Battery not charging? Might be time to replace your rectifier or regulator, and why not replace them both at once with a part that will work better than the originals. This Rectifier / Regulator Combo will replace both your old rectifier and regulator. Unlike many other units, this regulator rectifier is designed to work with lead acid based battieries, including Gel batteries as well as lithium batteries. You must have a fully charged battery in perfect working order before installing a new regulator rectifier.
Dimensions: 82mm Long x 30mm tall x 80mm wide
Mounting Hole spacing - 66mm (measured center to center)
Replaces these Honda OEM part numbers: Rectifier: 31700-333-008 Regulator: 31400-300-035
We also carry a terminal connector kit if you need to replace the rectifier connection on the stock wiring harness. If the stock connector is brittle and the terminals are corroded, it's best to replace it.
Here's a very helpful SOHC forum thread on testing the charging system
Note: The white 5 wire connector plugs into the stock wiring harness, replacing the old rectifier. The 3 male spade connectors plug in where the old regulator connected. Corroded / loose / damaged wiring is a very common cause for charging system issues, make sure all connections are clean and secure. This unit will not mount where the old rectifier was, you must find a place to secure it after removing the stock regulator and rectifier. The body of the unit does not need to be grounded.
CB350F - 1972-1974
CB400F Super Sport - 1975-1977
CB500K - 1971-1973
CB550F Super Sport - 1975-1977
CB550K - 1974-1978
CB750F Super Sport - 1975-1978
CB750K - 1969-1978
Designed to work with 3 phase charging systems on pre-1979 Honda SOHC4's
Posted by Michael Morrison on 24th May 2017
I took a chance going with the cheapest combo unit I could find and no reviews at the time, but I am very happy with this unit. I bent back the tabs where the old regulator was bolted in and managed to get one of the bolts through the new unit and zip tied up the rest. Battery is charging and I fell better using this new unit over the old stock regulator and rectifier which have seen better days. Everything hooked right up to the stock harness and wiring, no modifications needed. Would recommend!