I have had continuous probs with my yz426f 2001 starting in all sorts of conditions. Cold,after a fall down and cold mornings. My brother has a 2000 yz426f and starts alot better than mine. He told me about the light blue wire trick. The bike starts @ 30deg F all the way to 60deg F NO PROB! 2 other things to remember if you live in Mich. or another comparible state as far as weather goes you need to make sure when temps are AVG. below 40deg make sure you have what they call "WINTER" gas. They change the formula's between summer and winter at all gas stations in states like michigan. Also he informed me that the air filter is very sensitive to much oil. I recommend not using very sticky air gunk. What we use is deisel fuel to clean it and ring it out with Mobil 1. But use what ya feel confortable with but DON'T USE ALOT it will foul out plugs everything on our bikes is presently stock including jetting....Enjoy the riding!!