Still out everyday here . Currently 23c so i went out for short blast, was a bit cool though i'm gonna have to start wearing my leathers as opposed to the airtex jacket and jeans.
I think you will find that cold air has more oxygen per cubic meter than warm air.
Therefore in the winter for each inlet stroke the bike sucks in more oxygen in the fuel air mix and the there's a better explosion when it sparks.
Has anyone noticed that the exhaust sounds better in the cold? This last week the bike, once nicely warmed up, has sounded awesome! Could just be that cold air better transmits the sound to your ears of course.
One thing though: the bike is really hard to start once it gets sub-zero. Even when used every day. It just seems to be a few degrees that make the difference (+3C was fine). I guess that is the nature of carbs.