Pilot jet size???

[keithpincock]

I just bought a new left over 2007 trx250ex. When I got it home it would not idle, ever. The pilot jet was plugged. I bought a new one the same size, 42. Then it ran really rich. I cleaned up the original jet and put it in. It was a little better but still rich. I have the fuel screw almost all the way in and it will still start cold without any choke. In the FAQ section he says that he uses a 38 that he makes it sound like comes stock. Is a 38 closer to what I need? Anything else I am missing?

[Jetdrive]

Your OEM jet is a number 42. You may be running rich due to the fuel screw being out too far. Turn it all the way in then back out 1 7/8 turns from full in. This is the initial setting from Honda. Start up let it warm up and adjust the fuel screw until idle is smooth. My idles great with the screw set at 2 turns from full in.
If this does not fix the rich condition make sure your choke is full open when knob is in. My choke cable clamp came loose once and the choke was not working properly. I readjusted the end of the cable outer sleeve and tighten the clamp srew on the carb bracket and it now works well.
The last thing to check is the air fillter. If it is over oiled after cleaning it will affect low speed jetting. Also check the airbox snorkel for any blockag, it may cause this.