YZ425F Does not start in Cold/Cool Weather

My 2000 YZ426F does not start when it is cool outside. That is, when the temperature is lower than 60 degrees. I live in Missouri and I am not able to ride in the winter. Any recommendations would be appreciated.

Have you checked the valves or replaced the spark plug lately?

My 2003 YZ450F needs a couple of twists of the throttle when it's cold, I also turn the idle up one full turn.

My 2003 YZ450F needs a couple of twists of the throttle when it's cold, I also turn the idle up one full turn.

Ya.. that usually works for me too. Just dont twist the throttle while kicken it over. Dont do it more that 2 or 3 times either, or you will flood the engine out.

If it's not spark plug or valves then be sure and check your ignition stator!!! I intallled an ICAT Igniton module, and that seemed to help cold starts alot.

My 2000 YZ426F does not start when it is cool outside. QUOTE]

Cool air contains more oxygen than warm, so your bike gets too lean mixture. You need to open up the fuel screw half a turn (counter clockwise). This should help. You perhaps also need to go for one larger main and pilot.

Turning the idle up (clockwise) one full turn is a good idea too.

Actually the main wouldnt change starting at all, but if it needs a larger pilot because of the cooler air, a larger main is probably wise for the most top end. But as mentioned start with the fuel screw.

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