Not suire if Reg/Rect.is grounded properly

[gs11ezrydr]

I'm putting back together a 86 GS1150 and noticed there was a ground wire ran to the - post. Someone has bypassed the 5 pin plug but only with the ground.... Coming out of the harness. I'll start the bike tomorrow hopefully.I think the reg is grounded directly to the battery..,"good or bad" and all the lights work so the chassis must be grounded... But I was needing advice in how to insure the Reg/Rect. is grounded before smoke rolls..Stator olmed out fine..Thanks..

[Brendan W]

To my way of thinking, the R/R is grounded correctly when it is connected directly to the returning current flows. If the lights etc are grounded to the frame and the R/R to the frame you have the probability that the R/R ground is not at the same potential or voltage and will have the wrong idea about what is happening. It is what runs the bike like a small power plant. Many of us have collected the returning ground wires to a single point ground, SPG, post and made that the R/R ground. The frame and it's connections in and out are no longer in the loop.
Why is this an issue? Amongst other things, if the R/R does not know the true state of the system, being lied to by voltage losses at frame connections, then it will probably be undercharging the battery. It can also lead to currents going in pointless loops.
In this view the battery is a thing apart. It sits in parallel with the bike load and it's negative terminal is also connected to the SPG.
You will hear it said that you can't have too many ground wires. I'm not sure that is true.
Any chance of a picture?

[gs11ezrydr]

Thanks..Very good advice..And yes I have been reading up on SPG...Makes sense to me..

[Who Dat?]

Although the concept of SPG is good, why can the frame not be considered as an SPG? As long as all connections are good, the whole frame should be able to be considered as a "single point". Or am I missing something?

[Brendan W]

Although the concept of SPG is good, why can the frame not be considered as an SPG? As long as all connections are good, the whole frame should be able to be considered as a "single point". Or am I missing something?

That's a valid enough argument as long as the connections are good. Even if they aren't perfect how much difference can it make?
For me the returns were above the airbox and out of sight with all that entails. Now they are on the starter solenoid post as is the R/R ground and a wire to the battery negative. This has the added bonus of providing the solenoid with a good clean earth. At the back of my mind as well is the notion that the charging system is marginal and anything I can do to make it even a little bit better is worthwhile even if I can't measure it.

[Rijko]

Although the concept of SPG is good, why can the frame not be considered as an SPG? As long as all connections are good, the whole frame should be able to be considered as a "single point". Or am I missing something?

The way these bikes were built was good enough to make it last almost 40 years.
And there is no reason it will not function properly for decades more that way.
Nothing wrong with using the frame as ground, SPG or however you want to call it.

The thing is - old wiring and old connections tend to corrode.
I have a dozen or so 1979 GS1000 bikes running well without SPG or upgraded R/R or other modifications.
But i am meticulous in cleaning and repairing the wiring loom, connectors, handlebar switches, etc etc.
Measuring resistance for every wire and ground connection.
I find not many people are prepared to spend weeks on that.