Re: She Just Ain't Climbing Like She Used To - Standard China Girl 66cc
Has the weather changed since you first got it running? Have you done any jetting, or are you running the stock jet? Have you changed the oil ratio over time? Just fyi as you change your oil ratio, you need to change your jetting to compensate.
Less oil = richer
Stock jetting is usually on the rich side.
Since it sounds like your motor is in good shape, if all else fails try an expansion chamber. The one from SBP works well.