KLX 125 sat for 2 years, carb removed, cleaned, cleaned, cleaned, re-installed no air filter restriction, runs great at 600- approx 2500 rpm then 2/3 throttle to full throttle, bogs. all passages appear clean on main jet, float level good, good compression, ran fine before storage according to previous owner

Sounds like the exhaust is clogged with carbon.Remove the silencer and dismantle it if you can and clean the pipe and baffles.This should help you.

make sure u have the right compression and after 5 years of not kicking it a 300 is probably pretty tough to kick. but u should be ok

Be certain the battery is in good condition. Install a new spark plug. Clean the carb and air filter. Use the throttle sparingly. The carb has a power valve that gives an extra shot of gas each time the throttle is twisted. Too many twists and the engine floods out. Please rate my answer. Thanks!

Down is choke "ON" and up is choke "OFF". Had same question and found on another site. Made carb adjusrment much easier after cleaning. Bike was new to me and runs great now.

The jet valve in the carb may be blocked. Or your carb dismantling job was not as good.

ckeck air filter,you may need to rebild the carborator. i have two klr 650's my self. ckeck ebay for replacement carb.

when riding try pulling choke u p and see what happens

try cleaning the air filter. Doesnt seem like a big thing to do but it will make a world of difference

i'd say the carb is gummed up especially the pilot jet (#16158) in this pic of the USA carb. may have to remove the carb & bowl and then remove the pilot jet (w/ flat head screw driver) and clean out the tiny holes.

http://partsfinder.onlinemicrofiche.com/atlanticcycleandpower/Kawasaki_OEM/KawasakiDB.asp?Type=18&A=39&B=17&Action=O

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the carb slide is installed backwards (turned 180 degrees). its #16025 in the pic. i've done this before on my daughter's XR70 and Z50. you'll know if its this when you move the choke lever, RPMs increase and decrease.

hope this worked for you and was fast enough.

I have had several bikes in my time. and keeping the carbs syncranized is very important. Did you put aftermarket pipes on it? try rejeting the carbs up 2+mm that may help the fuel air ratio?