1977 kz1000 b charging issue

My bike has a new gel battery but having a charging issue. Battery has 12.6 volts. I start bike and at idle with lights off it raises to 12.8 volts. I then rev it to 4000 rpm the volts go up to 13.6 volts. I then idle it back down and turn on light volts goes to 12.3 volts. I then rev it to 4000 rpm volts goes to 12.6 volts. What direction did I go? Thanks

Sounds like a weak stator.

I suggest you use the troubleshooting instructions int he Kawasaki Service Manual to isolate the problem, I had a similar problem years ago and it turned out to be a faulty rectifier. The troubleshooting instructions made the source of the problem very easy to find. Ed

I checked my complete charging system out per service manual. Everything checked out fine. I then took headlight out and was checking all the wiring there and all looked fine. I then checked the wattage of the bulb and bingo the previous owner put a 100 watt headlight bulb in it. I then put a stock headlight bulb in it and all is fine now. The guy put about double the wattage that is supposed to be in it. I bought this bike about 6 months ago and haven't driven it much as I have several other bikes in my stable. Thanks for all the help on here.