Topic: CB550 Overcharging. Is this a fix?

[Itineo]

Just thinking out loud. My CB550f has been overcharging and I’ve followed the diagnostic procedure posted here, I understand how the system works and I’m fairly sure of the cause  - there’s a 2V voltage drop between battery positive and VREG input. So the VREG thinks the battery voltage is lower than it actually is and is overcompensating. (1979 Uk spec bike all factory standard) I’m getting around 16v at 3,500 rev/min. Bike has been fitted with an aftermarket Reg/rec with white/black joined together in the usual way for these. I expect the voltage drop is going to be due to something likely in the ignition switch as I’ve replaced the loom, fuse box etc. If I run a wire from the battery positive to the white/black connection on the reg/rec the charging voltage drops right away to what it should be - 14.5V, which points to a problem/bad connection in the circuit between battery/ignition switch/VREG.  So what if I were to put a solid state relay between battery positive / VREG, switched by the ignition?  I probably won’t take this shortcut and will trace the cause and fix it as I like to keep things original and cure the cause rather than the symptom.
Just a thought.

Second question - has anyone ultrasonically cleaned the electrical contacts in an ignition switch. I think the problem is going to be inside the switch unit as everything else is new and clean. I’ll know once I put a meter on it over the weekend. Any thoughts/advice beside renewing it?  It’s tempting to try to clean it like a PCB. 

[Deltarider]

The usual suspects are the fuse and its clamps and the keyswitch. They're easy to check by measuring the V-drop over them. If you're not familiar with locating a V drop in a circuit, below two pictures that demonstrate  a complete V4 measurement. Realise that each pic shows two measurements.

[Deltarider]

Why did you replace the stock regulator and rectifier? They're both known robust and reliable. I hope you haven't fallen to this 'deficient charging' myth. It only exists in this forum.

[Itineo]

Why did you replace the stock regulator and rectifier? They're both known robust and reliable. I hope you haven't fallen to this 'deficient charging' myth. It only exists in this forum.

Early days and I gave the bike to a local garage to reinstate from a long period of being idle. He replaced the unit with the combined Reg/rec. As a fait accompli. The originals are still in place and to be fair the thought had crossed my mind. Since then I’ve educated myself on how the charging system works and you make a fair point. But the new unit does what it should if I feed it the correct voltage so at this stage if it ain’t broke… ( yes I know ```)

Thanks Deltarider in response to your first answer - Yes that’s what I have in mind. I got a new fuse box to eliminate a problem I was actually able to measure between the clip and the connector block.  So the only remaining culprit has to be the keyswitch, I’ve replaced the main and sub wiring harness, all earths are good so there’s nothing left. It’s conceptually straightforward to do and I’m sure It’ll work out.  I’m thinking giving the switch unit a minute or two in the ultrasonic using Petrol (Gas) as a solvent to avoid any further corrosion. Haven’t stripped it or looked at in detail so maybe this is a bad idea or there’s an easier way to do it?? 

[Itineo]

I think the idea of replacing a ‘known defective’ Honda Reg/Rec is possibly a bit of wishful thinking that it’s the only source of the problem. It would be lovely to swap one component out and live happily ever after.  My overcharging issues were due to corroded wiring, poor connections and remain so. I’ve found a temporary fix that is independent of the hardware, that I suggested in my first post.  So possibly there’s nothing wrong with the original units. I’m not sure if I’m masochistic enough to rewire them once I fix the problem to test that hypothesis. I wonder if a lot of people who don’t use their old bikes as daily riders don’t spot these problems as the batteries expire from neglect rather than overcharging?  Guilty as charged (pardon the pun) myself as i’ve killed a fair few batteries on old bikes of all sizes over the years due to neglect.  Here in Ireland most of the bikes from that era died from the damp climate. I’m very happy to be keeping a few alive.

[bryanj]

Nothing wrong with the relay idea, if the ignition switch is between the clocks they are pricey, if available, from Honda pattern ones can be got but quality can be suspect. Ultrasonic clean is suspect but normally the contact part can be carefully taken apart and cleaned.
Have you joined the UK forum?

[Itineo]

Thanks - Didn't know there was one. I’m in Ireland so much the same thing as regards bikers. Where’s it at?

[robvangulik]

http://www.sohc.co.uk

[Itineo]

Thanks. Registered there now

[bryanj]

See you soon then, Steve will authorise it soon