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SOHC.co.uk Forums => CB500/550 => Topic started by: Mike_Berkshire on November 20, 2024, 07:40:13 AM

Title: Maintaining a good earth connection
Post by: Mike_Berkshire on November 20, 2024, 07:40:13 AM
I have learned the importance of a good earth on my bike after having replaced burnt out green wires in both main and sub harnesses. There is no paint now on my rear top right engine bracket and I am going to ensure paint is removed from the coil mounting earth point and where the engine bracket touches the frame. Should I protect these earth points from corrosion using a little grease or something once the connection has been made?
Title: Re: Maintaining a good earth connection
Post by: McCabe-Thiele (Ted) on November 20, 2024, 08:18:10 AM
That's an interesting question Mike,  in the olden days that I remember you cleaned up a battery terminal then added grease to the outside of terminals afterwards to keep the moisture out.

Greasing the contact point itself wiould make a poorer contact unless the grease used was conductive, it will be interesting to read the contributions on this subject.
Title: Re: Maintaining a good earth connection
Post by: Sesman on November 20, 2024, 09:06:27 AM
Interestingly I didn’t remove any powder coat in those areas and still have an excellent earth. If the earth connection point is a bolt through(eg a fixed thread in the frame or a welded nut) then I’m unclear why removing paint is necessary?. I’ve tested my connections for conductivity and all appears to be fine.

I cover all exposed connections with Vaseline (petroleum jelly). I also press Vaseline into all the crooks and crannies in the mudguards (the 500/550 rear mudguard is a prime candidate) to prevent ingress of moisture.
Title: Re: Maintaining a good earth connection
Post by: SteveW on November 20, 2024, 09:18:51 AM
Tell tale signs of a bad main battery earth to the frame. The current uses the small green earth wire instead.
Title: Re: Maintaining a good earth connection
Post by: ST1100 on November 20, 2024, 09:38:06 AM
Should I protect these earth points from corrosion using a little grease or something once the connection has been made?
I've made good experience with a squirt/whiff ACF-50 on such grounding points...
Title: Re: Maintaining a good earth connection
Post by: Sesman on November 20, 2024, 10:32:06 AM
Tell tale signs of a bad main battery earth to the frame. The current uses the small green earth wire instead.
.

I checked my battery negative connection prior to connecting the ignition earth. Both connections need to be checked for continuity/conductivity independently to avoid the issue you have experienced.
Title: Re: Maintaining a good earth connection
Post by: Mike_Berkshire on November 20, 2024, 10:21:51 PM
Thanks for the thoughts hunts and tips team!
Title: Re: Maintaining a good earth connection
Post by: Mike_Berkshire on November 22, 2024, 05:11:20 PM
I have made sure all the mating surfaces are paint-free and fitted a new earth strap to the battery/engine mount plate. Measuring resistance between the battery earth terminal and various points on the bike such as the engine block, rocker cover etc I get a reading of 0.2 Ohms. That seems OK?
Title: Re: Maintaining a good earth connection
Post by: McCabe-Thiele (Ted) on November 22, 2024, 06:10:29 PM
My 500 had an extra earth cable fitted similar gauge cable to the battery earth connector fitted  by a PO (not Bryan as I asked).
I failed to take a photo of where it was fitted on strip down,  thinking that's a good idea I'll fit that back there on assembly. The cable is in my spares box, for if & when I remember where it goes.

0.2 Ohms - I have no idea if that's good or bad, I went for plain voltage drop (well lack of) in my ignorance.
Title: Re: Maintaining a good earth connection
Post by: Bryanj on November 22, 2024, 06:48:45 PM
Thats probably zero unless you have a meter where you can set the zero and is pretty good
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