rotor

[kevski]

Just out of interest, does anyone know if permanent magnet rotors are made for our bikes, 350/400.

[Bryanj]

If you mean the 4 cyl then no and they are not permanent magnet the rotor is simply a lump of normal steel with a wavy groove, it is the inner coil that produces the magnetism and the groove makes it fluctuate across the outer coil generating electrikery

[kevski]

The question is does anyone make a permanent magnet rotor, i already know they have a excited coil magnet rotor.

[Bryanj]

never heard of one, it would be difficult to regulate the output

[kevski]

A PMA would be a much needed modification to these bikes, my big Z has one, i put one on my XS650, i only asked as my 350f charging system has gone down, new R/R and sowing 16+v at 4krevs and 11v on idle with lights on, 4 things to go wrong and analyse, PMA only 2.

[Bryanj]

You can clean and adjust the regulator contacts

[kevski]

Already cleaned and adjusted the regulator contacts to no avail, will go with a combined unit, it's out of sight so will not spoil view.

[Bryanj]

Personaly I don't like the combined electronic as they seem far too fragile and used good regulators are out there all the fours are the same

[Trigger]

I had the same problem a month ago, did not notice it was pushing out too much and cooked the battery. Found a good secondhand one that works fine.

[kevski]

The problem is finding good second hand units, as these are pushing 50 years old it is getting harder, so an update to something modern and reliable only makes sense, it will be the same when the points/condensers need replacing, i will upgrade to electronic ignition, the next owner can have all the original parts if and when i sell the bike.

[AshimotoK0]

I agree with you Kev ....  rare earth magnets now make the permanent magnet rotor much more attractive (I recently rewound a Harley rare-earth P.M. aftermarket alternator and pulled 1.2kW from it,  as I upped the output voltage to around 200v  albeit for a non bike work project). Back in the day I had two 400/4 stator's go bad on me...both the same fault..... corrosion causing breakdown of the magnet wire lacquer insulation and hence a short circuit to the laminated mag-frame. The bikes were less than 10 years old when they failed. They run dry (like the 500/4) and I have never seen that fault with other Hondas that run in the engine oil.

The 3-phase system on the Honda fours is a brilliant system though IMHO because the system only powers the field coil  and induces magnetism into the rotor, on demand, as required. With a PM system, you have the constant magnet drag, which means you have to dump the excess power generated  with a 'crowbar type circuit ...or like on the Triumph twins from the late 60's onward rather crudely with a Zener diode.

I notice that DS now does an aftermarket CB400/350 four stator: On first glance it looks pretty well constructed.

 https://www.davidsilverspares.co.uk/CB400F0-SUPER-SPORT-1975-USA/part_322118/