How new is the battery?  If it's more than a year or two old, it may be time for a new one.  These little batteries don't last long.

Second idea: are you still using the original rectifier?  It would be bright orange and square in shape, if that is the case.  Change out the rectifier if you have not done so.  There is a sticky at the top of the electrical forum that goes into more detail.

Adam
Flathead Valley, MT, USA
1976 CT90 - Shiny Orange
1973 CT70 K3 - Candy Riviera Blue
1970 CT70 HK0 - Candy Blue Green (project)
1979 Z50R - Tahitian Red (project)
1964 CT200 - Scarlet Red (project + extras)
1968 CL175 K0 - Dark Blue (project)
1978 NC50 - Pal Green (project)
1982 & 1983 CT110s - Monza Red (projects + extras)