Motorcycle Repair: Charging system, volunteer services, charging system

Question
I have a 1982 Honda CB900F, I brought it in July of 2005, since I have had the bike it was draining the battery, if I do city driving the battery would not hold a charge, if I did again highway driving the meter reads a 12 volts, sometimes just over or under, when I do city driving it somewhere around 10 never 12, that's when the battery loses its charge, i asked a friend about the problem he said it could be the voltage regulator, so I changed it, the problem is still the same, I got a new battery and this seemed to solve the problem for a short time, I then had the rotor checked it read 4.0 on the multi meter, that checked out O.K. I had the brushes on the rotor checked they looked good, if I do highway driving, I have no problem, If I do city driving I have a problem, if I disconnect the fuse on the headlight the charging system is working fine but I need that light, I have done no other work on this bike except change the tires and new chain  

Answer
Hi Anthony,

I suspect the alternator is not working properly. I would need to perform a few checks to accurately diagnose the problem.

Visit this website and follow their "Fault Finding Chart."

www.electrosport.com/electrosport_fault_finding.html

I recommend their fine parts over OEM parts.

I return test and repair information files by email. There was no email address with your question as requested in my instructions. Email makes my volunteer services here possible.

Respectfully,
Mark Shively