Author Topic: 400 four earth points  (Read 5083 times)

Offline exvalvesetdabbler

  • SOHC Pro
  • Posts: 587
    • View Profile
Re: 400 four earth points
« Reply #15 on: August 05, 2026, 06:51:36 PM »
The one that's working came off a bike  with 72k recorded mileage, so we'll see how long it lasts.
The black cover was a bit crusty so might be original. Inside looks good as new.

Dave.

Offline Mikep328

  • SOHC Pro
  • Posts: 535
    • View Profile
Re: 400 four earth points
« Reply #16 on: August 05, 2026, 06:59:07 PM »
Just curious - did you think about replacing the OEM rectifier and regulator with a solid-state "modern" component like the one DSS sells? 
Mine:
1976 CB400F
1973 Norton 850 Commando
2015 BMW R9T
2017 BMW R1200RS
2021 Moto Guzzi V7 Special
Wife's:
2015 Ducati Diavel
2019 Honda Africa Twin
2019 Honda NCT750

Offline Bryanj

  • Grogu
  • *
  • Posts: 12561
    • View Profile
Re: 400 four earth points
« Reply #17 on: August 05, 2026, 08:40:30 PM »
Best thing for cleaning point, wherever fitted, is a thin flat diamond file, i have lost my 45 year old one!!

Offline McCabe-Thiele (Ted)

  • Grogu
  • *
  • Posts: 8622
    • View Profile
Re: 400 four earth points
« Reply #18 on: August 05, 2026, 08:43:51 PM »
Best thing for cleaning point, wherever fitted, is a thin flat diamond file, i have lost my 45 year old one!!

Wendy would not lend me her diamond dust nail file. ☹️
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline exvalvesetdabbler

  • SOHC Pro
  • Posts: 587
    • View Profile
Re: 400 four earth points
« Reply #19 on: August 05, 2026, 08:54:21 PM »
Just curious - did you think about replacing the OEM rectifier and regulator with a solid-state "modern" component like the one DSS sells?

The standard set up is normally reliable, well it lasted 49 years.  The only advantage would be if the maximum output was more in line with battery manufacturers guidelines for sla or AGM batteries.

Regards
Dave

Offline McCabe-Thiele (Ted)

  • Grogu
  • *
  • Posts: 8622
    • View Profile
Re: 400 four earth points
« Reply #20 on: August 05, 2026, 09:18:36 PM »
Just curious - did you think about replacing the OEM rectifier and regulator with a solid-state "modern" component like the one DSS sells?

I considered that option, not sure how comprehensive the wiring guide is that presumably comes with the kit.
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline Oddjob

  • SOHC Jedi
  • Posts: 4735
    • View Profile
Re: 400 four earth points
« Reply #21 on: August 05, 2026, 09:49:56 PM »
Just curious - did you think about replacing the OEM rectifier and regulator with a solid-state "modern" component like the one DSS sells?

If you're thinking of this make sure it's one that uses Mosfets, I think the Electrex one does but ask first before buying.

https://www.electrexworld.co.uk/cgi-bin/sh000001.pl?WD=cb550f&PN=RR24%2Ehtml#SID=439
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Mikep328

  • SOHC Pro
  • Posts: 535
    • View Profile
Re: 400 four earth points
« Reply #22 on: August 06, 2026, 05:48:18 AM »
That's the same unit DSS sells - though both Electrex and DSS are out of stock on them at the moment.

I had thought about replacing my rectifier/regulator with one of these back when I first bought my 400F several years ago but since the OEM units were working fine (and still are) I decided to wait until they quit!  :)
Mine:
1976 CB400F
1973 Norton 850 Commando
2015 BMW R9T
2017 BMW R1200RS
2021 Moto Guzzi V7 Special
Wife's:
2015 Ducati Diavel
2019 Honda Africa Twin
2019 Honda NCT750

Offline TrickyMicky

  • SOHC Pro
  • Posts: 558
    • View Profile
Re: 400 four earth points
« Reply #23 on: August 06, 2026, 06:27:40 AM »
I fitted one of the new DSS  combined units 10 years ago after a charging fault, just about limped home, thank Gawd for the kickstart!!  I am not an electrician, especially when it comes to charging/rectifier systems. After making a mounting plate from an old brass window hinge, (yes, really!), the new 'potted' unit was fitted where the old regulator was sited under the left side=cover. There was just enough slack in the wiring to the old rectifier to reach across to the left side. So far, so good.

Offline exvalvesetdabbler

  • SOHC Pro
  • Posts: 587
    • View Profile
Re: 400 four earth points
« Reply #24 on: August 06, 2026, 05:27:11 PM »
Here's what I found after trying to clean up the contacts.

