Acceptable voltage loss

Windmill John

Windmill John

Veteran Member
Joined
Jun 4, 2022
Total Posts
811
Total likes
369
Location
East Sussex, England
I could have tagged this onto my headlight thread, but not the same issue and I thought the title made sense. I did search for similar.
Whilst I will look at a battery later, for the minute, it has enough at 12.33…
  • Okay, I’ve cleaned many earthing points.
  • Stripped and cleaned starter button
  • Stripped and cleaned head light switch
  • Stripped and cleaned ignition switch (Note, 12.3 going in, only 12 coming out.) crazypj mentioned less than 11 bad, so I should be happy.
  • I couldn’t work out, without damage how to remove the kill switch knob, but removed assembly and thoroughly sprayed with brake cleaner whilst operating switch. Could this be an area of voltage loss? A question for later.
Voltages
12.33 at battery
12.32 at wire into ignition switch
12 at black wire out.
Headlight 11.8 low beam
Headlight 11.7 high beam
Brown wire at rear light cluster, 11.1 Note, my cleaning has got this up from 10.5 volts
Oh, and pleased with over 10 volts at battery when cranking.

Okay, I am happy with this considering age of bike. But, would you be? This will certainly run the bike when I do eventually start it for the first time.
I want a big fat “Yes, get on with it” 😉😊
 
With a discharged battery it’s not a really valid test with static loads.

It does point to insufficient paths to ground and corroded wiring in the harness.
 
I would agree with Pete that the battery isn't up to snuff and should be in the 12.75 range, so your starting with a low battery IMO. The other issue is as Pete noted these wiring harnesses suffer from copper degradation over the 50+ years. I have stripped back many a wire to find black copper inside which is a resistance point throughout the harness.
I have always replaced every wiring harness on any build I have done now for years, as a guarantee of not having that issue. I may not be an option for you presently. You would possibly have to search for Thailand vendors for a replacement aftermarket harness.
Best to keep TESTING your circuits as your going through the bike once you have it running. Then see where your at voltage wise with a running bike and if the headlight and taillight and signals work correctly.
 
Thanks both. All lights are good. As mentioned, once the bike is running, then my first stop will be a new battery.
Red contact in the ignition switch did need a good scrub and yes, I expect some wiring, although looking good, will have deteriorated under the insulation.
I haven’t done a full strip, more of a bring back to ride. I’ll feel much better when I take it out for a ride. Never ridden a Hondamatic!

I’ll close off, taking note of your comments and see these as jobs as I go along.

Cheers guys.
 
Well, due to the extreme pressure applied by the guys here to buy a new battery 😉 I rode over to Wemoto this morning to pick one up. A 60 odd mile round trip, I left around 9:00 due to only being a million degrees then. Given up worrying now about temp and just bath in the evening…. To be wet straight afterwards 🙄 Looking forward to popping the battery on and checking voltages. As it’s 45 degrees in the shed, I might wait a mo 🙄
 
Richard Pitman said:
How are you coping with this heat ? Too hot to ride here, unless one does a Rollie Free.

36 centigrade and humid, 3rd day of this. 🥵
Click to expand...
Today 37, tomorrow 40, and still on the CB400F. The engine stalled yesterday afternoon, coming from the highway (doing 140 km/hour for 5 minutes), after standing still for a traffic light. Vapour lock, or boiling petrol. After a few minutes, I could start the engine again. As long as you move, no problem with the heat, but as soon you stand still in my black motorcycle jacket and trouser........
 
jensen said:
but as soon you stand still in my black motorcycle jacket and trouser........
Click to expand...
I guess that’s one of the ‘advantages’… of being a teenager, wearing just a T shirt. I remember someone… ahem… wearing just a pair of shorts at 17 riding my, sorry their 😊 DT100. Now, I, sorry, they.. wear protective gear etc.
 
Right, just fitted new battery; fully charged.
I had a moment of satisfaction at 11.49 volts at rear light cluster. This over the next few seconds dropped to 10.9 volts.
I'm going to leave it for the mo. Surely the headlight being on will affect this and the fact on a circuit should drop to zero volts At completion?
 
You must log in or register to reply here.
Back
Top Bottom