I posted this originally in the Like 200i section, but noticed people with Downtown 300i's and possibly others also had it, so I thought I'd share this possible simple solution with you.
This is for people who have ONLY had a problem with hard starts when the engine is dead cold after the bike has been sitting in direct sunlight and have the common modern style gas cap that has a metal hinged tab that you flip up and turn to remove and install.
I noticed that there is a vent/overfill line coming out from the fuel filler area under the cap, and realized that when you have the cap turned as far to the right as you can the line gets blocked. So I tried turning the cap to the left after putting it back on on locking the tab down. (It's locked down and only goes a little to the left.) Well, since then I have started it under the same conditions with the same instant starts I get in any other conditions. So either it's highly important to keep that line unblocked, or the engine is coincidentally "healing itself" with more miles at the same time I tried this experiment. Hope this saved some headaches.