Regulator Rectifier for Honda CB400 and CM Series Motorcycles
New aftermarket replacement part
Regulator Rectifier for Honda CB400 and CM Series Motorcycles - a new aftermarket regulator / rectifier, supplied ready to fit.
The regulator/rectifier converts AC from the stator into regulated DC. When it fails you get boiling batteries and blown bulbs from overcharging, or a flat battery from no charge at all.
Key Features
100% new aftermarket unit - not a remanufactured core
Direct-fit replacement, no modification required on listed applications
Built to meet or exceed the original equipment specification
Dispatched from the UK with technical fitment support
Technical Specs
Specification
Detail
SKU / Part Code
RM30003
Component
Regulator / Rectifier
Condition
New aftermarket
Warranty
12 months
Vehicle Fitment Guide
Model
Years
Compatibility: Honda CB400, CB450, CM400, CM450
1978-2016
Honda CMX 250 Rebel
1985-2016
Honda GB 500
1989-1990
Honda CH 150 Elite
1987
Honda CB 450 Nighthawk
1982-1986
Honda CM 450 E and Hondamatic
1982-1983
Honda FT 500 Ascot
1982-1983
Honda CB 450 Hawk
1982
Honda CM 450 Custom
1982
Honda CM 200 T
1981-1982
Honda CB 400 Hawk
1978-1981
Honda CM 400 Hondamatic, Twin, E, Custom
1979-1981
Honda CB 400 Hawk II
1978-1979
Honda CB 400 Hondamatic
1978
Frequently Asked Questions
How do I test a regulator rectifier?
Measure battery voltage with the engine running: below about 13.5V means undercharging, above about 15V means the regulator has failed open and is overcharging. Check the stator output first so you do not replace the wrong part.
Does it come with the connector?
It is supplied with the original style connector on the models listed. Check the images against your existing unit.
Why do these fail so often?
Heat. They dissipate excess charging current as heat, so a blocked cooling fin area, a corroded earth or a weak battery all shorten their life. Mount it where it gets airflow.
Will a failed regulator damage anything else?
Yes - overcharging cooks batteries and blows bulbs, and a shorted regulator can take the stator with it. Fit the replacement promptly.
Dispatched from the UK · 12-month warranty · Fitment support from our technical team
