this is a Ltf250f 4x4. 4 stroke this thing has been sitting for a year ran fine then. i drained the tank tore the carb down and cleaned it still wont run right.this has no choke it has the inrichener if i turn it on fires brifely then stalls(will not run with it on) trun it off fires brifely then stalls. it will run if i take the air cleaner out and cover the air inlet with my hand (baiscly chokeing it ) but if i remove my hand all the way it will stall within a few sec. if i warm it up useing the hand chokeing way it will idle but ruff there is a pop in the motor sometimes(witch it didnt do be for) i pulled the plug and cleaned it.it was black it has been run for may 45 min. pulled it again and now lite brownish white. im stumped here. could it be a bad plug ????????? thought i should add there is only 280mile on it.

thanks in advance

 

tryed a new plug no change still all the same

 

If you use 1/4 throttle to start and run...will it run? Is the problem only at idle?
Hows the idle speed...could it be too low? wheres the mixture screw set at?