What is the Kawasaki kx 125 compression i did test tested 135 with cold motor is this what it shuld be i get real bad bog at low rpm

check and make sure choke is opening all the way,if it is only opening part way could explain why you don't need to use choke at all to start and then at higher rpm's it is not getting enough air causing it to basically choke it self out.

Hey Steve
Put a new spark plug in first...
... Sounds more like a fuel delivery issue... (the jests are in the carb and are considered one item). IF THE ENGINE HAS BEEN MODIFIED - FIND A REAL PRO THAT KNOWS HOW TO JET AN ENGINE - I CANNOT STRESS THIS ENOUGH - THIS IS not FOR AMATEURS!!
Make sure you have fuel flowing to the carb..(turn the gas off at the petcock - remove the gas line and then turn the gas on -- if its flows quickly and a full stream - turn the gas off, reconnect the gas line. Now, on to the carburetor... IF you are a great mechanic, you can clean and set the carb..IF NOT - take it to a qualified pro!! After the carb is cleaned and set.. it should run great...
Please reply to me when you are done with these steps..

to seat the screw it goes all the way in but only 2.5 turns out

adjust more if needed

good luck.

is the compression good on your engine have you checked and cleaned the carb out also are you running the right pre mix ratio about 32:1 which is about 156 ml oil to 5 litres of petrol

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

32:1--40:1 any less than 40:1 And you take risk of damaging engine(crank and top end),Any more than 32:1 and it will smoke real bad and foul spark plugs alot.....

Could have low compression or bad reed valves, if you take your hand and move the kick starter is it easy to do? i would do a compression test.

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

have u cleaned the reed valve out?