if you dont have to choke your bike to start it, that means your pilot jet is too big. sounds like you need to drop down one size. this is also probably why its hard to start later on. the bike is loading up with fuel/oil from the pilots being too big.
have you rejetted your bike since it turned warmer out?
also, what is your gas/oil mix ratio and what oil?
what are your mods? elevation? temps?