I'm in trouble shoot mode trying to figure out what has changed since I last rode my bike 3 weeks ago. The bike was hard to start today and would not idle either with the choke on or off. With choke off, the bike was popping while giving it just enough gas to keep it running. I rode it a few minutes but nothing improved. I removed the carb, float bowl, all jets and float. Cleaned enerything with carb cleaner and reinstalled. Put a new plug in and fresh gas. Bike is still hard to start even with choke on. Once started it will not idle and does not pop as much. I turned the pilot screw 1.5 turns from the seated position. Should the idle screw also have the same 1.5 turns out? What is the standard on resetting the idle adjustment? When reinstalling the slow jet, is it possible to overtighten the jet? The bike is set up as follows: pilot 1.5 turns out, #42 slow jet, jet needle NCYQ in 4th groove, #168 main jet, sea level @ 75 degrees. This on an '06 CRF 450 with 7 original hours on it. Thanks in advance.

check your valve clearances first.

After that you are about stock jetting there. Should not be a problem. I would check the hotstart make sure there is slack in the cable.

Try replacing the pilot jet.