Like said above, normal on some oils or too rich
I have been told (and believe) by some, that some of the milking is due to the condensation inside the motor. Due to the cooling effect of alky and the massive air these one cylinder motors take in the breather when the piston is going up. Unlike a v8 that has another piston going down when one is going up so the breather doesn't move as much air from the outside.
So it would be worse on humid days... Like this weekend
As also stated above changed oil once a day, if 2 runs or 10.
If it ain't broke, keep fixing it until it is!