Grounding question

[willis]

ok, so today I started re-wiring my bike. Its a '78 special and I'm decluttering and eliminating the un-necessary items. I am retaining the stock hand controls along with turn signals and e-start. I've spent a lot of time researching a creating a nice diagram to follow up to this point but have probably confused myself by going cross eyed looking at all the wires. I am just looking for some reassurance if I'm thinking right or if I'm over thinking this.

So I was previously under the impression that I needed to run a ground wire from the starter button, but have come to the realization that it is self grounding to the bars. Do I still need to run the ground wire from the left side control to complete the ground loop? I've read up and think I should tie the ground from the headlight cluster coming out of the left controls into my main ground. I'm using nice bullet connectors from Vintage Connection and have a main ground line running front to back with splices feeding into it and will continue it up into the headlight bucket. I am grounding that to the battery in back as well as the top motor mount in front. Please tell me if I'm over thinking this or I'm on track.

 

[fredintoon]

Hi willis, sure the starter button grounds to the bars but be certain sure the bars are grounded back to the battery, eh?
There should be a ground wire because the ground route from bars via the bar clamps and through the headrace bearings ain't a sure thing.

 

[angus67]

Not only intermittent, but destroys the head bearings over time

 

[TwoManyXS1Bs]

Some bikes ran a ground lug from the threaded bottom of the handlebar risers...

 

[5twins]

Your ground set-up sounds correct, just like stock. Starter button grounds through the bars over to the left switch assembly. Left switch grounds into headlight via a black wire. All grounds in headlight run back to some main ground on the bike's frame.

 

[member3480]

I did a harness for a guy and he is having same problem and I told him the handle bars may not be grounded. Stock bike has a wire for trees but when you make up your own setup grounds are SO IMPORTANT and have one complete ground and not a bunch of little ones to frame will keep your parts working. The 12mm bolt on the back of motor and battery ground is the basic factory ground. I have done over 100 harnesses and more people run into a problem because they change the ground.

 

[gggGary]

Yes front end grounds varied through the years, early bikes had no fork to frame ground wire and Yamaha corrected THAT mistake in later years. But a handle bar to headlight bucket ground wire of some sort has always been used to bridge the rubber riser bushings, mid bikes, 75 era used a ground wire from the headlight bucket to the riser bolt under the top triple, later bikes used a ground wire in LH switch bundle from bucket to handle bar. On any of these; painted or powder coat handlebars can cause problems. These and the engine top mount grounds are often not shown in either factory or "custom" diagrams / charts leading to some serious hair pulling electrical gremlins for those doing rewiring "per the picture".

 

[willis]

Thanks everyone...

 

[willis]

After some minor adjustments, i am pretty happy with the diagram. It really starts to make a lot more sense when you break the wiring down into sections. Also helps when you spend a couple days checking and re-checking until you have gone cross-eyed. A copy of my latest draft is attached.

Oh ya... Thanks again Rich (Daddy G)for letting me pick your brain through this !!!

 

[Partsbike]

I have a slightly related question. When wiring a new build from scratch, are you guys doing up say a front and rear chassis ground or pulling a main ground wire front to back and tieing grounds into it along the way? I am planning out my hardtail wiring and debating on whether or not I'll weld a chassis ground down near the starter and another hidden under the tank or maybe just pull a designated ground wire from the rear up to the front. My plan then would be to tie everything (gauges, signals, headlight etc) directly to that wire. Any issue either way? Thanks!

-Ryan

 

[mrtwowheel]

willis, I sit here in envy of your diagram. I can wire a bike, but to have a specific diagram as nice as that for future reference, for you or anyone in the future to follow, is a great thing, good job.

Scott

 

[willis]

Thanks Scott. Electrical wiring has been my weakness as it is easy to become overwhelmed. I can't tell you how many diagrams i've made, then revised over and over in the last two weeks. It has really helped me understand the circuitry though. I am actually currently revising the one i posted here earlier as I am trying to be 100% accurate to where everything is positioned on the bike. Since I am still in the process of wiring it, I am sure it will continue to change. Once I am completely satisfied I will take it to work and have it laminated so I have a nice hard copy to reference and keep it with my manual. I actually am still contemplating purchasing a fuse block from Eastern Beaver. They are nice units and good alternative to the MotoGadget units, at a fraction of the cost. That would be just one more step in simplifying the harness and may upgrade it down the road.

http://www.easternbeaver.com/Main/Wiring_Kits/Fuseboxes/PC-8/pc-8.html

 

[XSLeo]

Partsbike, Yes a wire run from front to rear is good idea.
I would have one wire running off this main ground hooked to the battery, or cap ground. This insure the circuit is complete from the battery/cap back to the battery/cap. I might also have w wire tie into this main ground from a top engine mount bolt., this way you have a good ground for the ignition.
As DaddyG mentioned, grounds are very important. Things don't work without them.
Leo

 

[Partsbike]

Thanks for the reply, Leo. I'm starting from scratch and figured a continuous ground wire couldn't hurt. Just wasn't sure if it was necessary in my application. Thanks again.