Topic: Solid State rectifier/regulater conversion

[ilmod1]

I am restoring my father's 1975 CB750F that had been sitting in storage for 20 years and I keep draining the battery while adjusting the carbs etc. I am only getting 12 volts at idle and a unstable 13 volts at 4k rpms. It has the original mechanical regulator and large diode rectifier. I am about to replace them with ElectroSport ESR240 Regulator/Rectifier. Does anyone have any pointers about wiring or this manufacturer, anything I should look out for?

[calj737]

They tend to be plug and play. You may need to alter the mounting plate a tad to accommodate a single unit, otherwise they're pre-wired with a compatible plug.

But before you go off and spend money on a R/R, best to first diagnose the actual cause of your charging ailments. Idle voltage is low in all CBs. These bikes don't make surplus voltage until above ~2,500. "Unstable @4k" isn't much of an explanation. Typical problems are:

• Poor battery voltage
• poor ground
• corrosion within the harness
• poor connections from stator harness to R/R plate

Can you disclose any specific diagnostic steps you've taken and their results to determine that it is indeed your R/R? you can use this diagram to assist you-
http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf

[PeWe]

You can get the old stuff to work fine again. Clean all contact points in connectors involved from alternator to  regulator and rectifier. Make a service of the regulator as described in the manual, adjust it and you'll get 14.5V when you should.

I had bad charging too after over 20 years of no use, mostly in dusty barn.

[Jerry Rxman Griffin aka MuthaF'er]

I expect you are using a new battery? If not put a full charge on it and have it load tested. Are you keeping it on a tender? These  batteries do not have a lot of excess capacity. The system does not begin charging until 1700 rpms.