Honda chose to connect the charging system on the CB/CL450 via the handlebar light switch so only 2/3 (maybe even 1/3) of the generators charging power was used with lights off. As I understand it one of the reasons for this was that the older type of rectifier could not handle the resulting increase in current.
To get around this I bought a modern 100V 25A silicone rectifier from a radio store for $5 and bypassed the reduction in charging in the way Mike describes here.
[attachment=2:nfefu44q]Rectifier 100V 25A - 02.jpg[/attachment:nfefu44q]
I moved the old wires and contact to the new rectifier and connected the wires as follows.
Red/white to +
Green to -
Pink and yellow to AC. Doesn't matter which goes where as they are interchangeable.
Then I installed the unit where the stock one goes and now I have a really well working charging system with full charging all the time.