Regulator Rectifier for Honda CB350F, CB400F, CB500, CB550F & CB750 Four 1971-1978
Regulator Rectifier for Honda CB350F, CB400F, CB500, CB550F & CB750 Four 1971-1978
SKU:RMS020-103102
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Regulator Rectifier for Honda CB350F, CB400F, CB500, CB550 & CB750
Honda CB Four models 1971-1978 - Part number RMS020-103102
This is a brand new aftermarket voltage regulator rectifier for the Honda CB350F, CB400F, CB500, CB550F Super Sport, CB550K, CB750K and CB750 Four built between 1971 and 1978. It is a direct replacement for your original unit: plug-and-play, direct fit, easy installation, with no assembly required. On these machines the job that was originally split between a mechanical regulator and a separate rectifier is handled here in one modern solid state unit, converting the alternating current from the alternator into direct current and holding the charging voltage steady.
A higher grade of electric components is used throughout, so the quality surpasses the OEM equipment, and every product is tested before it is shipped. The opposite connector for the main harness side is included in the package, because the original connectors on bikes of this age are very often melted or corroded and are a frequent cause of repeat charging faults. The unit carries seven wires on a single seven pin plug: three yellow wires go to the stator, red to battery positive, green to the frame and battery negative, black to ignition switched +12 V, and white to the field coil.
Key Features
- Direct replacement for the original unit - plug-and-play, no modification required
- Solid state design built with a higher grade of electric components than the OEM part
- Seven wires on a single seven pin plug, including the white field coil wire these models use
- Regulates to 14.5 V +/- 0.5 V and handles up to 50 A / 500 W
- Open circuit voltage held below 15 V
- Rated for operation from -20°C up to 85°C
- Matching main harness side connector supplied in the box
- Every unit is tested before shipping
Technical Specs
| Specification | Detail |
|---|---|
| Width | 72 mm |
| Length | 81 mm |
| Height | 29 mm |
| Wire length | 215 mm |
| Fixation holes, centre to centre | 61 mm |
| Number of plugs | 1 |
| Number of pins | 7 |
| Number of wires | 7 |
| Minimum charging voltage | 14.5 V +/- 0.5 V |
| Maximum charging current | 50 A / 500 W |
| Open circuit voltage | Less than 15 V |
| Operation temperature | -20°C to 85°C |
| Wiring | Yellow x3 to stator, red to battery positive, green to frame and battery negative, black to ignition switched +12 V, white to field coil |
Vehicle Fitment Guide
Years shown are the overall coverage span for this part. Please confirm against the OEM part number on your original unit before ordering.
| Make & Model | Years |
|---|---|
| Honda CB350F | 1971-1978 |
| Honda CB400F | 1971-1978 |
| Honda CB500 | 1971-1978 |
| Honda CB550F Super Sport | 1971-1978 |
| Honda CB550K | 1971-1978 |
| Honda CB750K | 1971-1978 |
| Honda CB750 Four | 1971-1978 |
OEM Part Number Cross Reference
Aftermarket replacement. OEM part numbers are listed for reference only.
| Part Number | Manufacturer / Brand |
|---|---|
| 31700-323-015 | Honda |
| 31700-333-008 | Honda |
| 31700-341-015 | Honda |
| 31700-300-035 | Honda |
Frequently Asked Questions
Will this fit without modification?
Yes. It is a direct replacement for the original unit on the listed Honda CB models, using the same single seven pin plug and seven wires, so it is plug-and-play with no assembly and no modification required.
What is included?
The regulator rectifier unit itself, plus the opposite connector for the main harness side. That extra connector is supplied because the original one on these bikes is so commonly melted or corroded.
How can I tell the old unit has failed?
With the engine running the battery should read around 14.5 V +/- 0.5 V. If the voltage never rises above resting battery voltage nothing is being put back into the battery, and if it climbs well beyond 15 V the regulation has failed. A battery that repeatedly goes flat or repeatedly boils dry, and bulbs that keep blowing, are the usual symptoms.
Which wire goes where?
The three yellow wires connect to the stator, red goes to battery positive, green to the frame and battery negative, black to ignition switched +12 V, and white to the field coil. Always compare against your own loom before making the final connections.
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