have to pour gas in carb to start but runs fine after that

I swapped a kohler courage 19hp motor on a mower and now I must put gas in carb to get it started , it runs fine after that at full throttle for 2hrs so its not the fuel shut off silenoid or the float or jets and bowl is clean . it will fire back up after running for a while but after a week it wont start again till I pour gas in carb ,what could be the problem ?

choke not closing all the way.