Originally Posted by grizz1

The main reason the motor does this is the wide idle gap (masking the rich bottom end). It's the idle gap that is key here.
If you don't reduce the idle gap you will be chasing your tail all day for a tune. Adjusting the needles without reducing the idle gap will most likely not fix the problem. This situation of the wide idle gap / rich bottom end nearly always results in the HSN being too lean, because this is the only way the motor can run with such a rich bottom end (remember the HSN regulates the amount of fuel the LSN receives). The motor will run OK, but not to it's maximum performance. Quite often you will notice the motor lean bogging at the bottom of the tank and coming in hot. Another tell tale sign of the wide idle gap / rich bottom end is the motor holding it's revs and screaming when you go over a jump.
With the correct idle gap / mixture the motor should come in after a run and idle nicely straight off, then slowly load up over a period of time.