Author Topic: Does this electrical mod apply to the CB400 four?  (Read 404 times)


Offline AshimotoK0

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Re: Does this electrical mod apply to the CB400 four?
« Reply #1 on: September 11, 2023, 07:05:37 AM »
Most definitely not ! Only for single phase Honda's with day/night charging stator coil type alternators.

I don't think that article is strictly correct anyway because when the bikes were new, the daytime coil was perfectly capable of supplying the charge but 50-> 60 years later the permanent magnets in the rotor have lost a fair amount of magnetism. The single phase system uses 'current-dumping' of excess charge into the shunt type regulator fitted to the later Honda twins. For bikes without the regulator (i.e Black Bomber CB450K0 and CB72/77) if you connected the night time charge coil permanently, you would have fried the battery. But for a 50+ year stator the reduced magnetism means you would need to connect the night time coil to maintain a constant positive charge into the battery, mindful that if it's a model without a regulator then best to fit one from a later model (i.e CB250/350K twin) or there may well be an aftermarket rectifier/regulator for the twin bikes.

On your 400F,  the 3-phase system modulates the current into the battery in a more sophisticated way (i.e it adjusts the current in the field coil via the regulator to meet the electrical demand of the bike and has no permanent magnets in it) . This has been discussed in details many times on here.
« Last Edit: September 11, 2023, 07:21:18 AM by AshimotoK0 »
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