Re: too rich fuel mix?
its important to measure your mix, im not going to go into details about the the correct oil-gas ratio is because it will start a ****storm.
manufactures recommend 16:1 break in most run at most 20:1.
if there is too much oil then yes it will bog down as oil does not burn as well as gas and with a set amount of mix flowing through the carb you will have less gas and thus less power. The carb may be tuned perfectly and thus it isnt "rich" technically, but you might experience some of the same symptoms.