why do bikes run better after a thrashing?

Some days the bike just runs nicer, smooth and zingy rather than lumpy and unzingy, I guess the humidity, temp of the day etc have an influence on how nicely the motor runs. But, the motor always feels really nice after I've thrashed it a bit, i.e. zingy.

So what is it that does this, what changes in the motor to make it feel like this?

Cheers

why do bikes run better after a thrashing?