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.
Excellent writeup Ronny, I've made it a sticky. Do you have a link to one of these rectifiers online?
So, since I'm useless at electrics I have to ask, can this same setup be used on the other Honda twins (namely my 350 )?
Thanks! These rectifiers are available everywhere at radio stores and electronics shops. This conversion should work on all older Honda twins with a single phase generator but they may have different color coding on wires. I'm not sure but I think the newer CM/CB 400/450's has a 3-phase generator needing two rectifiers and the more complex connections jayel shows for the XS650. You can spot the difference if you have pink, yellow and white wires (single phase) or if you have 3 yellow wires (3-phase).
As frogman says the result are the same as Oregon Cycles rectifiers but way cheaper.
might want to bolt it to a piece of heavy guage aluminum plate as a heat sink, there is a modification using two rectifiers like this for the XS650 and they recommend at least a 2"x4" heat sink
To be absolutely safe it's a good idea to bolt them to some kind of heat sink as jayel suggests. At first I was thinking of a using a heat sink from an old computer processor or a graphics card but decided to try without one. I did a 90 mph 200 mile stint on the freeway last summer without any problems.
Post subject: Re: How to make your own replacement silicone rectifier.
Posted: Sun Apr 17, 2011 4:46 pm
Joined: Thu Sep 25, 2008 7:40 am Posts: 15378 Location: Stephen Lohmeyer,3839 Sun Valley Lane, Roanoke, Virginia 24014 540-525-5199Sixtysixsprint@aol.com
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I have a problem with Jayel's drawing (I think he forgot one wire).....The right side rectifier only has one AC wire "feeding it".... it takes two wires to comprise an AC input....( the rectifier has to be connected to both ends of the output coil )
Steve I think Jayels drawing works. The right rectifier is letting one phase use the diode between ~ and +.
EDIT: I correct my self. One phase uses two diodes in the right rectifier. The diode between ~ and + but also the diode between ~ and -. Pretty clever design that makes it possible for us to make this modification on the newer 3 phase Honda twins too.
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