Original rectifier and regulator units were a product of their time and while they did a fine job charging the battery then, electronics have come a long way in the last 50+ years. Our modern combination regulator and rectifier unit eliminates original units that commonly fail and make your charging system rock solid. This guide is intended to demonstrate how the replacement modern combination regulator rectifier can be mounted in a neat manner to the electronics tray with a few quick and easy modifications.
Compatibility
CB500 K0*
CB500 K1-K2
CB550K - all models
CB550F - all models
*CB500K0 models - Early versions of the CB500K0 used a unique round pin style wiring harness connector. The regulator/rectifier can be installed on these models without issue by replacing the wiring harness and new regulator/rectifier connector with our replacement 6-pin connector. The difference is that the mounting of the regulator/rectifier might differ slightly due to the unique electronics tray design.
The Electronics Tray
The original Honda CB500K, CB550K, and CB550F electronics tray can be found under the left side plastic cover.
Rectifier - The original rectifier is found at the bottom of the electronics tray. It is bolted to a specialty stud and mounts the rectifier to the tray through the middle of the rectifier. The rectifier plugs into the main wiring harness using the bottom 6-pin connection on the electronics tray.
Regulator - The original regulator is found on the right side of the electronics tray bolted behind the fusebox. 2 bolts secure it to welded nuts on the electronics tray. The spade connections for the regulator plug directly into the 3 connections dedicated to it on the wiring harness.
- Unbolt and unplug the original regulator and rectifier from the tray to remove them from the motorcycle.
- Unplug and remove the flasher relay from the electronics tray.
- Unplug the remaining connections that connect the electronics tray to the main wiring harness. This is the 2 on the left side (the stator and starter motor/flasher connector), the fusebox connector, and the starter solenoid, the one way diode, and the stater motor safety unit (if your motorcycle uses it).
- Unbolt the 2 mounting bolts that hold the electronics tray to the motorcycle and remove it.
Modifying the Electronics Tray
- Locate the factory rectifier mounting tab and mounting stud at the bottom of the tray. Unbolt the nut on the top of the stud and remove it from the mounting tab. With the stud removed, the tab should look like the photo below:
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With the stud removed, use a bench vise our adjustable wrench to grab the mounting tab and bend it down so that its flat and inline with the electronics plate. See photo below:
- Reinstall the stud so that it points straight out as shown in the previous photo. The larger half moon side of the stud should face the tray with the m6 side of the stud facing out to mount the new regulator/rectifier on.
- The second modification is to file the top right corner of the original rectifier wiring harness hole until it aligns with the other hole on the regulator rectifier. The regulator/rectifier should face with the wires extending through to where the original regulator was mounted. Add a small amount of paint to cover the exposed metal from filing and prevent rust. See photos below for mounting orientation and hole filing example:
Filed hole alignment with regulator / rectifier combo unit
Filing the White Plastic Harness Connector
Due to the closeness of the upper mounting bolt for the new regulator/rectifier combo unit, we found that we needed to file a small amount stator wiring harness plug flange to make clearance for the large diameter washers we used for mounting. It's possible that your electronics tray has more clearance depending on the model CB550 or there is room with a smaller washer. We recommend filing the plug to use a large washer to ensure a solid connection to the filed hole of the electronics tray when possible.
Stator harness plug - filed for clearance
Upper regulator/rectifier mounting hole - shown with large diameter washers used for mounting
Mounting the New Regulator Rectifier Combo Unit
With clearance made and the electronics tray modified, the regulator/rectifier unit can be mounted.
- Use 2 m6 washers as a spacer on the lower mounting studs that the unit can sit flat when mounted on the electronics tray.
- Use an m6 bolt with a large washer to go through the rear of the electronics tray, through the filed hole, and into the upper mounting hole of the new regulator/rectifier. We reused the bolt and large washers used to mount the original regulator. Use an m6 nut, lock washers, and washers on the top of the regulator/rectifier to secure everything in place.
Routing the Wires
- The wires of the new regulator/rectifier unit plug directing into the original rectifier and regulator harness connections without need for any modifications. In our installation, we ran the wire to where the original rectifier was mounted and plugged with into the the proper wiring harness connections. The wires were then coiled and zipped neatly in place.
- Be sure that the wires are neatly tucked against the rear of the electronics tray as there is almost no roomer between the tray and airbox assembly.
- With the new regulator/rectifier now occupying the original flasher relay location, we recommend zip tying the flasher relay mount to the edge of the one way diode mount so that it sits in the void that used to house the original regulator unit along with the other wire connections.
- With everything mounted, reinstall the electronics tray into the CB550K, CB500K, and CB550F. Plug in the connectors, reconnect the starter solenoid, and reconnect anything else that was removed during this process.
The installation is now complete!