Hi Firstly i'm new here so all the best for xmas to everyone on this site
About the problem, I had a 1992 CBR600FN in that was overcharging, so I replaced the rectifier and battery as it was cooked. Two wks later the guy is back flat battery this is where the fun begins. The rectifier is not kicking out enough to charge the battery (13.5V at 5000 RPM) the rectifier type is a SA633-12 T8.8, however at just below 2000RPM it is showing a healthy 14.6V rev it and it drops.
So I changed that for a SA633-12 T9.9 and it now kicks out 17 volts at 5000RPM.
the above are the last checks that I have done, to date I have replaced the complete wiring loom, stator, rectifier x3, battery x2 Magneto/flywheel, which I have tried on a 1998 CBR600FW where each swapped component works with no problem
Any Ideas
Scott