4 stoking when cold

This is the deal.. first thing in the morning when i start my bike up, i usally have to choke it . it fires right up and i let it idle for a minute or two then take off the choke. i rev it it up and let it idle again for a minute. okay so i take off and get out on the main road but when i get up to 3/4 throttle it starts to 4 stroke so i lay off it till i get to the store 5 blocks away. i shut it off for 10 min then start it back up and take off. then ther is no problem . i get on it to wot and its perfect.
could this just be that it needs more time to warm up or maby it needs to go a size smaller on the jetting? The plug color looks nice and chocolty like it should.
Or maby just not mess with it since it runs fine when when it seemingly is fully warmed up?
Thanks for the input..

well ,i discovered the problem. i was kinda stumoped. then i remembered a tread i read about if you have a high power cdi that you can go to a larger spark plug gap. i checked the gap on my plug and it was .28 so i opened it to .33 and now no problem.
Its amazing how something so simple can do so much..