I have a 2001 Artic Cat 400. I just replaced the carb and still have the same problem. It will start cold or hot but I have to keep the choke on. If I take choke off it coughs and backfires, runs poor. This Artic Cat has always gone through spark plugs really fast.

 

Check the rubber boot between the air box and the carb for cracks, replace if you find a crack. That will make it run lean plus suck in dirt. Normally, I would say check for a speck of dirt in the pilot jet. Is the PMS screw turned out 1-2 turns? Float height set to 17 mm?

 

Thank you, I will check on them.