I'm having slightly the same issue. My engine runs so great, but it won't start or Idle unless the choke is pulled out half way. I have to have it in the middle. I just bought a new bike with a honda 5 hp on it, and it was running horribly until i snagged a carb off my other honda engine. Now i'm just having problems with choking it. Same thing you think?
How would i fix my fuel from running too lean?