I have an Suzuki RG125 1993 fully rebuilt and a great runner. BUT it will not start when cold without a hand over the airbox intake to ”choke the engine” then she fires perfectly and runs ok , choke on etc… I have stripped and cleaned the carb loads of times, this tends to fix the problem once then next day same problem. Could the choke tube be semi blocked?, the only bit I can’t take out and clean? Otherwwise the bike runs perfectly,
Squirt some sort of cleaner or wd-40 or air through the choke passages and make sure it goes all the way through. If it doesn’t you know it’s clogged and you can soak the carb for a while.
Also – am I correct to assume the carb butterfly is working properly? The spring return mechanism can sometimes become faulty and it won’t open/close as it should.