I cant get my 2003 kx 125 to run properly

Sounds like there could be a problem with the main jet not delivering sufficient fuel for normal running. Clean out the carb and check the jets and passages for obstructions and dirt.

change the plug then drain the carb and ck compression and that will tell u the story

check the carb float and the float settings. also clean all the jets out. check the joke aint sticking. check the condition of the air filter for rips or holes as that would explain why the bike is bogging when reved

first drain the carby, then set your air mixture screw 2 turns out, from the fully turned in position. The starting proceedure is as follows, when the engine is COLD, turn on fuel, pull on the choke fully, and kick the engine over. DO NOT use any throttle, when the engine is cold, and the choke is on. Remember Choke on, NO throttle.
When warm, no choke, and a little throttle when kicking.

sounds like you need to rejet the carb..

Hello you have a
1. fuel starvation problem clogged carburetor jets.(clean the carb)
2. Intake leak carb joint/intake manifold.( start your motor get it to idle best you can spray wd40 around the carb joint if the rpms change you have a leak replace the carb joint or gasket/o-ring as needed.
3. crankshaft main seal magneto side leaking or worn main bearing.
check end play on the magneto side remove the cover plate firmly grab the end of the shaft with up an down motion if you can feel it move replace the main bearings and seals.
These are problem that will cause your motor to run lean and hesitate.
Hope this helps you with your problem

the idle buddy is too low,on the carb is a screw the ide screw turn it in 1/4 of a turn with the bike running untill it idles the way you want it too and it will idle the pic below ill help ya buddy

clean your carburator, and if possible do a compression check, how longs it been since you replaced rings and piston.

sounds like your idle jet is clogged, remove your carb and clean idle jet cause it won't idle or kick start without it...good luck to you friend...Tim

get the bike started, hold the engine at a high idle. while holding the idle high, adjust the air fuel mixture screw until it sounds smooth. rev it up a few times and see if the engine is "snappier". let it return to an idle, then adjust the idle screw. it may take a few tries to get it right, just listen to the engine.. if this dont work, you may consider re-jetting the carb. hope this helps...