Sherco 250 2004 starts first kick when cold but I can not start it when warmed up, if I pull the choke on it will fire up straight away, it runs ok when out but don't no why I have to put the choke on every time to start it any ideas ?????

check float level in carb first.

Could be pilot jet plugged or too small

Would tend to agree with Dave there, although I do not quite understand your post.

So it starts fine off cold with choke.

I would presume that you are able to turn choke off after initial start and the bike continues to run fine? Untill shut down and restarted?

If you(as example)are having to leave the choke on for it to run fine, that in itself is a problem.

Anyway, the carb should have a good cleaning, which means removing the jets and I usually recommend passing a fine wire through the pilot jet as they are difficult to see through. Clean the banjo screen as well, Blow air or carby spray then air through everything, should be able to eat off the thing when done! Clean means clean!

On the other hand, some may also tell the same as me, as when the weather is cold, one can putt about a bit, going round section to section, and never really develop a lot of heat in the motor. They will cool quickly while you are walking a section, then require a bit of choke on a restart.

Throw in a fresh plug too, if you have not!