I've got about 940 miles on mine now and when it first starts up from being cold I will get a slight hesitation and stall but once I get rolling and the bike truely is warmed up, there is no hesitation at all. I did have couple of times when warm it wouldn't start right off , choke or not, and I had to give it a bit of throttle to start. As soon as it warms up a little more I will order a new exhaust pipe and jet kit and wake up this sleeping 250!
Welcome aboard!!!

 

Honda fan is OK... but Yammy? Hell naw, can't roll with the blue bikes.

 

The bike will run better after the miles start adding up, the rings are seating and sealing the compression better. Once you get about 100 miles or so, it will be pretty much broken in as long as you vary the RPM's during that 100, and don't over-rev too much. After that, it's ready to rip.....and time for a re-jet and airbox mod. That will unleash the 250 that is lurking in your bike.