Flying machine prime pump to continue running

Hello, I have a 200cc 2 stoke using a Walbro WB that will
only cold start when I pump the primer bulb until the engine warms up. After the engine warms up a bit, it runs very well and starts without a hitch. The fuel line is good as well the primer. Carb is all sealed up no vacuum leaks. No blockage of the fuel passages. 
Thanks, Greg.