I did just put this bike together and the plugs have less than 1000 miles on them. I checked the valve clearance while i had the engine out. The engine has around 20,000 on it now. I'm sure its not the choke. It would only run better when it was warm if the pilots were plugged or the carbs were really dirty. Its around 65 out now and I let it warm to about 150 today and it was runnin good after just few minutes or riding so i think the weather has a lot to do with it. That or it just needed to be rode cuz this engine sat for about 2 years before i got to get it in a frame.