My bike is the same. Starts cold and only runs smooth with choke. Usually start and let it run while putting on my gear. I turn off the choke after about 4 blocks running. Total time with choke is about 3 minutes. Otherwise the bike runs very rough until it is warmed up. No drips from the overflow on my bike. I have tried starting with half choke but no go. It just doesn't like it. Needs a little choke even if very warm. I am sure all bikes are a little different and trying different start routines will eventually result in one that works for your bike. Good luck and ride safe. ;)