are you keeping the choke out? As Bouncingradical says, carbed bikes can be very cold blooded and need time to warm up, esp. in the winter…you have to give it a fair amount of choke…or however one describes using it…maybe it’s *not* giving it choke, but you know what I mean.
Your owners manual should tell you, when using the choke, what rpm range to keep in the engine in while you’re using it.
Pull the choke out when you start it, and then gradually back it off to keep the rpms in that range as the bike warms up. Pretty soon, it’s all the way in and the bike is running fine.