[ Guests cannot view attachments ]
[ Guests cannot view attachments ]

Not sure if this can be saved

The bottom contact cleaned up ok

Regards
Dave

Offline Bryanj

  • Grogu
  • *
  • Posts: 12561
    • View Profile
Re: 400 four earth points
« Reply #25 on: August 06, 2026, 11:49:45 PM »
Need a clean with a diamond file

Offline exvalvesetdabbler

  • SOHC Pro
  • Posts: 587
    • View Profile
Re: 400 four earth points
« Reply #26 on: August 16, 2026, 03:57:29 PM »
I have tried making adjustments to the failed regulator after having cleaned the contacts. Charging with the headlight on is happening right down to 2500 rpm, below that the battery is just about breaking even. This is done by bending a tab that preloads the strip of spring steel on the armature as per the shop manual.

With both the replacement and the refurbed regulator I'm still seeing 15.6v without the headlight on if I ride it like I stole it so a little fine adjustment for mode3 is needed.  Where that happens turning the headlight on drops it to 14.4-14.6 so I can manage that for now. Probably no bad thing having the headlight on when tearing around like a scolded cat.

Setting mode 1-2 transition on a bench power supply with a lamp in place of the field coil is straight forward.

Setting mode 2-3 transition is a little more tricky.  With the power supply current limited just below the current drawn when it's hard into mode 3, provides some simulation of the interaction between field coil excitation and voltage that gets the  contacts vibrating but the observed transition is about 0.6v lower that what it produces in the bike.

Armed with that data I'm fairly sure I can reduce the max voltage to acceptable limits. I haven't played with this adjustment yet.

As a parallel issue I have been looking at how these combined units work without the benefit of a big ballast resistor to switch in/out as needed.  It seems a good proportion of these devices achieve regulation by pulsing a short circuit across the stator.  Obviously MOSFET transistors are better in this scenario than bipolar transistors because of the lower on resistance and negligible heating, it  does mean that your alternator is running at max output regardless of how much power is used and how much  is dumped at source.

Does any one have any solid info on any combined units that actually modulate the supply to the field coil the same as the OEM reg.

All of the sales patter I have read doesn't really go into operation of the device.

Regards
Dave

Offline Oddjob

  • SOHC Jedi
  • Posts: 4735
    • View Profile
Re: 400 four earth points
« Reply #27 on: August 16, 2026, 04:07:07 PM »
Try an email to Electrex. They seem to be ok on answering questions.

15.6v seems excessive. Battery boiling time  :) :)
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline exvalvesetdabbler

  • SOHC Pro
  • Posts: 587
    • View Profile
Re: 400 four earth points
« Reply #28 on: August 16, 2026, 04:47:27 PM »
Yes and even worse if I want to keep it down further for AGM.

It probably won't boil at that but will need frequent deionised water top ups

Thing is without real time voltage readings you probably wouldn't know as I didn't coming home after dark and seeing the battery voltage creeping down below 12.5.

For now I'm getting solid 13.5 -14.5 over a range of conditions which is better than what I had before, draining the battery with the headlight on.

I didn't see this coming since I was getting 15 going down the open road without headlight but looking at the voltages, it probably wasn't putting much back into the battery pottering around town. Goes a long way to explain why a 3 year old  battery is struggling to turn the engine over. I kept it on an optimate over winter but didn't bother much over summer where it was used regularly.

Regards
Dave

Regards
Dave.

Offline Oddjob

  • SOHC Jedi
  • Posts: 4735
    • View Profile
Re: 400 four earth points
« Reply #29 on: August 16, 2026, 04:59:03 PM »
I managed to install a digital volt meter inside my tacho. I was also concerned about battery drainage and over volting etc and wanted to keep an eye on it without having a eyesore of a gauge or meter stuck somewhere. Saw something on Alan Millyards 6 cylinder Z1 and thought it was a great idea, as I had the tacho apart for renovation I thought I’d try and fit it in there instead. Waterproof and highly visible. Had a choice of colours as well, still undecided on which one I’ll go for, blue is too bright, red is right in your face, green looked ok as did amber. Might put a small resistor in the lighting wire to see if I can mute the brightness a little.

I posted a pic of it a couple of years ago and go slated for doing it by those who think it’s not needed. I ignore them, it’s my bike I’ll do what I want. If I end up not liking it I’ve got a spare tacho already renovated to fit in its place. 550f2 clock btw. Not sure there enough space inside a 400 or 500 clock.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.