.11, rebound 11), Shock: HS Comp. 1.25 turns, Comp. 12 clicks, Rebound 10 clicks out, sag 100mm (Standard setup), Front Tire: Dunlop 755 (standard soft), next tire Metzler MC4 (soft) Rear: Metzler MC5 (Intermediate), Standard was a Dunlop 755 (soft).
This was my setup on my KDX200:
Pro Taper Bars, Bark Busters, Hyde Skid Plate, Armadillo Exhaust Guard, Bridgestone M402 rear and Kenda Millville front Tire, Sprockets 13/47 (standard), O-Ring chain, Kawasaki OEM .37kg/mm Fork Springs, Sag set to 90mm on the standard rear shock, FMF Gnarly Pipe, Powercore 2 Silencer, Boyesen Reed Petals, Twin Air Filter, Modified Air Box Lid, Jetting 160/48 (standard), Flywheel Weight 18% to come (approximately 220g), Black MX Front and Rear Fenders, plus a number board, Frame Guards and aftermarket plastics all round, Homemade Guards for the forks and the swingarm (I love the rocks - black 5mm irrigation piping)
FX Gripper Seat Cover (FX07-21132).
KX Rules!!!